1 Cell Theory SC.912.L.14.1. 2 Anton van Leeuwenhoek, who is considered to be the father of microscopy, began his work by learning to grind and polish lenses to increase their magnification.

It led to the discovery of cells and advanced our understanding of cellular processes. B.

It led to the discovery of genetic trait inheritance patterns. D.

It led to the discovery of cells and advanced our understanding of cellular processes.

stem cells B. existing cells C.

gametes B. existing cells.

cells B. DNA C.

ribosomes A. cells.

This phenomenon has been observed using electron microscopes and light microscopes. Which of the following best explains why cell theory is still considered a theory and not a law, even when there is observable evidence to support it.

Other aspects of cell theory do not have direct, observable evidence. B.

The theory has not yet gained wide enough acceptance to become known as a law. D.

Cell theory is a summary of a supported hypothesis, not a generalized observation.

It is passed from old cells to new cells during cell division. B.

It is passed between daughter cells and parent cells during meiosis. D.

It is passed from old cells to new cells during cell division.

All cells come from pre-existing cells. B.

The cell is the basic unit of life in an organism. D.

Each cell has a unique chemical composition.

Which of the following explains why viruses, themselves, are not considered living things. A.

Viruses do not have the capability to undergo sexual reproduction. C.

Viruses cause disease in living organisms, which can result in the death of that organism. C.

9 According to modern cell theory, the activity of an organism is dependent upon which of the following. A.

specialized cells that carry out metabolic processes C. the ability of cells to undergo both mitosis and meiosis D.

the total activities of independent cells. 10 The cell theory was first proposed in 1838.

Which statement describes a component of the original cell theory that was removed because of the new scientific knowledge. A.

All cells come from other preexisting cells. C.

Cells are the basic structural and functional units of life. C.

11 Which of the following is NOT a principle of the cell theory. a) Very few cells reproduce.

c) All living things are made of cells. d) All cells are produced by existing cells.

12 OUT OF 10 QUESTIONS 1/10 = 10% 2/10 = 20% 3/10 = 30% 4/10 = 40% 5/10 = 50% 5/10 = 50% 6/10 = 60% 6/10 = 60% 7/10 = 70% 7/10 = 70% 8/10 = 80% 9/10 = 90% 10/10 = 100%.

Cell theoryn., [sɛl ˈθɪɚ.i]Definition: Theory about cells to explain living things’ composition, function, and origin. Table of Contents.

It describes how we all start our lives with a cell that has been contributed by our parents’ existing cells. In its full integrity, a cell is an independently functioning and self-sustaining entity that arises from a pre-existing cell and gives rise to new cells in its lifetime.

This theory emphasizes the fact that all living beings (living organisms) are made up of a basic life unit called “cell” and each of the body’s cells has started its life journey from a pre-existing cell only. All cells have the same basic chemical composition.

The theory was later improved by Rudolf Virchow who explained that all cells have arisen from some pre-existing cells. Both speculated that cells originate due to spontaneous generation.

Watch this vid about cell theory: Biology definition: A cell theory is a scientific theory stating that:

The three principles of cell theory are discussed as the 3 parts of cells theory here. The cell theory states:

The cell theory beautifully explains how the human cell body is composed of trillions of cells, each with specific functions. Cells combine to form tissues (e.g., muscle tissue, nerve tissue), which then make up organs (e.g., heart, brain), which further constitute specific organ systems (e.g., circulatory system, nervous system).

Likewise, when we think about microorganisms like bacteria, archaea, protists, or fungi, don’t we all wonder how these microorganisms come to life. Even all of these microorganisms consist of one or more cells.

Are viruses too made up of cells.

The cell theory applies to single-celled organisms just as it does to multicellular organisms. Single-celled organisms, also known as unicellular organisms, consist of a single cell that carries out all the necessary functions of life.

Figure 3: A spiral form of bacteria as observed under the microscope after staining. Image Credit: Microbehunter.

Image Credit: Oklahoma Biological Survey. The study of plants and the cell theory have an intertwined history that dates back to the groundbreaking discoveries of Robert Hooke.

This marked the initial discovery of cells and it laid the foundation for future research in plant biology. The cell theory’s discovery was initiated by Robert Hooke’s observations of cork cells which eventually led to the understanding that all plants consist of cells.

It remains a vital concept in modern plant sciences that guide research and enhance our understanding of the complexities and wonders of plant life. The cell theory’s validity in plants is well-established and remains a fundamental principle in understanding plant structure and function.

But all cells of plants, whether they are the cells that constitute the leaves or the root, follow cell theory. Image Credit: IGCSE.

In sexual reproduction, the union of male and female gametes (specialized reproductive cells) leads to the formation of a new life i.e. a zygote.

This explains all the 3 principles of cell theory (composition, function, and origin). The cell theory is equally applicable and essential in understanding animals, just as it is in plants or other cells.

The unifying principles of cell theory connect the diverse array of animal species. The cell theory’s validity in animals is well-established and remains a fundamental principle in understanding animal structure and function.

Cells are responsible for performing essential functions such as cellular respiration, digestion, and metabolism. This enables animals to extract energy from food and carry out life processes.

From prokaryotes to eukaryotes and from unicellular to multicellular organisms, the tenets of cell theory hold their validity in all of them. Many scientists have contributed to the development and understanding of cell theory the way we know it today.

Data Source: Akanksha Saxena of Biology Online. NOTE IT.

Despite “not fitting” the traditional criteria of living organisms according to the cell theory, viruses are captivating entities that continue to intrigue scientists and molecular biologists. Their unique abilities to interact with host cells and influence evolution make them invaluable subjects of research with potential applications ranging from medicine to cutting-edge biotechnologies.

Some of the notable points of viruses that challenge cell theory are: Take the Cell Theory – Biology Quiz.

Choose the best answer.

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1 Mrs. Degl1 The Cell The Cell Theory: 1.Cells are the basic unit of structure of all living things 2.Cells are the basic unit of function of all living things 3.ALL cells come from pre-existing cells Microscopes have better allowed scientists to develop The Cell Theory.

In 1831, Robert Brown used the word nucleus to describe the dark, central globule. (The word nucleus is Latin for little nut.) Robert Brown Cheek Cells Landmarks in Cell Biology.

Degl2 Exceptions to the Cell Theory : 1.Viruses – are they alive. According to the Cell Theory we have to say “no” because a virus is not a cell.

They appear to be alive when they reproduce after infecting a host cell. 2.

These cell organelles (small structures inside the cell) have their own genetic material & reproduce independently from the rest of the cell. 3.

According to statement #3 of the cell theory, all cells come from other living cells. So how did the first cell ever appear.

We will investigate this question (& its possible answer) in more detail during the Evolution Unit.

Degl3 Animal Cell. 4 Mrs.

5 Mrs. Degl5 Cell Structure and Organelles Most cells possess the same organelles, however plant and animal cells do differ a bit.

6 Mrs.

Degl7 7.Endoplasmic Reticulum System of fluid-filled canals Associated with transport of materials throughout the cell 8.Lysosomes Membrane bounded sacs that contain digestive enzymes Involved in the digestion of food in unicellular organisms Destroys damaged or old cell parts in multi-cellular organisms 9.Vacuoles Fluid filled sacs found in the cytoplasm Contain stored materials, such as food and wastes.

8 Mrs. Degl8 10.Mitochondria Powerhouse of the cell Site where respiration produces energy for the cell Where ATP is produced for energy Contain their own DNA and can duplicate themselves 11.Centrioles Found only in animal cells Located near the nucleus Have a part in cell division 12.Chloroplast Found only in plant cells Contains green chlorophyll pigment Have their own DNA and can replicate Site of Photosynthesis.

Degl9 13.Cilia and Flagella Organelles responsible for cell movement There are usually many cilia on the outside of a cell and they are very small (Paramecium have then There are not many flagella and they are larger (Sperm have them) Flagella. 10 Mrs.

11 Mrs. Degl11 14.Golgi Bodies The Golgi apparatus consists of stacks of sacs with vesicles pinching off from the edges of the sacs.

Also called the Golgi Apparatus or Golgi Complex. 12 Mrs.

13 Mrs. Degl13 Prokaryotic cells have no nucleus or organelles enclosed within membranes.

ArchaeaEubacteria Eukaryotic cells have a nucleus and organelles that are surrounded by membranes. Each organelle does a specific cell function.

Individual protists have only one cell, while plants and animals can have trillions of cells. Complex creatures like humans have special cells for special functions like carrying oxygen around the body, digesting food, or making bone.nucleus and organellesEukaryota domain.

According to the cell theory, all biological organisms are made up of cells, the basic building blocks of life, and all life evolved from preexisting life. It is the cell theory that emphasizes the unity underlying the diversity of forms, i.e., the cellular organization of all life forms.

