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The basic structure of a cell

The basic structure of a cell. Introduction. Cells are the basic units of organisms Cells were first observed by scientist under microscope Two basic types of cells Plant cells Animal cells. Plant cell. Made of cellulose which forms very thin fibres Strong and rigid. Cell wall.

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The basic structure of a cell

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  1. The basic structure of a cell

  2. Introduction • Cells are the basic units of organisms • Cells were first observed by scientist under microscope • Two basic types of cells • Plant cells • Animal cells

  3. Plant cell • Made of cellulose which forms very thin fibres • Strong and rigid • Cell wall

  4. Plant cell • Cell wall • Protect and support the enclosed substances (protoplasm) • Resist entry of excess water into the cell • Give shape to the cell

  5. Plant cell • Cell wall • Large spaces present between cellulose fibres • freely permeable

  6. Plant cell • Cell membrane • Lies immediately against the cell wall • Made of protein and lipid

  7. Plant cell • Cell membrane • Can control the movement of materials into and out of the cell • Selectively permeable

  8. Plant cell • Cytoplasm • Jelly-like substance enclosed by cell membrane • Provide a medium for chemical reactions to take place

  9. Plant cell • Chloroplasts • Contain the green pigment chlorophyll • To trap light energy to make food by photosynthesis • Contain starch grains (products of photosynthesis)

  10. Plant cell • Mitochondrion • Rod-shape • For respiration to take place • Active cells (sperms, liver cells) have more mitochondria

  11. Plant cell • Non-living granules • Starch granules • Oil droplets • Crystals of insoluble wastes

  12. Plant cell • Nucleus • Control the normal activities of the cell • Bound by a nuclear membrane • Contains thread-like chromosomes • Chromosomes carrygenes

  13. Plant cell • Vacuole • Surrounded by tonoplast • Contains cell sap • a solution of chemicals (sugars, proteins, mineral salts, wastes, pigments)

  14. Different kinds of plant cells

  15. cytoplasm Animal cell • No cell wall and chloroplast oil droplet glycogen granule nucleus • Stores glycogen granules and oil droplets in the cytoplasm mitochondrion cell membrane

  16. Different kinds of animal cells

  17. Similarities between plant cells and animal cells • Both have a cell membrane surrounding the cytoplasm • Both have a nucleus • Both contain mitochondria

  18. Differences between plant cells and animal cells Animal cells Plant cells Relatively smaller Relatively larger Irregular in size Regular in size No cell wall Cell wall present Vacuole small or absent Large central vacuole Glycogen granules as food store Starch granules as food store Nucleus at the centre Nucleus near cell wall

  19. Microscope • Instrument for observing small objects

  20. Different parts of a microscope Body tube Eyepiece Coarse adjustment Nose piece Objective Arm Fine adjustment Stage Clip Condenser Condenser adjustment Diaphragm Mirror

  21. The cell as the basic unit of life • Cell is the smallest unit of living organisms • Unicellular organisms are made of one cell only • The cells of multicellular organisms are specialized to perform different functions • e.g. mesophyll cells and root epidermal cells in plants

  22. Levels of organisation • Cells are group together and work as a whole to perform special functions

  23. Tissue • A group of similar cells to perform a particular job • Animals: epithelial tissue, muscular tissue • Plants: vascular tissue, mesophyll

  24. Organ • Different tissues group together to carry out specialized functions • Heart: consists of muscles, nervous tissue and blood vessels • Leaf: consists of epidermis, mesophyll and vascular tissue

  25. System • Several organs and tissues work together to carry out a particular set of functions in a co-ordinated way • Human: digestive, respiratory, excretory, circulatory and reproductive systems • Plant: root and shoot systems

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