Cells

9. Cells

10. Objectives • Label the different parts of the cell • Describe the functions of the different parts of the cell • Compare a typical animal cell to a typical plant cell • Explain what is meant by ‘tissues’ and ‘organs’

11. Introduction • A cell is the basic unit of ALL living things/organisms • It is the smallest part of a living thing that is alive and is only visible under the microscope • As such, they are the building blocks of life

12. Cells can take in nutrients and convert them into energy they need to stay alive • They can also carry out specialised functions Red blood cells – carry oxygen Muscle cells – contract to allow movement

13. Living things can be classified as: • Unicellular (only 1 cell) e.g., bacteria 2) Multicellular (many cells) e.g., human, plants

14. There are many kinds of cells with different shapes and sizes • But they may share some common features • Our focus: • Plant cell • Animal cell

15. Animal cells • Basic structure of a typical animal cell: • Cell membrane • Cytoplasm • Nucleus • Vacuole • Mitochondria • Ribosomes • Endoplasmic reticulum - Smooth and rough ORGANELLES

16. An organelle is a specialized subunitwithin a cell that has a specific function, and is usually separately enclosed

17. Cell membrane • A thin layer surrounding the cell • Semi-permeable – it only allows SOME substances to pass through but not others • It functions to control the movement of substances in and out of a cell

18. Cytoplasm • Jelly-like substance that fills the cell • Contains water and many other substances • It is where many chemical reactions take place e.g., converting nutrients to energy

19. Nucleus • It controls the activities of a cell • Usually found in the centre of an animal cell • Contains hereditary materials called chromosomes • Chromosomes carry genes which are passed from parents to their children

20. Vacuoles • Membrane-enclosed fluid which stores food or nutrients needed by the cells • Animal cells have MANYvacuoles

21. Mitochondria • Mitochondria are the cell's power producers • They convert nutrients into energy that is usable by the cell

22. Ribosomes • Can be found in the cytoplasm and on the endoplasmic reticulum • Function in protein production ribosomes

23. Endoplasmic reticulum • A network tubules and sacs that serves as the cell’s transport system • Can also function in storage and production

24. Has ribosomes on its outer surface • Mainly involved in protein production Rough endoplasmic reticulum • No ribosomes on outer surface • Mainly involved in lipid (fat) production Smooth endoplasmic reticulum

25. Drawing an animal cell

26. Plant cells • Basic structure of a typical plant cell: • Cell membrane • Cytoplasm • Nucleus • Vacuole • Mitochondria • Chloroplasts • Cell wall • Endoplasmic reticulum Organelle found only in plant cells

27. Cell membrane • Just like animal cells, plant cells also have a semi-permeable layer around them • Similarly, it controls the movement of substances in and out of the cell

28. Cytoplasm • This is the same kind of jelly-like substance as that found in animal cells • Many chemical reactions would take place here

29. Nucleus • Also like in animal cells, it controls the activities of the cell • Because of a larger vacuole, it is pushed to one side of cell rather than being found in the middle of the cell (e.g., in animal cells)

30. Vacuole • It is often a single, large space containing a liquid called cell sap (large central vacuole) • It contains water and dissolved substance such as sugar and salt

31. Mitochondria • Same as in animal cells • These are power sources that fuel cellular activities

32. Ribosomes • Play a role in producing proteins • Same as in animal cells • Can be found in cytoplasm or surface of endoplasmic reticulum

33. Endoplasmic reticulum Smooth endoplasmic reticulum Function in protein synthesis Rough endoplasmic reticulum Function in lipid synthesis

34. Cell wall • A layer (thicker than cell membrane) surrounding the cell • Made of a tough substance called cellulose • It supports the cell and gives it a regular shape • Prevents the cell from bursting when water enters it excessively

35. Chloroplasts • Small disc-like structures found in plant cells • They contain a green substance called chlorophyll which absorbs light energy to make food during photosynthesis

36. Drawing a plant cell

37. Differences between plant cells and animal cells

38. Similarities between plant and animal cells

39. Division of labour– cellular level • In multicellular organisms, different cells perform different functions • Division of labour – division of work among cells in an organism • They are specialised in their functions and have special features to allow them to do so • This designation of different functions allows efficient functioning in multicellular organisms

40. Example of specialised cells in animals RBCs have no nucleus and carry a protein called hemoglobin to transport oxygen

41. Example of specialised cells in plants • Xylem vessels are non-living cells that form tubes for transporting water and mineral salts • Root hair cells have a tubular extension to increase the surface area for water absorption • Palisade cells have many chloroplasts to capture the maximum amount of sunlight for photosynthesis

42. Levels of organisation of cells From cells to tissues (When cells of the same type work together to do the same job, they make up a tissue)

43. From tissues to organ (When different tissues work together to do a particular job, they make up an organ)

44. From tissues to system (When different organs work together to do a particular job, they make up a system)