Schleiden & Schwann were the first to introduce the idea of the cell theory in 1839, and it has remained the cornerstone of modern biology ever since. The cell theory continues to be the dominant theory of biology despite the numerous concepts that ultrastructural research and modern molecular biology have introduced.

The discovery of cells would not have been possible without the advancement of the microscope. Objects that are too small to be seen with the naked eye are magnified with the help of a microscope.

He used a custom-built compound microscope to look at a tiny slice of dry cork that had been cut from a larger piece. He then published a collection of essays under the title Micrographia which described cork as a honeycomb of chambers or “cells”.

The development of a more sophisticated microscope by Anton van Leeuwenhoek in 1673 led to his observation of numerous minute “animalcules” in water. Additionally, he conducted more research on sperm and red blood cells.

Marcello Malpighi and Nehemiah Grew performed in-depth analyses of plant cells and confirmed that cellular structures are present throughout the entire plant body.

In 1838, a German botanist, Matthias Schleiden noticed that all plants are made up of many types of cells that constitute the plant’s tissues after studying many plants.

Based on this, Schwann proposed the hypothesis that the bodies of animals and plants are composed of cells and products of cells. He summarized his observations into three conclusions about cells:

Schwann’s theory also did not explain how new cells were formed.

Therefore, the cell theory states,. With his “swan-neck” experiment in 1865, Louis Pasteur further provided experimental proof in support of Virchow’s extension of the cell hypothesis.

the three basic components of cell theory, plus four additional statements: Understanding the functioning of cells in both healthy and ill conditions paves the way for the creation of novel vaccinations, more potent medications, superior plants, and a greater understanding of how all living things function.

Email Address*. Cell theory does not have a universal application, i.e., certain living organisms do not have true cells.

They lack a plasma membrane and metabolic machinery for energy production and the synthesis of proteins.

All of these organisms have bodies made up of a single, undivided mass of protoplasm that lacks any cellular organization and has several nuclei. Read Also:

If you’re studying biology, you’ll likely learn about the cell theory. The cell theory is one of the most important tenets of biology, and practically everything else you learn in science class relates back to it.

In this guide, we’ll give you a clear cell theory definition, explain key dates in the history of this theory, and explain why it’s so important to understand. After reading this guide, you’ll know everything you need to know about the cell theory.

What is the cell theory. It has three main parts:

All living things are made up of cells. 2.

All cells come from preexisting cells created through the process of cell division. As science evolved, three more components were added to the theory.

Energy flow occurs within cells. 5.

All cells have the same basic chemical composition. So what does the cell theory actually mean.

The first part of the cell theory states that all living things are made up of cells. Anything that’s alive, from bacteria to plants to humans, is composed of cells.

The literal definition is a cell is a group of organelles surrounded by a thin membrane. The cell theory definition states that cells are the building blocks of life.

Your hair, skin, organs, etc. are all made up of cells.

Each part of a cell has a different function, and your cells are responsible for taking in nutrients, turning nutrients into energy, removing waste, and more. Basically, everything your body does, it does because cells are directing the action.

The third part of the cell theory definition states that all cells come from preexisting cells. This means that cells don’t just appear out of thin air (known as “spontaneous generation”).

This means that all current life on the planet is descended from the very first cells, which first made an appearance on Earth roughly 3.5 billion years ago. Cells have been replicating themselves continuously ever since.

Part four refers to the fact that, in all living cells, energy is continuously transformed from one type to another. Examples of these processes include photosynthesis (where plant cells convert light energy into chemical energy) and cellular respiration (where both plant and animal cells convert glucose into energy).

Finally, part six of the cell theory tells us that all cells are made up of the same chemicals: water, inorganic ions, and organic molecules.

The cell theory and ideas about cells and living things evolved over several centuries. Here are the key dates for the cell theory:

1665: Francesco Redi disproves spontaneous generation by showing maggots will only grow on uncovered meat, not meat enclosed in a jar. His work later contributes to part three of the cell theory.

1839: German scientists Matthias Schleiden and Theodor Schwann describe the first two parts of the cell theory. Schleiden stated that all plants are made up of cells, while Schwann stated all animals are made up of cells.

1855: Rudolf Virchow, another German scientist, describes the third part of cell theory, that all cells come from existing cells. Since then, microscopes have continued to become more and more refined, making it possible to study cells even more closely and allowing scientists to expand on the original cell theory.

You may be surprised by how obvious the cell theory seems. Anyone who’s taken a basic biology class already knows what cells are and that living things are made up of cells.

It’s one of the fundamental principles of biology, and it’s so important that it has become information many of us take for granted. Knowing that all living things are made up of cells allows us to understand how organisms are created, grow, and die.

Cells even help us understand fundamental issues such as life and death: an organism whose cells are living is considered alive, while one whose cells are dead is considered dead. Before the cell theory existed, people had a very different view of biology.

An example of this would be a piece of rotten meat creating flies because flies often appear around rotten meat. Additionally, before cells and the cell theory were known, it wasn’t understood that humans, as well as all other living organisms, were made up of billions and trillions of tiny building blocks that controlled all our biological processes.

The cell theory fundamentally changed how we look at life.

It has three main components: 1.

Cells are the basic building blocks of life. 3.

As our scientific knowledge has increased over time, additional parts have been added to the theory. Schleiden and Schwann, as well as Virchow, are generally seen as the founders of the cell theory, due to their pioneering scientific work in the 1800s.

Looking for more cell biology explanations. We have articles on everything from parts of the cell (like nucleotides and the endoplasmic reticulum) to how mitosis works and how it’s different from meiosis.

Then you’re in luck. Our guides will teach you loads of useful topics, including how to convert Celsius to Fahrenheit and what the density of water is.

Check out our guide to learn all the high school classes you should be taking. Are you learning about trig identities in your math classes.

Need more help with this topic. Check out Tutorbase.

Our vetted tutor database includes a range of experienced educators who can help you polish an essay for English or explain how derivatives work for Calculus. You can use dozens of filters and search criteria to find the perfect person for your needs.

Initially, scientists thought that life formed spontaneously on the earth from non-living substances, but experiments and the invention of the microscope shed clarity on this hypothesis, and scientists understood that life and cells originate from preexisting life and cells, respectively. The proposed ‘Principle of Cell Theory’ is the basic principle applied in biology to study cellular events.

Table of Contents. Cells are the basic functional unit of life, and ‘cell theory.

With technological advancement in the microscope, development happened, and scientists began to dig deeper and understand the nature of functional cells and their biological processes. There is always an update as new information emerges.

And cells are the functional and structural unit of life that houses many biomolecules such as carbohydrates, proteins, nucleic acids, lipids, and metabolites in a fluid matrix called cytoplasm enclosed within a plasma membrane. It is of two types:

Continuous upgradation of microscopic equipment led to the discovery of cells and their internal environment. Let’s look at some of the scientists who contributed to the formation of cell theory.

He analyzed and made several observations that he documented in his book ‘Micrographia’, which also includes all the illustrative descriptions of organisms he had studied under his microscope. The cork cells which resembled box shapes reminded hooke of rooms in the monasteries, and he coined the term ‘Cells’, derived from the Latin word ‘cellula’.

Antonie van Leeuwenhoek, a Dutch scientist used to make simple microscopes with only single lenses but with high resolution to study plant tissues and microscopic organisms. He is often known as the ‘father of microbiology,’ and coined the term ‘animalcules’ for freshwater protozoans.

And he observed for the first time, the sperm cells found in humans and animals. They are referred to as the ‘Founders of the Cell Theory’.

He stated “All plants are composed of cells and products of cells” in his literature in 1838. He studied the nucleus and its importance for plant cell division.

Theodore Schwann, a German physiologist used to study animal tissues, and was a good friend of Matthias Schleiden. He proposed that all animal tissues are made of cells that have a nucleus and gave three conclusive statements:

French scientist, François-Vincent Raspail coined ‘Omnis cellula e cellula’, which means ‘all cells come from cells’ was popularized by Rudolf Virchow. He is a German scientist who specializes in the study of diseases and epidemiology.

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The credit for the proposal of the ‘Principle of Cell Theory’ is given to the two scientists, Matthias Schleiden and Theodore Schwann, in the 1830s. This theory has since been updated and modified as new theories and discoveries regarding the cell happen.

This suggests that every function of living organisms from respiration to digestion occurs within a cell. For the growth and development of living organisms, cells reproduce to give rise to new cells by the division of existing cells.

1 Topic 1: Cell Biology 1.1 Introduction to Cells Essential Idea: The evolution of multicellular organisms allowed for cell specialization and cell replacement. 2 Essential Idea The evolution of multicellular organisms allowed cell specialization and cell replacement.

