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Cell Structure and Organisation


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Cell Structure and Organisation

  1. 1. Eye cell Egg cell Cheek cell Nerve cell Red Blood cell White Blood cell Sperm cell Hair cell
  2. 2. Cell Structure and Organisation
  3. 3. Objectives <ul><li>At the end of the lesson, you will be able to </li></ul><ul><li>identify organelles of typical plant and animal cells from diagrams, photomicrographs and as seen under the light microscope using prepared slides and fresh material treated with an appropriate temporary staining technique </li></ul><ul><li>identify the following organelles from diagrams and electronmicrographs: mitochondria, ribosomes, endoplasmic reticulum, golgi body </li></ul><ul><li>state the functions of the organelles that are taught </li></ul><ul><li>compare the structure of typical animal and plant cells </li></ul><ul><li>state , in simple terms, the relationship between cell function and cell structure for the following: </li></ul><ul><ul><li>absorption – root hair cells </li></ul></ul><ul><ul><li>conduction and support – xylem vessels </li></ul></ul><ul><ul><li>transport of oxygen – red blood cells (RBCs) </li></ul></ul>
  4. 4. <ul><li>What are cells? </li></ul>Recall What are the parts of the cells that you have learnt? Are all the cells the same? How do cells work together?
  5. 5. <ul><li>Building blocks of life </li></ul><ul><li>Many chemical reactions occur within cell to keep the cell alive </li></ul><ul><li>Very small, need microscope to be seen </li></ul>What are cells? Light microscope Magnify up to 1000x Electron microscope Magnify up to 200,000x
  6. 6. Cross-section of an animal cell golgi body* rough endoplasmic reticulum* vacuole cell membrane ribosome* cytoplasm nucleus *can only be seen under an electron microscope nucleolus smooth endoplasmic reticulum* mitochondrion*
  7. 7. Parts of an animal cell Please refer to TB Pg 17 – 23 for more information. fluid-filled space enclosed by a membrane; contains water and food substances ; present as many small vacuoles Vacuole contains genetic information (chromatin) , or instructions for making molecules (DNA) and controls all cell activities. nucleus breaks down glucose to release energy (during cellular respiration). Mitochondrion (singular) Mitochondria (pl.) composed mostly of water, where most chemical reactions take place cytoplasm surrounds the cell as a partially permeable membrane; controls the entry and exit of substances cell surface membrane Functions Name
  8. 8. Parts of an animal cell Please refer to TB Pg 17 – 23 for more information. <ul><li>either attached to RER and make proteins that are transported out of the cell </li></ul><ul><li>or lie freely in the cytoplasm and make proteins that are used by the cell . </li></ul>ribosomes stores and modifies substances made by the ribosomes and package these substances in vesicles to secrete out of the cell. golgi bodies/golgi apparatus transports proteins made by ribosomes that are attached to the RER to the golgi apparatus. rough endoplasmic reticulum (RER) <ul><li>synthesizes substances, such as fats and sex hormones </li></ul><ul><li>breaks down harmful substances (detoxification). </li></ul>smooth endoplasmic reticulum (SER) a network of membranes within cytoplasm; consists of SER and RER Endoplasmic Reticulum (ER) Functions Name
  9. 9. cytoplasm Rough endoplasmic reticulum (RER) (with bound ribosomes to make proteins for export) free ribosomes (to make proteins for own use) Smooth endoplasmic reticulum (SER)
  10. 10. Golgi Body and ER
  11. 11. Quick Check - Knowledge <ul><li>Name the structures in the cell that </li></ul>2. Name the cell organelle in each electronmicrograph. cell surface membrane nucleus mitochondrion golgi body mitochondrion golgi body stores and modifies substances by the ER for secretion out of the cell (d) releases energy during respiration (c) contains hereditary information (b) controls substances entering or leaving the cell (a)
  12. 12. Cross-section of a plant Cell
  13. 13. Examples of plant cells chloroplasts guard cells mesophyll cells in leaf
  14. 15. Parts of a plant cell <ul><li>Contains all the parts of an animal cells (refer to slide 4) except for centrioles </li></ul><ul><li>Functions of these parts are the same as the animal (refer to slides 5 and 6) </li></ul><ul><li>Addition of other parts in a plant cell </li></ul>present as one large central vacuole in plant cell (especially mature plant cells; contains cell sap which contains dissolved substances such as water, sugar, amino acids and mineral salts vacuole contains green pigment called chlorophyll (absorbs light energy); region where photosynthesis takes place chloroplast <ul><li>tough layer due to the presence of cellulose </li></ul><ul><li>gives the cell its shape </li></ul><ul><li>protects the cell </li></ul>cell wall Functions Parts
