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anonymous

  • one year ago

A Plant and Animal Cells Tutorial

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  1. anonymous
    • one year ago
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    \(\Large\sf\color{orange}{1.~Cell~Membrane}\) The cell membrane, also called the plasma membrane, surrounds the cell. The membrane serves as a selective barrier for the cell, meaning that it allows some things to pass into or out of the cell but not others. For example, oxygen and nutrients pass into the cell through the membrane, and waste products pass out of the cell. Each organelle inside a eukaryotic cell is also surrounded by a membrane. These membranes serve as a selective barrier for the organelles and determine what can enter or leave. Each of these membranes, like the cell membrane, is made up of lipids and contains a variety of proteins. \(\Large\sf\color{orange}{2.~Nucleus}\) The cell’s nucleus is one of the easiest organelles to identify when looking at a eukaryotic cell under a microscope. It is large, usually close to the center, and it contains a tangled mass of chromatin that appears darker than its surroundings. The nucleus contains most of the cell’s genetic information, its DNA, which orchestrates the structure and function of the cell. Inside the nucleus, the cell’s DNA and some proteins are packed together into chromosomes. When the cell is not in the process of dividing, the chromosomes are stringy and entangled, which makes it too difficult to identify them as individual structures. The tangled mass of chromosomes is collectively called chromatin. The most visible structure within the nucleus is the nucleolus, which is important for the synthesis of ribosomes. Some cells only have one nucleolus inside the nucleus, while others have two or more. This can depend on the species as well as the stage in the cell’s reproductive cycle. \(\Large\sf\color{orange}{3.~Cytoplasm~and~Cytoskeleton}\) Cytoplasm is the thick fluid that fills up a cell and surrounds all of the organelles. It is a mixture of water and dissolved salts, ions, and organic molecules. Many of these substances are involved in reactions that occur within the cytoplasm, while others are transported to various organelles to be used. In the early days of electron microscopes, scientists thought the organelles were just floating in the gel-like cytoplasm. With improved microscope technology, they discovered a network of fibers throughout the cell, which they called the cytoskeleton. The functions of the cytoskeleton are comparable to the bones and muscles of our bodies. Just as our skeleton forms the shape of our bodies and our muscles direct our movement, the fibers of the cytoskeleton give the cell shape, anchor many of the organelles in place, and direct the movement of organelles. \(\Large\sf\color{orange}{4.~Ribosomes}\) Ribosomes are the locations for protein synthesis within a cell. They are generally considered to be the cell’s smallest organelles, and they generally look like small dots through a microscope. These small organelles are made in the nucleolus, and can be found in two main locations within a cell. Free ribosomes are found separated within the cell’s cytoplasm, while bound ribosomes are found attached to another organelle called the rough endoplasmic reticulum. Ribosomes are made up of RNA and protein molecules. Although they appear like tiny dots under a microscope, ribosomes consist of two separate parts. Long protein chains are assembled between the two parts of the ribosome. Whether a ribosome is connected or free, its job is to synthesize proteins. Genetic information is copied from the cell’s DNA in the nucleus and carried by messenger RNA to the ribosomes. This is where the construction of large protein molecules occurs. These proteins are then released to the areas that require them. Cells that need to produce a lot of protein, like human liver cells, have a greater number of ribosomes than other cells. Free ribosomes tend to make proteins to be used within the cytoplasm. Bound ribosomes generally make proteins that are to be used for building membranes or exported from the cell for use in other parts of the body. \(\Large\sf\color{orange}{5.~Endoplasmic~Reticulum}\) The endoplasmic reticulum (ER) is a maze of membranes so long that it accounts for more than half of the total membrane found in the cell. It is divided into two distinct sections of ER that differ in structure and function. \(\Large\sf\color{orange}{5.1:~Rough~ER}\) The rough endoplasmic reticulum appears rough because its surface is covered by small ribosomes. These ribosomes synthesize proteins, and the membrane of the rough ER keeps those proteins separate from the rest of the cell. In addition to making and storing proteins, the rough ER makes its own proteins and phospholipids to add to its membrane. This is important because portions of the ER’s membrane are pinched off to form sealed sacs called transport vesicles. These vesicles carry the newly made proteins from the rough ER to the cell’s Golgi apparatus. \(\Large\sf\color{orange}{5.2:~Smooth~ER}\) The smooth endoplasmic reticulum does not have any ribosomes on its membrane. Its specific functions vary depending on the specializations of the cell in which it is located. The smooth ER participates in various metabolic processes, including the construction of lipids, the deconstruction of carbohydrates, and the detoxification of substances that may otherwise be harmful to the cell. \(\Large\sf\color{orange}{6.