CELLS STRUCTURE AND FUNCTION PDF DOWNLOAD!
Siyavula's open Life Sciences Grade 10 textbook, chapter 2 on Cells: The Basic Units Of Life covering Cell Structure And Function. A cell is a structural and functional unit of ist Robert Hook First studied the cell structure in the year using a self designed. Cell Structure and Function. Cell wall: It helps in protecting the plasma membrane and plays a vital role in supporting and protecting the cells. It is a thick outer layer made of cellulose. Cell membrane: It is a double layered, thin barrier, surrounding the cell to control the entry and exit of certain substances.
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They will be discussed later. Plant Cells The diagram below is a plant cell as may be seen using a light microscope. All the living matter of a plant cell is also called protoplasm.
Unlike the animal cell the plant cell also has a cell wall surrounding it. This is made of cellulose and is very rigid. It supports the plant cell.
The vacuole is a storage area for the plant cell. The vacuole contains cell sap. This is made of sugars, salts, and pigments. The chloroplasts contain chlorophyll.
This is where photosynthesis occurs within the cell.
Human Physiology - Cell structure and function
The Ultrastructure of Cells With the invention of the electron microscope a whole new world was open up to scientists. Most light microscopes will enlarge a specimen up to times X but the electron microscope enlarge the specimen ,X and higher!
Using cells structure and function microscopes scientists were able to discover parts of the cell never seen or known of before. The fine detail of a cell when seen by an electron microscope is called ultrstructure.
Cell Membrane Plasma Membrane Below cells structure and function a diagram of a part of the plasma membrane. Note that they are composed of phospholipid molecules and protein. The phosphate heads of each molecule is on the outside of the structure while the lipid tail of each are on the inside part of the membrane.
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The protein location varies along the membrane. Note that there are pores along the membrane.
This is where materials enter and leave the cell. The parts of the membrane move around constantly. That is cells structure and function the membrane is said to be fluid. Cytoskeleton Just as your body depends on your skeleton to maintain its shape and size, so a cell needs structures to maintain its shape and size In animal cells, which have no cell wall, an internal framework called the cytoskeleton maintains the shape of the cell, and helps the cell to move The cytoskeleton consists of two structures: They are made of actin, and are common in motile cells.
Structure and Function of the Cell
Microtubules have three functions: To maintain the shape of the cell To serve as tracks for organelles to move along within the cell They form the centriole This consists of two bundles of microtubules at right-angles to each other Each bundle contains 9 tubes in a very characteristic arrangement At the start of mitosis and meiosis, the centriole divides, and one half moves to each end of the cell, forming the spindle The spindle fibres are later shortened to pull the chromosomes apart Cilia and flagellae Cilia and Flagellae are structures that project from the cell, where they assist in movement Cilia sing.
Cells from different organisms have an even greater difference in structure Plant cells have three additional structures not found in animal cells structure and function Cellulose cell walls A Central Vacuole Cellulose cell wall One of the most important features of all plants is presence of a cellulose cell wall.
Fungi such as Mushrooms and Yeast also have cell walls, but these are made of chitin. The cell wall is freely permeable porousand so has no direct effect on the movement of molecules into or out of the cell.
The rigidity of their cell walls helps both to support and protect the plant. Plant cell walls are of two types: Primary cellulose cell wall - While a plant cell is being formed, a middle lamella made of pectin, is formed and the cellulose cell wall develops between the middle lamella and cells structure and function cell membrane.