3 Nature of Science Looking for trends and discrepancies – although most organisms conform to cell theory, there are exceptions. Ethical implications of research – research involving stem cells is growing in importance and raises ethical issues.

4 ∑ – According to the cell theory, living organisms are composed of cells. Cell Theory The main part of cell theory consists of three main aspects : 1.Cells are the basic unit of structure in all living things (smallest unit of life) 2.All living organisms are composed of cells.

7 ∑ – According to the cell theory, living organisms are composed of cells. The two scientists given credit to the first two parts of cell theory are Theodor Schwann and Matthias Schlieden (1839).

8 ∑ – According to the cell theory, living organisms are composed of cells. More recently, scientists have added another aspect of the cell theory that states “All cells contain hereditary information (DNA) which is passed on from cell to cell during cell division” Over the years many living organisms, both unicellular and multicellular, have been studied under microscopes and all have been found to be composed of cells.

9 β – Application: Questioning the cell theory using atypical examples, including striated muscle, giant algae and aseptate fungal hyphae. There are exceptions/discrepancies to the cell theory, the following are not made up of typical/regular cells: Exception to General Cell Structure Picture Red Blood Cells are biconcave disks that carry oxygen to different tissues.

10 Exception to General Cell StructurePicture Fungal Cells can have multiple nuclei (multi-nucleated). Fungi have cell walls made out of chitin surrounding threadlike structures called hyphae Aseptate hyphae are one long continuous cell that are not separated by dividers called septa and therefore have many nuclei.

They have a single surrounding membrane, but can contain possibly 100’s of nuclei.

An example of this is Acetabularia, which is a genus of green algae. One would expect a cell of this size would consist of many cells, as it would have difficulty getting rid of metabolic waste.

13 β – Skill: Use of a light microscope to investigate the structure of cells and tissues, with drawing of cells. Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs.

24 Complete Lab Practical 1. 25 ∑ Organisms consisting of only one cell carry out all functions of life in that cell.

b) Response – organisms respond to their environment. c) Homeostasis – maintaining a stable internal environment within the cell.

26 ∑ Organisms consisting of only one cell carry out all functions of life in that cell. d) Growth – increase in size (volume and surface area) until the cell is too large to function efficiently.

f) Nutrition – creating or synthesizing their own organic molecules or consuming organic molecules.

29 ∑ Surface area to volume ratio is important in the limitation of cell size. Cells need to exchange substances with their surroundings, such as food, waste, heat, and gases.

These reactions produce heat, wastes, and also consume resources. The rate of these reactions is proportional to the volume of the cell, while the exchange of these materials and heat energy is a function of the cell’s surface area.

30 ∑ Surface area to volume ratio is important in the limitation of cell size. As the size of an object or a cell increases, its volume increases faster in comparison to the surface area of that object because volume is x³(cubed), while the surface area of an object or cell is only x² (squared).

You can clearly see this by looking at cubes of varying sizes.

34 Time for another Practical How can you use a potato to model differences in surface area to volume ratios.

Paramecium Have a macronucleus and one or more micronuclei. The macronucleus expresses the genes needed to carry out cell activities.

36 ß – Application: Investigation of functions of life in Paramecium and one named photosynthetic unicellular organism. Paramecium The micronuclei contain the genetic material that is passed on asexually to the next generation through binary fission.

37 ß – Application: Investigation of functions of life in Paramecium and one named photosynthetic unicellular organism. Have cilia used for movement Contractile vacuole responsible for expelling water and waste Metabolic reactions catalyzed by enzymes take place in the cytoplasm.

Consume food through an oral groove into the mouth opening ending up in vacuoles. These vacuoles digest the food using enzymes, passing on the nutrients back into the cytoplasm to be used for energy.

39 ß – Application: Investigation of functions of life in Paramecium and one named photosynthetic unicellular organism. The outside is composed of a stiff but elastic membrane called a pellicle, which controls what enters and exits the cell.

40 ß – Application: Investigation of functions of life in Paramecium and one named photosynthetic unicellular organism. Showing paramecium movement, feeding and other life processes Showing paramecium movement, feeding and other life processes.

Chlorella A unicellular organism with a very large chloroplast inside of a cell wall. Converts sunlight energy into a chemical energy form called carbohydrate.

42 ∑ Multicellular organisms have properties that emerge from the interaction of their cellular components. Emergent properties arise from the interaction of component parts, i.e.

Emergence in science and system theories is defined as how complex systems and patterns arise out of a multiplicity of relatively simple interactions. Basically, complex life systems involve millions of small simple interactions that work together to allow the.

Our understanding of cells dates back to the discovery of the microscope, which led to the formulation of the cell theory. The image below shows a detailed timeline that led to the discovery of cell and the cell theory:

However, Schleiden’s theory of spontaneous cell formation was later disapproved by Rudolf Virchow in 1855. He instead stated, ‘Omnis cellula e cellula,’ meaning ‘All cells only arise from pre-existing cells.’ which is included as the third part of the cell theory.

It states that: Since the formation of classical cell theory, further studies on cells with the advancement of microscope have led to the formation of the modern cell theory, which has three main additions:

Its significance lies in its ability to guide research, enable medical advancements, shed light on evolutionary relationships, drive biotechnological innovations, and contribute to ecological and environmental studies. The cell theory has transformed our understanding of biology by recognizing the cell as the fundamental unit of life.

Article was last reviewed on Thursday, July 27, 2023.

1 Topic 1.1 – Introduction to cellsEssential idea: The evolution of multicellular organisms allowed cell specialization and cell replacement.

Check out this awesome thing from Learn.genetics.edu.

μm = micrometers ÷1,000 X 1,000 X 1,000 X 1,000We usually use this in discussion of cells. There are 1,000μm in one mm.

Metric equivalent kilometer km 1,000m 1 x 103m meter m 1m millimeter mm 0.001m 1 x 10-3m micrometer μm m 1 x 10-6m nanometer nm m 1 x 10-9m Use the hints on the side of the table when converting between units. Ex.

How many millimeters is that. 1,267m X (1000mm/1m) = 1,267,000 mm ÷1,000 X 1,000 X 1,000 X 1,000.

5 Skill: Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs.

THE MAGNIFICICENT MAGNIFICATION PYRAMID How to use it: 1. Figure out which of the two variables you have.

Convert them to the same units, if required. (magnification will not have units) 3.

If they are not next to each other, you divide the top one by the bottom one. Size of Image Actual Size of object Magnification.

Let’s figure out how magnified this picture of Ollie the Otter is: Size of Image Magnification Actual Size of object Trying to figure out this. 0.4 m Measure the length of the scale bar.

Convert to the same units. Divide measured length by the actual length in the photograph.

8 Let’s figure out how magnified this picture of Ollie the Otter is: Skill: Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs. Let’s figure out how magnified this picture of Ollie the Otter is: Size of Image Magnification Actual Size of object Trying to figure out this.

Record the length of the scale bar. Convert to the same units.

Example: mm measured length m actual length 3. Conversion: 0.34m x 1000mm/1m = 340mm 4.

9 Let’s figure out how magnified this picture of Ollie the Otter is: Skill: Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs. Let’s figure out how magnified this picture of Ollie the Otter is: Size of Image Magnification Actual Size of object Trying to figure out this.

Go us.

Let’s figure out how magnified this picture of Ollie the Otter is: Size of Image Magnification Actual Size of object 0.34 m Or…. Here’s a shortcut.

Sometimes this will work, other times, not so much. Just keep your eye out.

11 Skill: Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs.

13 Skill: Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs.

15 Skill: Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs.

17 Skill: Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs.

19 Skill: Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs.

Harambe is actually 1.8 meters tall. What is the magnification.

21 A student draws a picture of Harambe, depicting him at 300 mm tallA student draws a picture of Harambe, depicting him at 300 mm tall. Harambe is actually 1.8 meters tall.

Size of Image Magnification Actual Size of object. 22 This image of Tetrahymena was taken through the use of a very powerful light microscope.

What is the magnification and total height of the Tetrahymena in this image.

Focusing a microscope Put the slide on the stage ALWAYS focus at low power first At low power, use the COARSE adjustment knob, then once you have found the image use the fine adjustment knob Increasing Magnification Align the image in the middle of the Field of View Switch to the next highest magnification Use the FINE adjustment knob to bring the image in to focus.

Total Magnification for a Microscope = Eyepiece x Objective Lens Eyepiece – Always 10x for us Objective – 4x, 10x, 40x, 100x. 25 Skill: Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs.

26 Skill: Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs. What you will see when looking through a microscope If the magnification for each of these images is the total magnification, can you identify what objective lens you are looking through for each.

27 According to the cell theory, all living organisms are composed of cells.….or at least one cell. Tetrahymena Protozoan Hooke Schwann These guys were some of the scientists who originally discovered cells, and came up with the cell theory.