~Golgi~Apparatus}\) The Golgi apparatus is made up of stacks of membrane sacs. Transport vesicles, carrying proteins from the endoplasmic reticulum, enter the Golgi apparatus to be modified and stored. Eventually, these proteins are sent on to their final destinations inside or outside of the cell. Vesicles that bud off of the endoplasmic reticulum attach to the Golgi apparatus’s membrane. The membrane and contents of the transport vesicle become incorporated into the Golgi apparatus, where the protein contents are then modified and stored. At the other end of the Golgi apparatus, new vesicles will form and be pinched off to carry materials to other sites in the cell as needed. \(\Large\sf\color{orange}{7.~Lysosomes}\) A lysosome is a membrane sac that contains enzymes. These enzymes are used to digest or break down large molecules into smaller molecules to be used by the cell. Lysosomes and the enzymes they contain are both made in the rough endoplasmic reticulum and then transferred to the Golgi apparatus for further processing. A cell contains a variety of lysosomes, each containing different enzymes that break down a specific type of macromolecule. A lysosome provides an acidic environment where enzymes can digest large macromolecules without disturbing the functions of other molecules important to the cell. \(\Large\sf\color{orange}{8.~Vacuoles}\) Vacuoles are membrane-enclosed sacs that serve a variety of storage functions. Food vacuoles store food and nutrients that pass through the cell membrane, while water vacuoles store water, minerals, and ions. Some single-celled organisms that live in water have contractile vacuoles that act as small pumps to remove some of the water from the cell. Vacuoles and vesicles are both membrane-enclosed sacs, but vacuoles are usually larger. In a plant cell, there is often one large central vacuole that takes up around 80% of the cell’s volume. Because many plant cells do not have specialized lysosomes, the central vacuole often serves as a storage area for enzymes as well. \(\Large\sf\color{orange}{9.~Mitochondria}\) A mitochondrion is enclosed in a layer of two membranes. The inner layer has folds in the membrane, called cristae, while the outer layer is smooth. This structure suits its functions well because the folds in the inner membrane provide additional surface area on which important reactions occur, allowing each mitochondrion to do more work. Mitochondria are often called the powerhouse of the cell. They are organelles that act like the cell’s digestive system, taking in nutrients and breaking them down. The chemical reactions that break down the nutrients release energy to power the cell. One of the most important reactions that occur in the mitochondria is called cellular respiration, a process that uses molecules like glucose to release forms of energy that can be used by the cell. Nearly all eukaryotic cells contain mitochondria. Some have one single mitochondrion, but more often, cells have hundreds or even thousands of mitochondria. The number of mitochondria in a cell relate to its metabolic activity, or the amount of energy it needs. For example, muscle cells will probably have more mitochondria than nerve cells because muscle cells need more energy for movement. If a cell is not getting enough energy to survive, its mitochondria can reproduce and form more mitochondria to digest nutrients for the cell. \(\Large\sf\color{orange}{10.~Cell~Wall}\) A cell wall is one component of plant cells that is not found in animal cells. A cell wall surrounds the cell membrane and provides an additional layer of protection for plant cells. Due to its makeup, a mixture of cellulose, polysaccharides, and imbedded proteins, the cell wall is able to help maintain the shape of the cell and prevent excess intake or loss of water. \(\Large\sf\color{orange}{11.~Chloroplasts}\) Chloroplasts are found in plant cells but not in animal cells. They are green in color because they contain the green pigment chlorophyll. Chloroplasts are enclosed by a double membrane and contain a system of membranes arranged in stacks of flattened sacs. This provides a lot of surface area on which reactions can occur. Chloroplasts are important because they convert energy from sunlight into chemical energy the cell can use. This process is called photosynthesis. Chloroplasts use energy from the sun to make glucose, which is an important energy source for plants and animals.

