1. Cells Chapter 3

2. Humans have about 75-100 trillion cells They vary in shape and size Shape & size--closely related to function

3. 2 Major Parts 1) Nucleus Inner most part The control center

4. Surrounded by a thin double layered membrane (nuclear envelope)

5. 2) Cytoplasm Fluid that surrounds the nucleus Encircled by the cell membrane (AKA: plasma membrane)

6. -Cytoplasm is responsible for metabolism -Appears to be clear liquid with tiny specks -Where all cell activities occur

7. Within the cytoplasm are parts called Organelles They conduct special metabolic functions for all cells

8. Cell Membrane (Plasma Membrane) Very thin—only visible with electron microscope Is flexible and elastic

9. Keeps the cell intact Is selectively permeable; controls what enters and leaves the cell

10. Composed of lipids and proteins Is a bi-layer of phospholipid molecules

11. Organelles: Endoplasmic Reticulum (ER)—very complex Functions as tubular communication system…

12. and it transfers molecules from one part of the cell to the other Helps produce ribosomes

13. Rough ER Contains ribosomes Ribosomes Structure: particles composed of proteins and RNA molecules

14. Function: They synthesize proteins Golgi Apparatus Structure: group of flattened membrane sacs

15. Function: packages protein molecules for transportation and secretion

16. Mitochondria Structure: fluid filled sacs, which vary in shape and size

17. Function: release energy from food molecules & transform energy into usable forms

18. Lysosomes Structure: membranous sacs Function: digests worn cellular parts or foreign objects that enters cell

19. Centrosome Structure: non- membranous structure, composed of 2 rod-like centrioles

20. Function: helps distribute chromosomes to new cells during cell reproduction

21. Vesicles Structure: membrane sacs Function: contain various substances that enter & exit the cell

22. Cilia & Flagella Structure: motile projections attached beneath the cell membrane

23. Function: propels fluid over cellular surfaces and enable movement Flagella=sperm Cilia=epithelial cell

24. Microfilaments & Microtubules Structure: thin rods and tubes

25. Function: provide support to the cytoplasm and help substances and organelles into the cytoplasm

26. Movement Through Cell Membrane *Passive mechanisms require NO energy Chart 3.2 page 61

27. 1. Diffusion A process by which molecules or ions become scattered or spread spontaneously from region where they are in higher…

28. concentration toward region where they are in lower concentration

29. It is by diffusion that oxygen and carbon dioxide molecules are exchange between air and blood in the lungs, and between the blood and the cells of various tissues

30. When molecules have been equally distributed, a state of Equilibrium results

31. Facilitated Diffusion Occurs in most cells It is when a glucose molecule combines with a protein carrier…

32. there, the glucose and the carrier form a compound; they then can diffuse through the other side of the lipid bi-layer

33. Once inside, the glucose is released and the carrier returns to the outside

34. Insulin A special hormone that promotes facilitated diffusion of glucose through certain cells

35. Osmosis Special case of diffusion (diffusion of water)

36. Occurs when water molecules diffuse from a region of higher concentration to a region of lower concentration, through a selectively permeable membrane

37. Osmotic Pressure The amount of pressure needed to stop osmosis

38. 3 Types of Osmosis

39. 1) Hypertonic Solution Greater concentration of solute outside the cell than inside (more water leaving than entering) *Cell shrinks

40. 2) Hypotonic Solution Greater concentration of solute inside the cell than outside (more water is entering than leaving) *Cell swells

41. 3) Isotonic Solution Same concentration inside and outside the cell *Cell stays the same

42. Active Transport (p 61) Molecules are carried through the cell membranes by other molecules from a lower concentration to a higher concentration…

43. through the use of special carrier molecules

44. *Endocytosis Particles are too large to enter the cell by diffusion or active transport A vesicle is made

45. *Pinocytosis (cell drinking) Cells bring in droplets of liquid from its surroundings. The cell becomes indented by the liquid

46. The cell forms a seal around the droplet. The liquid particle becomes part of the cytoplasm

47. *Phagocytosis Exact same process as pinocytosis, except it brings is solids

48. *Exocytosis (cell puking) “Junk” is spit out of cell

49. Life of a Cell Life cycle of a non- reproductive cell…

50. The series of changes that a cell undergoes from the time it is formed until it reproduces is called its Life Cycle (cell cycle)

51. Cell cycle is made up of Interphase (G1 phase, G2 phase, S phase) and mitosis

52. Interphase Cell grows and prepares for mitosis

53. Mitosis Gap 1 (G1) Cells that cease division S Phase (DNA synthesis) Gap 2 (G2)

54. Mitosis Division of nuclear parts and also cytoplasm Contains information on DNA formation

55. Mitosis is continual (20 hours) Stages: (PMAT)

56. Prophase First indication of something taking place Chromosomes become scattered throughout the nucleus (appear)

57. Metaphase Spindle fibers attach to centromere Chromosomes line up on the equator of the cell

58. Anaphase Centromeres split Chromatids move to opposite poles (to ends of cell)

59. Telophase Cell membrane starts to divide cytoplasm