1. Cell Structure and Function

2. The Cell Theory v All living things are composed of cells. v Cells are the basic units of structure and function in living things. v All cells come from pre- existing cells.

4. Cell Structure v Most cells have three basic structures. – cell membrane (outer boundary) – cytoplasm (filling) – nucleus (control center)

5. v All cells have a cell membrane and cytoplasm.

6. v However some do not have a nucleus. These are called Prokaryotes. v However some do not have a nucleus. These are called Prokaryotes. (bacteria)

7. v Cells with a nucleus are called eukaryotes. v Cells with a nucleus are called eukaryotes. (plant, animal, fungus and protists) Nucleus

8. v Separates and protects the cell from its surroundings. v Regulates what enters and leaves the cell. v Made of two lipid layers: (Phospholipid bilayer) Cell Membrane

9. Hydro- phyllic (Phos- phates) Hydro- phobic (Fatty acids) Phospholipid Bilayer The Cell Membrane

10. Cytoplasm v The area between the cell membrane and nucleus. v Contains structures called organelles and each one performs a specific job.

11. Cytoplasm

12. Nucleus (Control center) v Contains DNA which are the instructions for making molecules the cell needs.

13. Nucleus (Control center) v Directs the activities of the cell. v Surrounded by a membrane called the nuclear membrane or nuclear envelope.

14. Nucleus

15. Nucleolus

16. v A small region of the nucleus made up of RNA and proteins. v The nucleolus makes ribosomes.

17. Nucleolus Nucleus

18. Ribosomes v Found in prokaryotic and eukaryotic cells v Protein factories. v Some ribosomes are attached to the endoplasmic reticulum.

19. Ribosomes v Others are free in the cytoplasm. v Smallest organelle.

20. Ribosomes Rough ER

21. Endoplasmic Reticulum v Two forms Rough ER Smooth ER

22. Endoplasmic Reticulum Smooth ER : no ribosomes are attached. Special enzymes and chemicals are stored here. Lipids (fats) are produced

23. Endoplasmic Reticulum Smooth ER : also resp. for prod. of phospholipids for cell membrane.

24. Rough ER : has ribosomes attached. After proteins are made in the ribosomes they are inserted in the rough ER where they can be modified. Endoplasmic Reticulum

25. Rough ER : from the ER, proteins are sent to the Golgi Apparatus Endoplasmic Reticulum

26. Golgi Apparatus (UPS) v modifies, collects, and packages molecules in the cell. v Also distributes the molecules to where they need to be in the cell.

27. Golgi Apparatus

28. Lysosomes v Cleanup crews for the cell. v Lysosomes are formed in the Golgi apparatus.

29. Lysosomes v Contain chemicals and enzymes that digest and breakdown waste particles.

30. Lysosome in action:

31. Vacuoles (Warehouse) v Storage tanks in the cell. v Store materials like water, salts, proteins, and carbohydrates. v Plants have only one big vacuole filled primarily with water.

32. Vacuoles (Warehouse)

33. Cytoskeleton v The framework of the cell. v Made of microfilaments and microtubules v Provide support and are often involved in cell movement.

34. Mitochondria(Generator) v Generator of the cell. v Changes chemical energy stored in food (sugar) into compounds easier for the cell organelles to use (ATP).

35. Mitochondrion

36. Chloroplast (Solar Panel) v Where photosynthesis takes place v Found only in plant cells and algae.

37. Chloroplast (Solar Panel) v Traps energy from sunlight and changes it into chemical energy (makes sugars).

38. Plant Cell Chloroplast

39. Cell Wall v In addition to the cell membrane, plant (& fungus) cells have a cell wall. v Provides extra support. v Made up of cellulose and lignin

40. Cell Wall Found outside the cell membrane

41. Movement of materials through the cell membrane. v Cells must take in materials, and release waste products. v Molecules must be able to move in and out of the cell.

42. Movement of materials through the cell membrane. v They do this by diffusion.

43. Diffusion v The process by which molecules move from areas of higher concentration to areas of lower concentration. (spread out)

44. Diffusion v Driven by the random movement of molecules.

45. Diffusion v Two factors determine if diffusion takes place equilibrium and permeability.

46. higher conc. lower conc. membrane Diffusion

47. Equilibrium v Equilibrium is when the concentrations on both sides of the membrane are equal.

48. Equilibrium Semi-permeable membrane

49. Permeability v If a molecule can diffuse across a membrane, the membrane is permeable.

50. Permeability v If a molecule cannot diffuse across a membrane, the membrane is impermeable to that membrane.

51. Selective Permeability v Membranes are permeable to some molecules and impermeable to others. v These membranes are described as selectively permeable or semi- permeable.

52. Osmosis v Osmosis is a special type of diffusion: v The diffusion of water molecules through a selectively permeable membrane.

53. v There are three types of transports across a membrane. –passive transport (diffusion) –facilitated diffusion –active transport

54. Passive Transport v Energy is not required for movement across the membrane to occur. v Diffusion and osmosis are examples

55. Facilitated Diffusion v A carrier protein “helps” the molecule to enter or leave the cell. (Passive)

56. Active Transport v Energy is required for movement across the membrane to occur. v Molecules move from low to high concentration.

57. Two types of active transport: –Protein pumps: Pumps specific ions –Endocytosis: cell engulfs (eats) material. Active Transport

58. Pumps v Proteins stuck in the membrane act as a doorway into the cell. v Allows only specific things through the doorway. v Energy is required to open the door

59. Pumps

60. Endocytosis

61. Endocytosis v Type of active transport when the membrane surrounds material and pulls it into the cell

62. Endocytosis Types v Phagocytosis v Pinocytosis v Receptor Mediated Endocytosis

63. Phagocytosis v “ Cell Eating” v Bringing large molecules across the membrane. v Membrane becomes a vacuole when entering the cell

65. Pinocytosis v “Cell Drinking” v Moving fluids and ions across a membrane. v Usually going against the concentration gradient

66. Ion concentration outside the membrane is less than inside

67. Membrane surrounding ions and fluids

68. Vacuole

69. Receptor Mediated Endocytosis v Same process as pinocytosis. v Specific ions are moved across the membrane

70. Receptor Mediated Endocytosis v Receptor proteins trigger when endocytosis should begin

73. Exocytosis v Opposite of endocytosis v Process when cell removes waste from cytoplasm

74. v Vacuole or lysosome fuses with cell membrane and releases materials outside the cell