  2. anonymous
    • one year ago
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    As you have seen, each organelle has a specific job to do that ensures the proper functioning of the cell. When part of a multicellular organism, eukaryotic cells can also have specialized jobs. Liver cells serve a different function than heart cells, and that difference is evident when you examine the structures of both under a microscope. Yet, both of these cells are important to the survival of our bodies as a whole. Just as the organelles inside a eukaryotic cell work together to keep the cell functioning properly, the different types of specialized eukaryotic cells within a multicelled organism work together to keep the organism alive.

  3. anonymous
    • one year ago
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    Picture of Plant Cell:

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  4. anonymous
    • one year ago
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    Picture of Animal Cell:

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  5. anonymous
    • one year ago
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    \(\color{blue}{\href{http:///www.enchantedlearning.com/subjects/plants/cell/}{Please~note~that~I~do~not~own~the~picture(s)~provided.}}\)

  6. anonymous
    • one year ago
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    \(\Large\frak\color{pink}{End~of~Tutorial}\) Any questions, comments, or concerns?

  7. Abhisar
    • one year ago
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    That's nice and clean ! Just wanted to bring something into notice, not all eukaryotic organelles are membrane bound. For example, ribosomes

  8. pooja195
    • one year ago
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    I'm impressed :D good job! ^_^

  9. anonymous
    • one year ago
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    Very good Job. :)

  10. anonymous
    • one year ago
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    @Abhisar In all due respect, please refer to Ribosomes #4: "Free ribosomes are found separated within the cell’s cytoplasm…"

  11. rvc
    • one year ago
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    :)

  12. nincompoop
    • one year ago
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    An organ's function or functions are not simply due to the structure of the aggregate cells it is made of (tissues), it is also due to the organelles that the cells are mostly made of.

  13. anonymous
    • one year ago
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    Thank you for that addition :)

  14. nincompoop
    • one year ago
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    It is critical to note that this tutorial is just an overview and does not provide a complete depiction of the functions and concerted functions these organelles are involved in.

  15. nincompoop
    • one year ago
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    The attachment says "advanced levels" but it is something 6th graders start doing in the lab.

  16. anonymous
    • one year ago
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    This tutorial is mainly targeted for the 8th-9th grade basic biology students.

  17. anonymous
    • one year ago
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    Some do not consider ribosomes true organelles, others do. This is unfortunate because it means that different books and schools will treat and teach them quite differently. Also, I would point out that in filamentous fungi, it is a real pain to find the nucleus, unless you stain it. This is not the case in all Eukaryotes.

  18. anonymous
    • one year ago
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    Interesting! @mrdoldum

  19. nincompoop
    • one year ago
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    I treat it as an organelle

  20. nincompoop
    • one year ago
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    for every rule (membrane-bound) there is always an exception and this one is one of them

  21. SyedMohammed98
    • one year ago
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    GOOD J☻B :)

  22. anonymous
    • one year ago
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    You didnt make this...you copied it and pasted it from Florida Virtual School Website Biology Segment 1.

  23. abb0t
    • one year ago
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    I agree. Plus, this video is better: https://www.youtube.com/watch?v=1Z9pqST72is

  24. anonymous
    • one year ago
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    Eh, not a big deal to me. This is a "tutorial" post, it would be one thing if it was for answers not general information w/o question. However, it would be better to post the source so others can find it and use the resources on the source page as well.

  25. anonymous
    • one year ago
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    @kingalex123 Well, in the USA copyright law allows for the "fair use" of copyrighted material in certain instances; educational use is one of those. Yes, it would have been better if she gave us the source, but not a big deal to me. Now if it was for homework or similar, I'd have a problem with it.

  26. anonymous
    • one year ago
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    @kingalex123 @mrdoldum I appreciate the ongoing conversation you have there, but yes, this is just for educational use only, so it is under the fair use of copyrighted material, if it really is.

  27. sammixboo
    • one month ago
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    Good job!

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