All Cells must come from other living cells2. The smallest living thing is a cell.

These functions are: Nutrition Growth Metabolism Reproduction Response Excretion Homeostasis Multicellular organisms have properties that emerge by the interaction of their different cellular components. These are called emergent properties.

A bunch of Liver Cells together make a Liver. Individually, they could not perform all of the functions that they can together 3.

29 Surface area to volume ratio is an important limitation of cell size.In the cytoplasm of the cell, many chemical reactions take place: METABOLISM The rate of these reactions is proportional to the volume of the cell The cell acquires materials for these reactions through the cell membrane. (and excretes as well) Notice.

Rudolf Virchow was not only a brilliant scientist, but he was also involved in politics. Through his combined professions, he was able to make several important changes to the infrastructure and daily life in Berlin.

Begin by having students enter the mindset of Virchow. Have them think about both his personal and professional life.

With this issue in mind, students will research more about what Virchow knew on their selected topic. Then, they will write a letter or speech to the Berlin city council asking them to create a change related to this.

It should use both facts and persuasive language to convince the other members of city council.

My scientific studies have led to extensive studies of the German race and principals surrounding evolution and the differences between races. It is based on this research that I need to make several important announcements on the differences between races, which has been an important topic in recent historical events..

(The student letter would go on to list what the research concluded.). Remind students that since they are writing as Virchow, their document needs to be written from the 1800s and is written from the first-person perspective.

If this is completed in a group setting, students can share their letters or speeches once they have finished.

The defining feature of cell theory is that single cells are the fundamental unit of life and can exist alone or combine to form multicellular organisms.

But how did we reach this understanding. Let’s dive into a short history of cell biology.

Before we get started on the history of cell biology, let’s have a quick refresher on the basic structure of individual cells. Cells come in various types, from prokaryotic cells, such as bacteria and archaea, to eukaryotic plant and animal cells.

These distinct cell types vary in their structures, depending on their cell specialization. However, cell membranes are a defining feature of cells.

They regulate the movement of chemicals across the membrane both in and out of the cell. Most cells also contain genetic material in the form of deoxyribonucleic acid (DNA).

In prokaryotes, there are no intracellular membranes, and the DNA is located in the cytoplasm. Some types of cells with specific functions lack DNA, such as mature red blood cells.

The cell theory, or cell doctrine, states that all organisms are composed of similar basic units of organization called cells. The concept was formally articulated in 1839 by Schleiden & Schwann and has remained as the foundation of modern biology.

While the invention of the telescope made the Cosmos accessible to human observation, the light microscope opened up smaller worlds, showing what living forms were composed of. The cell was first discovered and named by Robert Hooke in 1665.

However, what Robert Hooke actually saw was the dead cell walls of plant cells (cork) as they appeared under the microscope. Hooke’s description of these cells was published in Micrographia.

The first man to witness a live cell under a microscope was Anton van Leeuwenhoek, who, in 1674, described the algae Spirogyra. Van Leeuwenhoek probably also saw bacteria.

It has been suggested that when Schwann heard Matthias Schleiden describe plant cells with nuclei, he was struck by the similarity of these plant cells to animal cells he had observed in tissues. The two scientists went immediately to Schwann’s lab to look at his slides.

He summarized his observations into three conclusions about cells: We know today that the first two tenets are correct, but the third is clearly wrong.

As with the rapid growth of molecular biology in the mid-20th century, cell biology research exploded in the 1950s. It became possible to maintain, grow, and manipulate cells outside of living organisms.

The cell line, which was eventually referred to as HeLa cells, has been the watershed in studying cell biology in the way that the structure of DNA was the significant breakthrough of molecular biology. In an avalanche of progress in the study of cells, the coming decade included the characterization of the minimal media requirements for cells and the development of sterile cell culture techniques.

The study of the structure and function of cells continues today in a branch of biology known as cytology. Advances in equipment, including cytology microscopes and reagents, have allowed this field to progress, particularly in the clinical setting.

1595 – Jansen is credited with the first compound microscope.1655 – Hooke described ‘cells’ in cork.1674 – Leeuwenhoek discovered protozoa. He saw bacteria some nine years later.1833 – Brown described the cell nucleus in cells of the orchid.1838 – Schleiden and Schwann proposed cell theory.1840 – Albrecht von Roelliker realized that sperm cells and egg cells are also cells.1856 – N.

Cambridge Instruments produced the first commercial scanning electron microscope.1976 – Sato and colleagues publish papers showing that different cell lines require different mixtures of hormones and growth factors in serum-free media.1981 – Transgenic mice and fruit flies are produced.

2009 – First paper published using organoids derived from a single adult stem cell.2012 – CRISPR gene editing is developed, allowing precise RNA-targetted genome engineering.

Read our article on how to turn a mobile phone into a simple microscope to appreciate how accessible the cellular world is. Originally published November 2007.

1 Cells Unit 3 & 4. 2 Cell Theory All living things are made of cells2.

All cells come from preexisting cells organism Organ system Organ cells tissue Skin Cell Muscle Cell Muscle Cell Skin Cell Muscle Cell Skin Cell. 3 Shape & Function Cells are specialized so they can perform different jobs.

4 Cell Structure and FunctionCells vary in size, shape & function. Smallest – bacteria cell Largest – Ostrich egg Longest Cell – Neurons/nerve cells.

EukaryotesProkaryotic cells – __________, no nucleus and no ___________________________ organelles. Ex: ___________________________ Eukaryotic cells – ______________, have a DNA filled _____________ and membrane bound organelles.

6 DNA CYTOPLASM RIBOSOMESNo matter what, all cells have 4 organelles in common: _________________________________ CELL MEMBRANE DNA CYTOPLASM RIBOSOMES. 7.

9 Animal Cells vs. Plant CellsPlant cells have ______________________ Plant cells have _______________________ Animal cells have _____________ for breaking down waste.

11 Cell Wall Location: Plants, Fungi, some bacteriaFunction: Rigid structure outside of cell membrane for extra support Cell Membrane Cell Wall. 12 Cell Membrane Location: ALL CELLS.

maintains homeostasis Cell Membrane Cell Wall. 13 Vacuole Location: All eukaryotes, bigger in plants.

14 Chloroplast Location: Plants only. Function: Site of photosynthesis (production of glucose).

Has folded membrane for increased surface area.

Nucleolus: Site of ribosome production. DNA Nucleolus.

ALL CELLS. Function: Site of protein synthesis (production).

10 minutes. 19 Cell Adaptations Pseudopod: extensions of cytoplasm that are used for movement & feeding Eyespot: Organelle that detects light which is needed for chloroplasts to do photosynthesis.

20 Cell Adaptations Contractile Vacuole: structure that helps remove excess water from the cell Cilia: Short hair-like projections from the membrane that help the cell move. 21 Cell Adaptations Flagella: Long whip-like structure that extends from the cell membrane.

(usually one or two per cell). 22 Plant Cells vs Animal Cellschloroplasts nucleus ribosomes No cell wall Membrane bound organelles large central vacuole cell membrane cytoplasm Small vacuoles mitochondria cell wall eukaryotic.

ArmCoarse Adjustment K. Base G.

Eyepiece/ocular lens Answer Questions using Parts Used to bring objects into focus on the low power Used to carry the microscope Turned to clear blurry pictures, used on high power Calculating Total Magnification: Multiply the ocular lens by the objective lens Ocular = 10 x Objective = 4x 4 x 10 = D K, H A 40x.

Complete Questions. Make sure you can write the equations without looking.

Complete Chart and Questions Go back to your HW chart and correct/fill in 10 minutes. 25 Make sure your homework is out to be checked.

Today is worth 40 points (10 accuracy & 30 participation) HW: Study. Resources online.

26 Membrane/Transport Rotations10 points possible as a TWO Table Group. No outside resources.

(5 minutes) ROTATE.

Work with your table to CHECK and/or CORRECT the answers from the previous table. Answer any unanswered questions with the assigned color (8 minutes) RETURN.

Check over all work to turn in. (5 min).

What are types of Active Transport. Complete the Word Sort and add notes of unfamiliar terms Osmosis Diffusion Facilitated Diffusion Active Transport Requires Cellular ATP.

Uses an embedded protein.

Do not use any resources other than your brain. 20 minutes Snack and Break.

32 Released Items Number # 21-40For each question write the letter answer. Do not use any resources other than your brain.

33 Cell Cycles Mitosis and Meiosis Comparison Do you know these terms. Somatic Cells Law of Segregation Law of Independent Assortment Crossing Over.

Modern cell theory isn’t all that modern when you understand how long ago it originated. With roots in the mid-17th century, multiple scientific scholars and researchers of the day contributed to the tenets of classical cell theory, which postulated that cells represent the basic building blocks of life.

