JYSS Cells 2013


Published on

  • Be the first to comment

JYSS Cells 2013

  1. 1. Chapter 2CELL Structure andorganisation 1
  2. 2. Learning OutcomesAt the end of the lesson, you should be ableto: Identify chloroplasts, cell membrane, cell wall, cytoplasm, cell vacuoles, nucleus, mitochondria, ribosomes Identify endoplasmic reticulum and Golgi apparatus (Pure) State the functions of the organelles identified above Compare the structure of typical animal and plant cells
  3. 3. Learning Outcomes state, in simple terms, the relationship between cell function and cell structure for the following:  absorption – root hair cells  conduction and support – xylem vessels  transport of oxygen – red blood cells Differentiate cell, tissue, organ and organ system 3
  4. 4. What is a cell? Basic structural and functional unit of living things Building block of life All living things are made up of one or more cells How big is a cell? http://www.cellsalive.com/howbig.htm 4
  5. 5. What are inside a cell? Each living cell consists of living material called protoplasm Protoplasm is made up of cell membrane, nucleus and cytoplasm. Protoplasm is jelly-like, containing mainly water and many other substances Protoplasm in one part of the body may be different from another part of the body 5
  6. 6. Cell Membrane Cell membrane (plasma membrane) Structure Function Thin, partially Control movement of substances permeable in and out of the cell. Only allow layer around some substances to pass the cell through, small molecules such as glucose, oxygen and water can enter, but not others such as waste substances. 7
  7. 7. Cytoplasm Structure Function Jelly-like Acts as a medium for most substance made chemical activities of the cell to up mainly of occur; water (70% Contains enzymes and organelles. water)Organelles are subcellular structures(structures smaller than cells) thatperform specific jobs inside the cell.eg) mitochondria, ribosomes, chloroplasts,vacuoles 8
  8. 8. Nucleus Structure FunctionContains Controls cell activities, such aschromatin / cell repair and growth;chromosome(genetic Controls cell division.materials) 9
  9. 9. vacuole Structure FunctionA fluid-filled Store substances such as waterspace enclosed and food temporarily.by a membrane; vacuolesExiststemporarily inanimal cells. 10
  10. 10. Mitochondria Structure FunctionSmall, rod- Site where aerobic respirationshaped takes place and energy isorganelles; released.Highly foldedinner membrane (singular: mitochondrion; plural: mitochondria) 11
  11. 11. ribosomes Structure FunctionSmall, round Site where protein synthesis takesstructures; place.Can beattached to ERor found freelyin thecytoplasm. 12
  12. 12. Analogy Cell Structures: Chemical Factory:1. Nucleus Main office(Chromosomes that contain genes)2. Mitochondria Power Plant3. Ribosomes Factory workers4. Golgi Apparatus Packaging & Delivery5. Lysosomes Recycling Centre
  13. 13. Endoplasmic reticulum (er)(PURE) Two types:  Rough ER  Smooth ER 17
  14. 14. Rough ER (PURE) Structure FunctionRibosomes are Rough ER helps to transportattached to its proteins made by the ribosomes toouter surface, the Golgi apparatus for secretionhence its out of the cell.surface appearsrough whenseen under themicroscope 18
  15. 15. Rough ER (Pure) 19
  16. 16. Smooth ER (PURE) Structure FunctionSmooth ER does not Synthesises substanceshave ribosomes such as fats and steroids;attached to itsmembrane; Converts harmful substances into harmlessSmooth ER is more substances – Detoxificationtubular than roughER. It is connectedto the rough ER. 20
  17. 17. Smooth ER (Pure) 21
  18. 18. Golgi apparatus (PURE) Structure FunctionThe Golgi apparatus Stores and modifiesconsists of flattened substances made by thespaces surrounded by ER; andmembranes. packages these substances in vesicles forVesicles (small spherical secretion out of the cellspaces) fuse with one sideof the Golgi apparatus andpinch off from the oppositeside. 22
  19. 19. Golgi Apparatus (Pure) 23
  20. 20. Question (Pure) How are substances made by a cell released out of the cell? 24
  21. 21. Overview (Pure) Vesicles are tiny spherical spaces enclosed by a membrane. Vesicles containing substances made by the ER are pinched off from the ER These vesicles then fuse with the Golgi apparatus and release their contents into the Golgi apparatus for modification 25
  22. 22.  Secretory vesicles containing these modified substances are pinched off from the Golgi apparatus and moves towards the cell membrane They fuse with the cell membrane and release their contents outside the cell 26
  23. 23. Plant Cell 28
  24. 24. mitochondrion chloroplast Golgi complex central vacuole smooth endoplasmic reticulum vesicle rough endoplasmic cell wall reticulum plasma membrane nucleolusnucleus nuclear pore chromatin nuclear envelope ribosomes free ribosome
  25. 25. Plant Cell Its structures are similar to an animal cell except for the presence of:  Cellulose cell wall  Chloroplasts  One large central vacuole 30
  26. 26. Cell wall Structure FunctionMade of cellulose The tough cellulose protects theand surrounds the cell from injury and gives the cell aentire plant cell, regular shape.surrounding the cell The cell wall is fully permeable,membrane. unlike the cell membrane.Cellulose is a typeof carbohydrates 31
  27. 27. chloroplast Structure FunctionHas stacks of disc- Chlorophyll enables light energy tolike structures which be trapped and be converted intocontain the green chemical energy stored in foodsubstance called (glucose) during the processchlorophyll. photosynthesis. 32