  15. 16. Plant Cell vs Animal Cell Cell wall is present. Cell wall is absent. Chloroplasts are present. Chloroplast are absent. Centrioles are absent. Centrioles are present. A large central vacuole Many small vacuoles Animal Cell Plant Cell
  16. 17. <ul><li>1. cell membrane, small vacuoles, large central vacuole, cytoplasm, nucleus, chloroplasts, mitochondria, ER, Golgi apparatus, ribosomes </li></ul><ul><li>Which of the listed structures above is/are: </li></ul><ul><li>(a) present in both plant and animal cells </li></ul><ul><li>(b) present in animal cells only </li></ul><ul><li>(c) present in plant cells only </li></ul>Quick Check - Knowledge cell membrane, cytoplasm, nucleus, mitochondria, ER, Golgi apparatus, ribosomes small vacuoles large central vacuole, chloroplasts
  17. 18. <ul><li>2. John made the following observations about two cells he viewed under the microscope: </li></ul><ul><li>Identify which cell is a plant cell and which cell is an animal cell. </li></ul>Quick Check – Knowledge with Understanding Cell A: Plant Cell B: Animal Several membrane-like organelles scattered all over Several membrane-like organelles scattered all over Thin outer covering surrounding the cells Thick outer covering surrounding the cells Small fluid-filled cavities Large sap-filled portion A dark and dense structure near the middle of the cell A dark and dense structure at the side of the cell Cell B Cell A
  18. 19. GROUP WORK (10 minutes) <ul><li>In groups of 4, </li></ul><ul><li>Choose 2 objects that serve the same general function </li></ul><ul><li>However, one object is able to function in a more specialised way. </li></ul><ul><li>On the given paper, show the differences between the two objects in how one is equipped for specialisation </li></ul><ul><li>Present your answer at the end of discussion </li></ul>
  19. 20. Example <ul><li>Cars need to be modified to carry out specialised functions </li></ul><ul><ul><li>Toyata Corolla – family car </li></ul></ul><ul><ul><li>Porsche – sports car </li></ul></ul>
  20. 21. Modification of Cells <ul><li>Not every cell in a multi-cellular organism is the same. </li></ul><ul><li>Cells need to be modified to carry out specialized functions. </li></ul>neurone
  21. 22. Modification of Cells <ul><li>Examples of modification of cells </li></ul><ul><li>Red blood cell </li></ul><ul><li>Root hair cell </li></ul><ul><li>Xylem vessel </li></ul>
  22. 23. Red Blood Cell cell membrane cytoplasm filled with haemoglobin Front View <ul><li>Function: transport oxygen from lungs to all parts of the body </li></ul><ul><li>Modifications: </li></ul><ul><li>haemoglobin: a red pigment that binds to oxygen </li></ul><ul><li>biconcave shape: increases surface area to volume ratio for faster diffusion of oxygen </li></ul><ul><li>flexible cell membrane: allows red blood cell to bend to squeeze through narrow capillary </li></ul>centre is dented
  23. 24. Root Hair Cell root hairs
  24. 25. Root Hair Cell cell wall cell membrane cytoplasm vacuole nucleus Function: absorbs water and mineral salts from the surrounding <ul><li>Modifications: </li></ul><ul><li>elongated: increases surface area to volume ratio for faster absorption of water and mineral salts </li></ul><ul><li>presence of sap vacuole: lowers its water potential so that water can be absorbed by osmosis </li></ul><ul><li>large vacuole: stores as much water as possible </li></ul>
  25. 26. Xylem Vessel lignin
  26. 27. Xylem Vessel no cross wall, hollow lumen thick, lignified wall water and mineral salts travel upwards Longitudinal section Cross section <ul><li>Functions: (1) supports the plant, (2) transports water and mineral salts from the roots to the leaves </li></ul><ul><li>Modifications: </li></ul><ul><li>thick, lignified wall: prevents the collapse of xylem vessel </li></ul><ul><li>hollow lumen: allows easy flow of water and mineral salts up the xylem vessel without obstruction </li></ul><ul><li>narrow lumen: allows fast movement of water by capillary action </li></ul>
  27. 28. Organization of Cells cells tissues organs systems A group of similar or different cells work together for a specific function. E.g cardiac muscle Different tissues work together for a specific function. E.g Heart Different organs work together to support the whole system. E.g. circulatory system The basic unit of living things. E.g. muscle cell organism Different systems work together to support the whole organism. E.g. Human
  28. 29. Are all organisms made of many cells? amoeba – unicellular organism plants and animals – multicellular organisms