The classical interpretation of modern cell theory begins with the premise that all life consists of one or more cells, cells represents the basic building blocks of life, all cells result from the division of pre-existing cells, the cell represents the unit of structure and arrangement in all living organisms and finally that the cell has a dual existence as a unique, distinctive entity and as a fundamental building block in the framework of all living organisms.

Hooke published his findings in 1665 in his book, “Microphagia,” which included hand-sketched drawings of his observations. Hooke discovered plant cells when he examined a thin slice of cork through the lens of his converted compound microscope.

He called them “cells,” and the name stuck. Dutch scientist Antony van Leeuwenhoek (1632-1705), a tradesman by day and a self-driven biology student, ached to discover the secrets of the world around him, and even though not formally educated, he ended up contributing important discoveries to the field of biology.

Leewenhoek’s studies brought a new level of awareness of microscopic life to scientists of the day, spurring others on who would, in the end, play a part in contributing to modern cell theory.

(For Schwann, Schleiden and Virchow see and Scientists, biologists, researchers and scholars, though still using the fundamental tenets of cell theory, conclude the following on the modern interpretation of cell theory: Scientists have traced back all life to a single, common unicellular ancestor that lived approximately 3.5 billion years ago, first proposed by evolutionist Charles Darwin more than 150 years ago.

In an article on the “National Geographic” website, he says the odds of that happening are astronomical, something like 1 in 10 to the 2,680th power. He came to this conclusion after calculating the odds using statistical processes and computer models.

People are a jumble of 37.2 trillion cells. But all humans, like every other living entity on the planet, began life as a single-cell organism.

The cell continues to divide exponentially during the days the embryo travels from the human fallopian tube to implant itself inside the womb, where it continues to grow and divide. While there are certainly smaller things inside the body than living cells, the individual cell, like a Lego block, remains a basic unit of structure and function in all living organisms.

In biology, there are two types of cells: prokaryotes and eukaryotes. Prokaryotes represents cells without a nucleus and membrane-enclosed organelles, though they do have DNA and ribosomes.

Eukaryotes on the other hand, have a nucleus inside the cell and bound within a separate membrane, as well as membrane-enclosed organelles. Eukaryotic cells also have something prokaryotic cells do not: organized chromosomes for retaining genetic material.

Scholars call this process mitosis – cell division – because one cell produces two new genetically identical daughter cells. While mitosis occurs after sexual reproduction as the embryo develops and grows, it also occurs throughout the lifespan of a living organisms to replace old cells with new cells.

In the break between cell division, interphase represents part of the cell-cycle phase where a cell pauses and take a break. This allows the cell to develop and double its internal genetic material as it gets ready for mitosis.

When combined, these reactions make up the cell’s metabolism. During this process, some chemical bonds in the reactive molecules get broken, and the cell takes in energy.

Exergonic reactions occur when the cell releases energy to its surroundings, forming stronger bonds than the ones broken. In endergonic reactions, energy comes into the cell from its surroundings, creating weaker chemical bonds than the ones broken.

As DNA is the carrier of genetic data, the information stored in the original cell’s DNA duplicates in daughter cells. The DNA provides a blueprint for the final development of the cell, or in the case of eukaryotic cells in the plant and animal kingdoms, for example, the blueprint for the multicellular life form.

They use the Linnaean taxonomy system to rank all living creatures by domain, kingdom, phylum, class, order, family, genus and species. By doing this, biologists learned that in organisms of similar species, individual cells contain basically the same chemical composition.

Some scientists consider this colony as multicellular, but the individual cells don’t require the colony to live and function. Living organisms categorized under the Bacteria and Archaea domains are all single-celled organisms.

All living cells in the Bacteria and Archaea domains consist of single-celled organisms. Under the Eukarya domain, living organisms in the Protista kingdom are single-celled organisms with a separately identified nucleus.

Other kingdoms under the domain Eukarya include Fungi, Plantae and Animalia. Yeast, in the Fungi kingdom, are single-celled entities, but other fungi, plants and animals are multicellular complex organisms.

In multicellular organisms, like the human being, cells develop differently, each with their individual and independent tasks. Some cells group together to become the brain, the central nervous system, the bones, muscles, ligaments and tendons, major body organs and more.

Blood cells, for example, function on many levels, carrying oxygen to needed parts of the body. fighting pathogens, bacterial infections and viruses.

Disease occurs when one or more of these functions break down. Scientists, biologists and virologists all don’t agree on the nature of viruses because some experts consider them as living organisms, yet they do not contain any cells whatsoever.

Viruses are the zombies of the biological world. Living in a no-man’s land in a gray area between life and death, when outside the cells, viruses exist as a capsid encased in a protein shell or as a simple protein coat sometimes enclosed inside a membrane.

1 The History of the Cell TheoryObjective: I will be able to explain the components of the cell theory and the historical persons and events that led to its development.

3 Cell Theory Part 1 Why do they compare the building of city to that of a human body. In a human body what is analogous to the bricks in a city) According to the video what are the smallest part of living things.

Fill in the following sequence : cells > _________ > organs > __________ > organism. Without bricks it would be very difficult to build and repair a city.

July 22, 2012 Footer text here. 4 Cell Theory Part 2 As you watch the video, sketch what you see.July 22, 2012 Footer text here.

Based on the picture above what are the two type of organisms that exist. Are plants and animals multicellular or unicellular.

Could you infer from the figure that bacteria are living. Why do you think this.

6 Scientists can only make discoveries in a laboratory with white lab coats and science gizmos that go beep. July 22, 2012 Footer text here.

There are three parts to the cell theory2. There are three parts to the cell theory.

All organisms are composed of one or more cells. The cell is the basic unit of structure and organization in organisms.

All cells come from pre-existing cells. July 22, 2012 Footer text here.

Anton van Leeuwenhoek made his own version of the microscope and discovered something very odd when he looked at the gunk on his teeth. What did he discover.

Who named the cell. Robert Hooke Robert Redford Robert SmithRobert DeNiro July 22, 2012 Footer text here.

Which scientist realized that, by studying samples under a microscope, all animals are made up of cells. Rudolf Virchow Robert Ramak Theodor Schwann Isaac Newton July 22, 2012 Footer text here.

2) What observations did you make during the microscope activity that provides evidence for what the cell theory states. 3) Name at least three scientists and explain their contribution to the development of the cell theory.

12 The End.

In biology, cell theory is a scientific theory first formulated in the mid-nineteenth century, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells. Cells are the basic unit of structure in all living organisms and also the basic unit of reproduction.

Cell theory has traditionally been accepted as the governing theory of all life, but some biologists consider non-cellular entities such as viruses living organisms[citation needed] and thus disagree with the universal application of cell theory to all forms of life.

This discovery is largely attributed to Robert Hooke, and began the scientific study of cells, known as cell biology. When observing a piece of cork under the scope, he was able to see pores.

To further support his theory, Matthias Schleiden and Theodor Schwann both also studied cells of both animal and plants. What they discovered were significant differences between the two types of cells.

The discovery of the cell was made possible through the invention of the microscope. In the first century BC, Romans were able to make glass.

The expanded use of lenses in eyeglasses in the 13th century probably led to wider spread use of simple microscopes (magnifying glasses) with limited magnification. Compound microscopes, which combine an objective lens with an eyepiece to view a real image achieving much higher magnification, first appeared in Europe around 1620.

Hooke also used a simpler microscope with a single lens for examining specimens with directly transmitted light, because this allowed for a clearer image.

At some point in his life before 1668, he was able to learn how to grind lenses. This eventually led to Leeuwenhoek making his own unique microscope.

He was able to use a single lens that was a small glass sphere but allowed for a magnification of 270x. This was a large progression since the magnification before was only a maximum of 50x.

Carl Zeiss, a German engineer who manufactured microscopes, began to make changes to the lenses used. But the optical quality did not improve until the 1880s when he hired Otto Schott and eventually Ernst Abbe.

Optical microscopes can focus on objects the size of a wavelength or larger, giving restrictions still to advancement in discoveries with objects smaller than the wavelengths of visible light. The development of the electron microscope in the 1920s made it possible to view objects that are smaller than optical wavelengths, once again opening up new possibilities in science.

The cell was first discovered by Robert Hooke in 1665, which can be found to be described in his book Micrographia. In this book, he gave 60 observations in detail of various objects under a coarse, compound microscope.

Hooke discovered a multitude of tiny pores that he named “cells”. This came from the Latin word Cella, meaning ‘a small room’ like monks lived in, and also Cellulae, which meant the six-sided cell of a honeycomb.

What Hooke had thought were cells, were actually empty cell walls of plant tissues. With microscopes during this time having a low magnification, Hooke was unable to see that there were other internal components to the cells he was observing.

His cell observations gave no indication of the nucleus and other organelles found in most living cells. In Micrographia, Hooke also observed mould, bluish in color, found on leather.