  28. 28. vacuole Structure FunctionA plant cell has one Cell sap contains water andlarge central dissolved substances such asvacuole containing sugars, mineral salts and aminocell sap. acids.The large vacuole isenclosed by amembrane calledthe tonoplast. 33
  29. 29. Light micrograph of plant cells Plant cells – from epidermis of onion leaf
  30. 30. Light micrograph of animal cells http://iws.ccccd.edu/jbeck/Cellsweb/Cheekcells4.JPG Animal cells – from lining epithelium of cheek
  31. 31. MicroQues 1 - Differences structure Animal cell Plant cell Cellulose cell Absent Present wall Chloroplasts Absent Present Vacuoles Small, temporary Large, normally and many one present 36
  32. 32. Micro Ques 2The diagram shows four types of cells.Which cell does not contain a nucleus? ( A, B )
  33. 33. Micro Ques 3The diagram below shows a plant cell.Which of the following is not a function of part T?A to store food substancesB to secrete substancesC to store wastesD to store water ( B )
  34. 34. Micro Ques 4Which of the following statements describing the cellmembrane is incorrect?A It is supported by lignin to give it a regular shape.B It is a thin and elastic layer.C It is a partially permeable membrane.D It is mainly composed of fats and proteins. ( A )
  35. 35. Micro Ques 5Which of the following is a correct description of thepermeability of the cell membrane and cell wall in a plant? Cell wall Cell membraneA fully fullyB fully partiallyC partially fullyD partially partially ( B )
  37. 37. Cell Organisation Cell is the smallest working unit in a multicellular organism. 42
  38. 38. Different cells do differentwork Each cell type carries out its own particular kind of work. Cells have different shapes and structures to carry out different functions. 43
  39. 39. Specialised Cells
  40. 40. Tissue Formation A tissue is a group of similar cells which work together to perform a specific function Muscle Nerve tissue tissue 45
  41. 41. Specialised Tissues Tissues Main FunctionAnimalBlood Tissue Transports food and oxygenMuscle Tissue Produces MovementNerve Tissue Transmits impulsesEpithelial Tissue Protects CellPlantEpidermal Tissue Forms and protects surface of cellXylem Tissue Transports water and mineral saltsPhloem Tissue Transports food
  42. 42. Organ Formation An organ is made up of different tissues working together to perform a particular function 48
  43. 43. Organ in animals Made up of: •Glandular tissue •Muscle tissue •Connective tissue •Nervous tissue Stomach Etc. 49
  44. 44. Organs in plants Plants also have organs such as leaves, stems, roots and flower. 51
  45. 45. Micro Ques 6 Can you name some examples? Eg) In Animals: Respiratory system – Lungs Circulatory system – Heart Excretory system – Kidney Digestive system – Intestines, Stomach Reproductive System – Ovary, Testes In Plants: Reproductive System – flowers Transport system – Stem (xylem and phloem),roots
  46. 46. System Formation An organ system is made up of different organs working together to perform a main body function Respiratory system digestive system 53
  47. 47. Multicellular organism –Human Body Systems
  48. 48. Differentiation Differentiation is the process by which a cell becomes specialised for a specific function 3 examples:  Red blood cell  Xylem vessel  Root hair cell 56
  49. 49. Red Blood Cells
  50. 50. Red Blood CellFunction: Haemoglobin (red pigment) in cytoplasm transports oxygen from the lungs to all parts of the body. When haemoglobin combines with oxygen, oxyhaemoglobin is formed. 58
  51. 51. Red Blood CellAdaptations:i. Absence of nucleus so as to contain more haemoglobin and hence more oxygenii. Circular biconcave shape – increases surface area to volume ratio for faster diffusion of gases in and out of celliii. Elastic and can turn bell-shaped in order to allow the cell to squeeze through small blood vesselsiv. Contain a red pigment, haemoglobin, to allow oxygen to bind to the RBC to form oxyhaemoglobin. 59
  52. 52. Red Blood Cells
  53. 53. Xylem Vessels
  54. 54. Xylem Vessels
  55. 55. Xylem VesselFunctioni. Transport water and mineral salts from roots up the stem and to the leavesii. Provide mechanical support for the plant when bundled together 63
  56. 56. Xylem VesselAdaptationsi. Absence of cross-walls and protoplasm enable water to move easily through the lumen (central space).ii. Lignin deposited in the walls of xylem vessels strengthens it and prevents the vessel from collapsing.iii. Narrow and hollow lumen allows water to be moved easily up the stem. 64
  57. 57. Xylem vessels
  58. 58. Root Hair Cell Function Absorb water via osmosis and mineral salts from soil via diffusion. 66
  59. 59. Root Hair Cell Adaptations 1. long and narrow protrusion/ extension of an epidermal cell to increase surface area to volume ratio for more efficient absorption of water and mineral salts from soil. 2. It has a very large vacuole that contains concentrated cell sap solution, resulting in a lower water potential thus allowing absorption of water from the soil. 67
  60. 60. Root Hair Cell
  61. 61. Root hair cellVacuoleNucleus Root hair (long and narrow protrusion)
  62. 62. Micro Ques 7The table shows the presence, absence of a nucleus in threetypes of cells. Which of the following is correct? Red blood cell Root hair cell Xylem VesselA Present Absent AbsentB Present Absent PresentC Absent Present AbsentD Absent Present Present ( C )
  63. 63. The End 71