CELL STRUCTURE &

1. CELL STRUCTURE & CELL ORGANIZATION

3. Cell structure & function • Plants and animal are built of cells. • The cell is basic unit of structure and function in an organism. • Our body is made up at least 1012 cells.

4. The German scientists put forth the ‘Cell Theory’ which state that : • all organisms are made up of one or more cells. • The cells is the basic unit of life. • All cells arise from pre-existing cells.

5. Cells consists of three main parts: • plasma membrane • Cytoplasm • nucleus

6. PLASMA MEMBRANE • Serves as boundary between the cell and its environment • Act as selective barrier, controlling the passage of materials in and out of the cell • Help to recognize the other cells

7. CYTOPLASM • A jelly like medium • Many biochemical reactions take place • Contains substance such as enzyme, oil droplets, glycogen granules(in animal cells only), and starch grains(in plants cell only) • Stores a variety of organelles. Most of the function of the cytoplasm are the function of organelles in it.

8. CYTOPLASM • A jelly like medium • Many biochemical reactions take place • Contains substance such as enzyme, oil droplets, glycogen granules(in animal cells only), and starch grains(in plants cell only) • Stores a variety of organelles. Most of the function of the cytoplasm are the function of organelles in it.

9. NUCLEUS • Contain the genetic materialof a cell in the form of chromosome. • Act as control centre for the activities of a cells. • Produces ribosome and ribonucleic acid(RNA). • Play an essential role in cell division.

11. CELL WALL • Allow the movement of water through and along the cell wall • Gives support to the cell and the plant as the whole by providing mechanical strength • Determines the overall shape of the cell • Prevents plant cell from bursting when water enter it by osmosis

12. ROUGH END OPLASMIC RETICULUM • Involves in the synthesis of proteins, especially the extra cellular enzymes. • Provide a pathway for the transport of the materials in the cell(intracellular transport system). • Provides the large surface area for the chemical reactions

13. SMOOTH END OPLASMIC RETICULUM • Produce lipids, for example steroids and other non protein substance

14. MITOCHON D R ION • Membrane bound organelles • Provide the energy a cell needs to move, divide, produce secretary products • They are the power center of the cell • May have different shapes depending on the cell part

15. GOLGI APPARATUS • Collects, packs and distribute molecule synthesized in the cell. • Produced glycoprotein, polysaccharides, and secretory enzymes. • Forms lysosomes. • Transport and stores lipid

16. LYSOSOMES • D igest the cell which the cell consumes • D estroy unwanted or worn out organelles • Completely breakdown the cells after it death • Release enzyme outside the cell to digest external material

17. RIBOSOMES • Sites for protein synthesis • Packets of RNA and protein • Each ribosomes comprise of 2 parts, a large subunit and small subunit

18. CHLOROLPLAST • Specialized organelles found in higher plant cells. • Sites for photosynthesis • Contain cell chlorophyll responsible for a plants green colour • Have a double outer membrane • Within a stroma are the other membrane structure called thylakoids.

19. CENTRIOLE • Form the spindle during cell division of animals cell • Gives rises to cilium and flagellum

20. VACOULE • Stores sugar and amino acids in its sap • Stores organic wastes in vacuoles of leaf cells • Support herbaceous plants by turgor pressure

21. Similarities of animal and plant cells • Both animal cell and plant cell have • plasma membranes • Cytoplasm • Mitochondria • Ribosome • Endoplasmic reticulum • Golgi apparatus • Nuclei bounded by nuclear membrane

22. Differences of plant and animal cell

23. Relationship between densities of certain organelles with the function of specific cells 1. Cells that require the most energy contain generating mitochondria. 2. The cell of the brain,liver, kidney tubule, skeletal muscle have thounsands of mitochondria in each cell while cells of skin, which do not require much energy, have only a few hundred mitochondria. 3. The eggs cell has around 1000 mitochondria. 4. The sperm cell has large numbers of mitochondria in its middle piece. 5. In flowering plants, the chloroplast are especially dense in palisemesophyll cells. Each cell has up to 100 chloroplasts.

24. Cell Organisation • Organisms can be categorised as unicellular or multicellular. • Unicellular organisms are organisms with just one cell. For example Amoeba and Paramecium. • Mutlicellular organisms are made up of more than one cell.

25. Cell organisation in formation of tissues,organs and systems in multicellular organisms • There are many types of cells. • The study of cells is knows as cytology. Cell Tissue Level of organisation Organ Tissue

26. Cell – the smallests unit of life capable of carrying out all the functions of living things. • Tissue- a group of cells of the same type that perform a specific function in organism. • Organ- Several types of tissues that carry out a particular function. • Organ system - several organ working together to perform a function.

27. Examples of human cells and their functions

28. Some of the plant cells and their functions

29. Tissue • The study of tissue is k nown as histology. • In human and animals, there are four basic types of tissues.

30. There are three major plant tissues, epidermis, ground tissue and vascular tissue.

31. Organ • Organ consists of se v eral types of tissues and it is specialied to perform a specific function. • Example of human organ: hearth which consists of muscle tissue, epitheal tissue, connecti v e tissue and ner v ous tissue. • Others example of organs include skin, stomach, kidney, intestines, liver and blood vessels.

32. Organ system. • Consists of group of organs which carry out major functions such as respiratory, nutrition, excretion and others.

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