This led to Hooke suggesting that spontaneous generation, from either natural or artificial heat, was the cause. Since this was an old Aristotelian theory still accepted at the time, others did not reject it and was not disproved until Leeuwenhoek later discovered that generation was achieved otherwise.

Anton van Leeuwenhoek is another scientist who saw these cells soon after Hooke did. He made use of a microscope containing improved lenses that could magnify objects 270-fold.

In a letter to The Royal Society on October 9, 1676, he states that motility is a quality of life therefore these were living organisms. Over time, he wrote many more papers which described many specific forms of microorganisms.

Though he did not have much formal education, he was able to identify the first accurate description of red blood cells and discovered bacteria after gaining interest in the sense of taste that resulted in Leeuwenhoek to observe the tongue of an ox, then leading him to study “pepper water” in 1676. He also found for the first time the sperm cells of animals and humans.

This put an end to the previous theory of spontaneous generation. After reading letters by Leeuwenhoek, Hooke was the first to confirm his observations that were thought to be unlikely by other contemporaries.

Cells in animal tissues were observed later than those in plants because their tissues are fragile and difficult to study. Biologists believed that there was a fundamental unit to life, but until Henri Dutrochet were unclear what it was.

In 1804, Karl Rudolphi and J. H.

Link were awarded the prize for “solving the problem of the nature of cells”, meaning they were the first to prove that cells had independent cell walls by the Königliche Societät der Wissenschaft (Royal Society of Science), Göttingen. Before, it had been thought that cells shared walls and the fluid passed between them this way.

Credit for developing cell theory is usually given to two scientists: Theodor Schwann and Matthias Jakob Schleiden. While Rudolf Virchow contributed to the theory, he is not as credited for his attributions toward it.

He also suggested that cells were made by a crystallization process either within other cells or from the outside. However, this was not an original idea of Schleiden.

This crystallization process is no longer accepted with modern cell theory. In 1839, Theodor Schwann states that along with plants, animals are composed of cells or the product of cells in their structures.

From these conclusions about plants and animals, two of the three tenets of cell theory were postulated.

In 1855, Rudolf Virchow added the third tenet to cell theory. In Latin, this tenet states Omnis cellula e cellula.

However, the idea that all cells come from pre-existing cells had already been proposed by Robert Remak. it has been suggested that Virchow plagiarized Remak.

He instead said that binary fission, which was first introduced by Dumortier, was how reproduction of new animal cells were made. Once this tenet was added, classical cell theory was complete.

The generally accepted parts of modern cell theory include:. The cell was first discovered by Robert Hooke in 1665 using a microscope.

In this theory the internal contents of cells were called protoplasm and described as a jelly-like substance, sometimes called living jelly. At about the same time, colloidal chemistry began its development, and the concepts of bound water emerged.

The term osmosis originated in 1827 and its importance to physiological phenomena realized, but it wasn’t until 1877, when the botanist Pfeffer proposed the membrane theory of cell physiology. In this view, the cell was seen to be enclosed by a thin surface, the plasma membrane, and cell water and solutes such as a potassium ion existed in a physical state like that of a di.

1.1.1. in bone marrow.

in bone marrow transplants to treat people who have certain types of cancer. 1.3.1.

1.3.2. the normal cells in the bone marrow.

He can undergo a bone marrow harvest in which stem cells are removed from the bone marrow by using a needle which is inserted into the hip bone. 1.4.2.

1.4.2.1. Stem cells can be harvested from a matching donor.

6.2.1. 10 nm.

100 nm. 6.4.1.

6.5.1. up to100 μm.

up to 10 μm. 7.2.1.

8.1.1. If the surface area to volume ratio gets too small then substances won’t be able to enter the cell fast enough to fuel the reactions and waste products will start to accumulate within the cell as they will be produced faster than they can be excreted.

Take measurement of the drawing (width or length). 10.1.2.

Take the same measurement from the specimen. 10.1.3.

Convert units. 10.1.4.

10.1.4.1. Magnification = Image size/actual size.

Image size = actual size x magnification. 10.1.4.3.

1 Lecture 3: The Cell The Cell Theory The cell theory states that:In 1838, the German botanist Matthias Schleiden concluded that all plants were composed of cells In 1839, Theodor Schwann concluded the same thing for animals In 1855, Rudolf Virchow noted that all cells come from other cells The cell theory states that: all living organisms are made of one or more cells, cells are the basic units of structure and function, and cells come only from pre-existing cells.

2 All Protists, Fungi, Plants and AnimalsTypes of cells بدائية النواة حقيقية النواة Prokaryotes Eukaryotes Bacteria and Archaea All Protists, Fungi, Plants and Animals. 3 Prokaryotic and eukaryotic cellsA) Similarities أوجه التشابه All cells are surrounded by a plasma membrane غشاء بلازمى.

All cells contain chromosomes which have genes in the form of DNA. All cells have tiny organelles عضيات صغيرة called “Ribosomes” that make proteins.

4 Prokaryotic and eukaryotic cellsB) Differences أوجه الإختلاف A major difference الفرق الأساسي between prokaryotic and eukaryotic cells is the location of chromosomes موضع الصبغيات In an eukaryotic cell, chromosomes are contained in a true nucleus (النواة) with nuclear membrane غشاء نووي. In a prokaryotic cell, the DNA is concentrated in the nucleoid (شـبه نواة) without a nuclear membrane separating it from the rest of the cell.

5 Comparison between Prokaryotes and EukaryotesTerm Prokaryotes Eukaryotes Size 1-10 µm in diameter µm in diameter Cell wall Existed In plant cell (not animal cell) nucleus No nuclear membrane but Nucleoid True nucleus exists with nuclear membrane DNA As fibre in the nucleoid region (plasmids in some cases) As Chromatin (DNA and protein) Specializeorganells Most of them are absent All are existed Cell division By binary fission Meiotic and/or Mitotic.

7 Bacteria. 8 شبه نواة الريبوزومات غشاء بلازمى الجدار الخلوى الكبسولة الأسواط The prokaryotic cell is much simpler in structure, lacking a nucleus and the other membrane-enclosed organelles of the eukaryotic cell.

9 Prokaryotic Cell Plasma membrane Cell Wall Capsule Ribosomes NucleoidCytoplasm (Cytosol). 10 Eukaryotes An eukaryotic cell has internal membranes, which partition تـُقـَســم the cell into compartments أجزاء مستقلة.

The general structure of a biological membrane is a double layer ثنائي الطبقات of phospholipids and diverse proteinsبروتينات متنوعة. Each type of membrane has a unique combination تركيب مـُمـَيـٍز of lipids and proteins for its specific functions.

11 Eukaryotes Animal Cell Plant CellEu: True Karyon: Nucleus Animal Cell Plant Cell Compare between Animal and Plant cell. What are the functions of cell organelles.

12 الشبكة الإندوبلازمية الكروماتين نوية النواة سوط حركى الغلاف النووى خشنه ناعمه جسم مركزى ريبوسوم حهاز جولـﭽـي حلمات دقيقة غشاء بلازمي ميتوكوندريا جسم مُحلل الهيكل الخلوى. 13 فجوة مركزية بلاستيدة خضراء الجدار الخلوى ثقوب بينية.

The smallest units of life, cells, are described by the Modern Cell Theory. It is composed of several points, such as that all living things are composed (made) of a cell (single-celled) or multiple cells (multicellular).

Next, every existing cell comes from older cells that reproduced. Finally, cells perform the functions that sustain life.

If a cell is a prokaryote, then the cell is much simpler, and it will not have a nucleus. A eukaryotic cell, on the other hand, does have a nucleus, along with other organelles that help the cell to function.

The cell membrane is the thin skin that controls what goes in and out of the cell, such as food and waste products. In the case of plant cells, the cell membrane is supported and protected by a cell wall.

These items include the organelles that perform the cell’s functions, such as chloroplasts in plants, which gather energy from the sun for photosynthesis, mitochondria, which act as “power plants” in cells, and the endoplasmic reticulum, which works to fold and move proteins in the cells.

The nucleus contains most the cell’s DNA, which is the genetic material that acts as the recipe with which the cell was made, and from which new cells will be made. Other organelles are the centrioles, which work to keep the cell organized by forming spindles when a cell divides, the nucleolus, an organelle inside the nucleus that prepares the RNA that acts as the recipe for ribosomes, which produces protein for the cells.

When teaching students about Life Science (Biology), one way to teach students to use a microscope is to take a sample of water from a pond or lake and observe the tiny organisms that are swimming in the water. An example of a much larger cell is the yolk, or yellow part of an egg.

When a group of cells that work together to perform the same task are tissues. If two or more tissues work together, they form an organ.

