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IGCSE Unit 1 Cell
- A cell is the basic unit of structure and function in organisms, and all organisms are unicellular or multicellular. - Key structures of the animal cell include the cell membrane, nucleus, cytoplasm, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, and centrioles. The cell membrane regulates what enters and exits the cell, the nucleus houses genetic material, and mitochondria generate energy. - Plant cells also contain a cell wall, chloroplasts, and a central vacuole. The cell wall provides structure and support, chloroplasts facilitate photosynthesis, and the vacuole stores water and nutrients.
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IGCSE Unit 1 Cell
- 1. Cell B M SubramanyaSwamy M.Sc. B.Ed. CIE Co ordinator & Examination Officer Kanaan Global School Jakarta Indonesia [email protected]
- 2. Introduction • A cellis the basic unit of structure and function in an organism • All organisms are unicellular or multicellular • It is a smallest living unit showing all the characteristic of life and performing all the vital functions
- 3.
- 4. Structure Function Cell MembraneAlso called plasma membrane A thin delicate layer made of layers of proteins and fats Completely surrounds and holds in the constituents of the cell High surface area of the cell provides for absorption of nutrients and the disposal of wastes Differentially permeable controlling the transport of materials in and out of the cell Allow certain small substances like glucose water and oxygen to enter the cell Prevent larger molecules like protein and starch from leaving the cell
- 5. Nucleus Most prominentstructure of the cell Usually spherical in shape Found near the centre of the animal cell Bound by two membranes forming the nuclear envelop Isolates the genetic material from the rest of cell Nuclear pores are scattered over the surface of this envelop Found within the nucleus is one or more small spherical structure called the nucleolus which is not bound by a membrane Nucleoplasm is the cytoplasm like material that fills up the nucleus .it contains chromatin which is made up of DNA Involved in cell division Controls all cellular activity Houses the organisms genetic material Nuclear pores act as channels Permitting certain molecules to enter or leave the nucleus
- 6. Structure Function Cytoplasm Jellylike substance Fills up the cell Suspension of various organelles It is here that metabolisms takes place
- 7. Organelles Structure Functions Vacuoles Sacsfilled with cell sap a watery solution of sugars salts and pigments Some function during digestion eliminating excess water entrapping food particles or for discharging wastes
- 8. Structure Function Mitochondria Rodshaped organelles Structure with the inner folded membranes Permanent structure in the cell Power house of the cell Site for aerobic respiration which generates energy for all the cellular activities Inner folds carry respiratory enzymes which help to control respiration and the release of energy from glucose molecules in the cel Involved in chemical energy conversion during metaboli activities of the cell
- 9. Ribosomes • Translate thegenetic code into proteins. • Found attached to the Rough endoplasmic reticulum or free in the cytoplasm. • 60% RNA and 40% protein.
- 10. Rough Endoplasmic Reticulum •Network of continuous sacs, studded with ribosome's. • Manufactures, processes, and transports proteins for export from cell. • Continuous with nuclear envelope.
- 11. Golgi Apparatus • Modifiesproteins and lipids made by the ER and prepares them for export from the cell. • Encloses digestive enzymes into membranes to form lysosomes.
- 12. Lysosomes • Single membrane boundstructure. • Contains digestive enzymes that break down cellular waste and debris and nutrients for use by the cell.
- 13. Centrioles • Found onlyin animal cells. • Self-replicating • Made of bundles of microtubules. • Help in organizing cell division.
- 14. Structure Function Protoplasm Combinationof all the living parts of the cell Cells with protoplasm is regarded as living
- 16. Starch grains Structure Function Insolublecarbohydrates Occurs as very small grains Food source for plants
- 17. Cell wall Structure Function Rigidwall made up of a layer of cellulose Provides support and shape to the individuals
- 18. vacuole Structure function Large compartments Knownas a sap vacuole Filled with a fluid called cell sap Membrane that surrounds the vacuole called a Tonoplast Plays a role in osmoregulation Maintaining the shape of the cell
- 19. Chloroplast Structure Function Collection oforganelles known as plastids Plastids that store chlorophyll are known as chloroplast Characteristically green Absorption of sunlight Required to carry out photosynthesis
- 20. Compare and contrastplant and animal cells Structures Plant Animal Cell wall Rigid cell wall made of cellulose. It determines the size and shape of the cell. It also helps to support and strengthen the plant ----------------------- -------------
- 21. Structures Plants Animals Starchgrains Stores food as starch Can be found in plastids Excess carbohydrate is stored as glycogen granules
- 22. Sap vacuole Largeand centrally located It is usually filled with cell sap Small in size There may be some food vacuole or contractile vacuoles present
- 23. Tonoplast This isthe membrane that surrounds the sap vacuole formed by a layer of cytoplasm _______________________ ______________________ Chloroplast Found in green leaves actually it gives the leaf the characteristic green color It contains chlorophyll to trap light energy for photosynthesis ----------------------------------------- ----------------------------------------- ----------------------------------------- ----------------------------------------- --------------------------
- 24. Function of thecell membrane • The cell membrane is a thin layer of proteins and fats around the cell • It surrounds the living cells • Separates one cell from another adjacent cell • Controls and regulates the passage of substances in and out of the cells • Control the exchange rate of substances in order to maintain normal conditions inside the cell
- 26. Prokaryotic Cells • Believedto be the first cells to evolve. • Lack a membrane bound nucleus and organelles. • Genetic material is naked in the cytoplasm • Ribosome are only organelle.