A collection of organs and tissues that are working together create an organ system. Continuing with the skin example, the integumentary system include that organ along with other parts of the body that help protect it from wear and tear.

Endosymbiotic theory n., [ˌɛndəʊˌsɪmbɪˈəʊt.ɪk ˈθɪɚ.i] Definition: a theory proposing that the origin of organelles in eukaryotic cells is based on early endosymbiosis. Table of Contents.

And based on this theory, the organelles mitochondria and chloroplasts are supposedly the early prokaryotic endosymbionts that had been taken in. They stayed inside the host cell for so long that they transitioned into those semi-autonomous organelles we know today.

It is a presumption that an endosymbiosis occurred between the early life forms. This form of symbiosis involves a larger cell that serves as a host and a smaller cell that is referred to as an endosymbiont.

The larger cell represents the eukaryotic cell of today whereas the smaller cell is the prokaryotic cell. Watch this vid about endosymbiotic theory:

In endosymbiosis, the endosymbiont lives within the body of its host. Endosymbiosis naturally occurs to this day.

Rhizobium is the endosymbiont that occurs within the roots of legumes and fixes atmospheric nitrogen into a form that is ready for use by the legume. The legume, in turn, provides Rhizobium metabolites such as malate and succinate from photosynthesis.

According to the Endosymbiotic Theory, endosymbiosis became the means by which organelles such as mitochondria and chloroplasts within eukaryotic cells came about.1 Proponent of this theory posited that about 1.5 billion years ago a larger cell took in smaller free-living prokaryotes (bacteria) and inside the cell the prokaryotes lived as endosymbionts.

The indication that this theory is plausible is based upon the same features shared by these organelles and their prokaryotic ancestors. Some of the characteristics common to them are as follows:

The modern theory of abiogenesis holds that life on Earth began when the earliest living entities took in non-living materials. They used these organic compounds to produce biomolecules and other building blocks of life.

self-replication, self-assembly, autocatalysis, and cell membrane formation, probably led to the emergence of living entities. These processes were believed to be gradual and comprised of multiple events.

Mixing gases methane, ammonia, hydrogen, and water and then electrically-sparking them resulted in the formation of amino acids. Around four billion years ago, the Earth was hostile to life.

Eventually, simple organic compounds formed. The hypothetical model of the early Earth with conditions that led to the synthesis of simple organic compounds is called the prebiotic (primordial) soup.

Both of them theorized that the early Earth’s atmosphere was a chemically reducing atmosphere. It aided in producing such organic compounds.

Through time, these simple organic compounds transformed into more complex organic polymers. In the long run, life came about.

They theorized that the first forms of life were heterotrophic. Recent evidence, though, suggests that autotrophs are likely the first organisms.

RNA, DNA), carbohydrates (various sugars), lipids (fats), and amino acids (constituents of proteins). Primitive life is hypothesized to be RNA-based since RNA could be both genetic material and a catalyst.

Take the Quiz on Endosymbiotic Theory.

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All living organisms, including humans, animals, and plants, are made up of cells. Cells are the fundamental units of life, serving as the structural, functional, and biological building blocks of all living organisms.

While microscopic life forms are often composed of a single cell, larger organisms consist of millions of cells. Cells contain the hereditary material of organisms which is necessary for the growth, development, and functioning of living beings.

The discovery of cells began with Robert Hooke’s observation of dead plant cell walls in cork under a microscope in 1665. Later in 1674, Anton van Leeuwenhoek used a more powerful compound microscope and observed cells with higher magnification.

He termed them “animalcules” based on his observations. Later, in 1833, Robert Brown, a Scottish botanist, described the nucleus present in the cells of orchids.

Table of Contents. The cell theory is a fundamental concept in biology stating that all organisms are made up of basic units called cells.

Scientists such as Matthias Schleiden, Theodor Schwann, and Rudolf Virchow contributed to the formulation of cell theory.

Schleiden proposed the theory for plant cells, while Schwann extended it to all living organisms, including animals. Later, Rudolf Virchow further emphasized cell theory in his work.

Virchow’s contributions solidified the cell theory. The modern cell theory builds on the original cell theory proposed by Schleiden, Schwann, and Virchow.

Cells can be broadly categorized into two types: prokaryotic cells and eukaryotic cells. Each type contains unique structures and functions, contributing to the diversity of living organisms.

Eukaryotic cells come in different types, each specialized for specific functions. Some types of eukaryotic cells are:

Email Address*. The human body contains hundreds of cell types, each with its own specific functions and characteristics.

Some of these major cells are: Blood is a fluid connective tissue that has both cellular and liquid components.

The cellular components of blood include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes). Red blood cells facilitate the transport of oxygen from the lungs to tissues and carry carbon dioxide back.

Platelets play an important role in the process of blood clotting. Bones are a significant component of the skeletal system.

Cancer cells are abnormal cells characterized by uncontrolled growth and division. Cancer cells can develop from genetic mutations caused by exposure to various factors, including chemicals, radiation, ultraviolet light, and cancer-causing viruses.

Cartilage is a connective tissue characterized by its solid matrix and lack of blood supply. Cartilage provides structural support to many parts of the body.

Endothelial cells are a specialized type of cells that form the inner lining of the cardiovascular system and lymphatic system. Endothelial cells are present in various organs, such as the brain, lungs, skin, and heart, where they contribute to the structure and function of the vascular network.

Endothelial cells also produce substances that help manage blood pressure.

Fat cells store energy in the form of triglycerides. When the body needs extra energy, such as during fasting or increased physical activity, fat cells release stored triglycerides.

Egg cells are the female reproductive cells that play a central role in sexual reproduction and the formation of new organisms. The formation of egg cells is called oogenesis.

The primary function of the egg cell is to fuse with a sperm cell during fertilization which results in the formation of a zygote. Fertilization combines the genetic material from both the egg and the sperm, leading to the formation of a genetically unique individual.

Sperm cells are the male reproductive cells responsible for fertilizing the female egg and initiating the process of sexual reproduction. One of the distinctive features of sperm cells is the presence of a long tail called a flagellum which allows sperm to move through the female reproductive tract toward the egg.

The head of the sperm contains structures called acrosomes which release enzymes that help the sperm to penetrate the layers surrounding the egg. Sperm cells are formed through a process called spermatogenesis.

Muscle cells group together to form muscle tissue which is responsible for all bodily movements. The three types of muscle cells are:

Structurally, neurons consist of a central cell body containing the nucleus, cytoplasm, and organelles. Additionally, they have extensions known as axons and dendrites, which are finger-like projections extending from the cell body.

The pancreas serves a dual role as an exocrine and endocrine organ. In its exocrine function, the pancreas produces cells that secrete digestive enzymes that play a crucial role in breaking down proteins, carbohydrates, and fats during digestion.

These endocrine cells release hormones directly into the bloodstream to regulate blood glucose levels and other metabolic processes.

The top layer is the epidermis, made up of flat, squamous epithelial cells. Below the epidermis is the dermis, which provides structural support.

The skin has diverse functions, serving as a protective barrier against physical damage, dehydration, and harmful microbes.

Stem cells begin as unspecialized cells which do not have a specific function, and possess the ability to differentiate into specialized cells that make up various organs and tissues in the body. This allows them to potentially develop into cells of the heart, liver, skin, or any other tissue.

Stem cells have potential therapeutic applications. Read Also:

Cells contain a special collection of molecules that are enclosed by a membrane. These molecules give cells the ability to grow and reproduce.

During cell growth, the cell ingests certain molecules from its surroundings by selectively carrying them through its cell membrane. Once inside the cell, these molecules are subjected to the action of highly specialized, large, elaborately folded molecules called enzymes.

These chemical alterations make the molecules more useful to the cell. Unlike the ingested molecules, catalysts are not chemically altered themselves during the reaction, allowing one catalyst to regulate a specific chemical reaction in many molecules.

In other words, a molecule chemically transformed by one catalyst serves as the starting material, or substrate, of a second catalyst and so on. In this way, catalysts use the small molecules brought into the cell from the outside environment to create increasingly complex reaction products.

Once the genetic material has been copied and there are sufficient molecules to support cell division, the cell divides to create two daughter cells. Through many such cycles of cell growth and division, each parent cell can give rise to millions of daughter cells, in the process converting large amounts of inanimate matter into biologically active molecules.

In evolutionary biology, the term cellularization (cellularisation) has been used in theories to explain the evolution of cells, for instance in the pre-cell theory, dealing with the evolution of the first cells on this planet, and in the syncytial theory attempting to explain the origin of Metazoa from unicellular organisms.

Processes of cell development in multinucleate cells (syncytium, plural syncytia) of animals and plants are also termed cellularization, often called syncytium cellularization.

According to Otto Kandler’s pre-cell theory, early evolution of life and primordial metabolism (see Iron-Sulfur world hypothesis – metabolism first scenario, according to Wächtershäuser ) led to the early diversification of life through the evolution of a multiphenotypical population of pre-cells, from which the three founder groups A, B, C and then, from them, the precursor cells (here named proto-cells) of the three domains of life emerged successively.

In this scenario the three domains of life did not originate from an ancestral nearly complete “first cell“ nor a cellular organism often defined as the last universal common ancestor (LUCA ), but from a population of evolving pre-cells. Kandler introduced the term cellularization for his concept of a successive evolution of cells by a process of evolutionary improvements.

His concept may explain the quasi-random distribution of evolutionarily important features among the three domains and, at the same time, the existence of the most basic biochemical features (genetic code, set of protein amino acids etc.) in all three domains (unity of life), as well as the close relationship between the Archaea and the Eucarya.

According to Kandler, the protection of fragile primordial life forms from their environment by the invention of envelopes (i.e. membranes, walls) was an essential improvement.

A coevolution of the biosphere and the geosphere is suggested: “The evolving life could venture into a larger variety of habitats, even into microaerobic habitats in shallow, illuminated surface waters.

: 155f. The details of Kandler’s proposal for the early diversification of life are represented in a scheme, where numbers indicate evolutionary improvements.

This theory is also known as a theory of cellularization. It is a theory to explain the origin of the Metazoa.

This cellularization (syncytial) theory states that metazoans evolved from a unicellular ciliate with multiple nuclei that went through cellularization. Firstly, the ciliate developed a ventral mouth for feeding and all nuclei moved to one side of the cell.

In this way, a multicellular organism was created from one multinucleate cell (syncytium).

The theory of cellularization is based on the large similarities between ciliates and flatworms. Both ciliates and flatworms have cilia, are bilaterally symmetric, and syncytial.

However, current biological evidence shows that the most primitive forms of metazoans show radial symmetry, and thus radially symmetrical animals like cnidaria cannot be derived from bilateral flatworms.

However, most current molecular research has shown that sponges are the most primitive metazoans.

During the development of the turbellaria (Acoela), three regions are formed without the formation of germ layers. From this, it was concluded that the germ layers are simultaneously formed during the cellularization process.

There is a lot of evidence against ciliates being the metazoan ancestor. Ciliates have two types of nuclei: a micronucleus which is used as germline nucleus and a macronucleus which regulates the vegetative growth.

Therefore, it would be unlikely that ciliates are indeed the ancestors of the metazoans. This is confirmed by molecular phylogenetic research.

Furthermore, the syncytial theory cannot explain the flagellated sperm of metazoans. Since the ciliate ancestor does not have any flagella and it is unlikely that the flagella arose as a de novo trait in metazoans, the syncytial theory makes it almost impossible to explain the origin of flagellated sperm.

Due to both the lack of molecular and morphological evidence for this theory, the alternative colonial theory of Haeckel, is currently gaining widespread acceptance.

The development of cells in a syncytium (multinucleate cells) is termed syncytium cellularization. Syncytia are quite frequent in animals and plants.

Here two examples:. In the embryonic development of Drosophila melanogaster, first 13 nuclear divisions take place forming a syncytial blastoderm consisting of approximately 6000 nuclei.

The term syncytium cellularization is used for instance for a process of cell development in the endosperm of the Poaceae, e.g. barley (Hordeum vulgare), rice (Oryza sativa).

The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane, and contains many macromolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites.

Cells can acquire specified function and carry out various tasks within the cell such as replication, DNA repair, protein synthesis, and motility. Cells are capable of specialization and mobility within the cell.

Most plant and animal cells are only visible under a light microscope, with dimensions between 1 and 100 micrometres. Electron microscopy gives a much higher resolution showing greatly detailed cell structure.

Most unicellular organisms are classed as microorganisms.

Cell biology is the study of cells, which were discovered by Robert Hooke in 1665, who named them for their resemblance to cells inhabited by Christian monks in a monastery.

With continual improvements made to microscopes over time, magnification technology became advanced enough to discover cells. This discovery is largely attributed to Robert Hooke, and began the scientific study of cells, known as cell biology.

This was shocking at the time as it was believed no one else had seen these. To further support his theory, Matthias Schleiden and Theodor Schwann both also studied cells of both animal and plants.

This put forth the idea that cells were not only fundamental to plants, but animals as well.

it has been estimated that the human body contains around 37 trillion (3.72×1013) cells, and more recent studies put this number at around 30 trillion (~36 trillion cells in the male, ~28 trillion in the female). The human brain accounts for around 80 billion of these cells.

provide numbers for most other human organs.

Prokaryotes are single-celled organisms, whereas eukaryotes can be either single-celled or multicellular.

Prokaryotic cells were the first form of life on Earth, characterized by having vital biological processes including cell signaling. They are simpler and smaller than eukaryotic cells, and lack a nucleus, and other membrane-bound organelles.

The nuclear region in the cytoplasm is called the nucleoid. Most prokaryotes are the smallest of all organisms ranging from 0.5 to 2.0 μm in diameter.

A prokaryotic cell has three regions:. Cell shape, also called cell morphology, has been hypothesized to form from the arrangement and movement of the cytoskeleton.

coli, and B. subtilis.

Some cell shapes that have been identified include rods, cocci and spirochaetes. Cocci are circular, bacilli are elongated rods, and spirochaetes are spiral in form.

Plants, animals, fungi, slime moulds, protozoa, and algae are all eukaryotic. These cells are about fifteen times wider than a typical prokaryote and can be as much as a thousand times greater in volume.

Most important among these is a cell nucleus, an organelle that houses the cell’s DNA. This nucleus gives the eukaryote its name, which means “true kernel (nucleus)”.

All cells, whether prokaryotic or eukaryotic, have a membrane that envelops the cell, regulates what moves in and out (selectively permeable), and maintains the electric potential of the cell. Inside the membrane, the cytoplasm takes up most of the cell’s volume.

There are also other kinds of biomolecules in cells. This article lists these primary cellular components, then briefly describes their function.

The cell membrane, or plasma membrane, is a selectively permeable biological membrane that surrounds the cytoplasm of a cell. In animals, the plasma membrane is the outer boundary of the cell, while in plants and prokaryotes it is usually covered by a cell wall.

Hence, the layer is called a phospholipid bilayer, or sometimes a fluid mosaic membrane. Embedded within this membrane is a macromolecular structure called the porosome the universal secretory portal in cells and a variety of protein molecules that act as channels and pumps that move different molecules into and out of the cell.

Cell surface membranes also contain receptor proteins that allow cells to detect external signaling molecules such as hormones.

anchors organelles in place. helps during endocytosis, the uptake of external materials by a cell, and cytokinesis, the separation of daughter cells after cell division.

The eukaryotic cytoskeleton is composed of microtubules, intermediate filaments and microfilaments. In the cytoskeleton of a neuron the intermediate filaments are known as neurofilaments.

The prokaryotic cytoskeleton is less well-studied but is involved in the maintenance of cell shape, polarity and cytokinesis. The subunit protein of microfilaments is a small, monomeric protein called actin.

Intermediate filaments are heteropolymers whose subunits vary among the cell types in different tissues. Some of the subunit proteins of intermediate filaments include vimentin, desmin, lamin (lamins A, B and C), keratin (multiple acidic and basic keratins), and neurofilament proteins (NF–L, NF–M).

Two different kinds of genetic material exist: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Cells use DNA for their long-term information storage.

RNA is used for information transport (e.g., mRNA) and enzymatic functions (e.g., ribosomal RNA). Transfer RNA (tRNA) molecules are used to add amino acids during protein translation.

Prokaryotic genetic material is organized in a simple circular bacterial chromosome in the nucleoid region of the cytoplasm. Eukaryotic genetic material is divided into different, linear molecules called chromosomes inside a discrete nucleus, usually with additional genetic material in some organelles like mitochondria and chloroplasts (see endosymbiotic theory).

A human cell has genetic material contained in the cell nucleus (the nuclear genome) and in the mitochondria (the mitochondrial genome). In humans, the nuclear genome is divided into 46 linear DNA molecules called chromosomes, including 22 homologous chromosome pairs and a pair of sex chromosomes.

Although the mitochondrial DNA is very small compared to nuclear chromosomes, it codes for 13 proteins involved in mitochondrial energy production and specific tRNAs.

This can be transient, if the DNA is not inserted into the cell’s genome, or stable, if it is. Certain viruses also insert their genetic material into the genome.

Organelles are parts of the cell that are adapted and/or specialized for carrying out one or more vital functions, analogous to the organs of the human body (such as the heart, lung, and kidney, with each organ performing a different function). Both eukaryotic and prokaryotic cells have organelles, but prokaryotic organelles are generally simpler and are not membrane-bound.