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  1. Cells Chapter 3 Bio 156 Fall 2006

  2. What is the Cell Theory? • All organisms are made of cells. • The cell is the smallest unit of life. • New cells come from pre-existing cells.

  3. What are microscopes?tools used to view cells • Compound light microscope: light rays focused by lenses, viewed by the eye, magnifies up to 1000X

  4. Dissecting microscope: • For observing surface details of objects, magnifies up to 30X Penny

  5. Electron microscopes • For viewing details, magnifies 1,000,000X TEM Surface of a cell, cilia

  6. How are cells classified? according to their internal organization? • What structures do all cells have? • Cell or plasma membranes: living phospholipid bilayer and associated proteins

  7. Internal organization of cells cont….. • Plant cells also have a rigid cell wall made of cellulose • Cytoplasm: a semifluid gel inside the cell that contain cell contents

  8. What are Eukaryotic Cells? Have a “true nucleus”, plant and animal cells • What are organelles?"little organ", cellular structures that perform specific functions • What does the nucleus do?control center of the cell

  9. What are prokaryotic cells? “before" the nucleus (bacteria) Bacillus polymyxa DNA: single circular DNA in a nuceloid region • Ribosomes: enzymes that synthesize proteins • Cell membrane: regulates transport in/out of the cell • Cell wall for strength, may have a capsule or slime layer

  10. How does cell structure reflect cell function? • Simple cuboidal epithelium (400x) is made up of one layer of cube-shaped cells.  These cells frequently make up the tubes of your body.

  11. How does cell structure reflect cell function….. • Blood Cells • Why do you think Red Blood Cells don’t have a nucleus and White Blood Cells do? • (hint: think about their functions)

  12. How does cell structure reflect cell function… • Skeletal muscle (400x) is striated • What is the function of these cells? • Why do you think these are long cells?

  13. How does cell structure reflectcell function… • Plant Cell Anacharis (Elodea) leaf cells (1000x).  • What do you think is the function of these cells?  • How is the function dependent on the structure?

  14. How does cell structure reflect cell function… Potato cells with stained leucoplasts (100x).  • The leucoplasts (starch storage units) have been stained with gram iodine (stains for starch)

  15. What limits cell size? Surface area-to-volume ratio needs to be greater for an exchange of materials Microvilli: some cells increase surface area by micro-extensions called microvilli

  16. What is a plasma membrane made of? (how is a cell membrane like a house?) • Phospholipids:a. polar heads (hydrophilic or water soluble) b. nonpolar tails (hydrophobic or not water soluble) • Cholesterol: gives strength to the cell membrane • Proteins: transport, communication

  17. What is the fluid-mosaic model of the cell membrane? • How is itfluid? (flows, pliable) phospholipid bilayer • How is it a mosaic? proteins partially or wholly embedded

  18. What are channel proteins? Space where a substance moves across the membrane What are carrier proteins? Combine with a substance and help it move across the membrane

  19. What are receptors? Specific shape that allows a molecule to bind to it, ex) hormone What are glycoproteins?For cell to cell identification

  20. How are membranes selectively permeable?Allows some molecules to pass through and not others • What is passive transport? • Doesn't need energy to happen, goes with concentration gradient • What is diffusion? Movement of molecules from high to low concentration

  21. What is osmosis? Diffusion of water into and out of cells • What is a solute? usually a solid • What is a solvent? usually a liquid • Define tonicity: based on concentrations of solutes

  22. What are isotonic solutions? Same concentration of solutes on either side of the membrane

  23. What are hypotonic solutions? • Low solutes in solution, water enters the cell, hemolysis

  24. What are hypertonic solutions? • High solutes in solution, causes water to leave the cell (water follows salt), crenation

  25. What is turgor pressure? Plant cells swell in response to a hypotonic solution Put some wilted celery in a glass of cool water. If it has not wilted too much, it will become stiff again. This is because of turgor pressure when the plant cell vacuoles become filled with water, push against the cell walls and become firm.

  26. What is facilitated transport?Carrier proteins assist movement of specific molecules

  27. What isactive transport?Requires ATP to move molecules against their concentration gradient • What is the Na-K pump? • Concentrates more Na+ outside, K+ inside cell membranes

  28. What is Exocytosis or Endocytosis? Move materials outside or inside the cell

  29. What is Phagocytosis? “Cell eating”, white blood cells

  30. What isPinocytosis?“Cell drinking”, root cells get water

  31. What is receptor-mediated endocytosis? Coated proteins attract specific molecules to the cell surface

  32. Construction of the Cell Membrane • This is an interactive activity • Construction of the Cell Membrane • In this activity you will learn about the cell membrane structure by assembling it. Interactive exercise from Wisc-Online.

  33. How do internal structures carry out specific functions? • What are the structures of the nucleus? • Nuclear membrane: has nuclear pore spaces • Nucleolus: forms RNA and ribosomes • Chromatin: all of the DNA molecules

  34. What do ribosomes do? Assemble proteins

  35. What does endoplasmic reticulum (ER) do? • Makes and transports large molecules • Smooth ER: enzymes make lipids, steroids • Rough ER with ribosomes (RNA): have ribosomes for making protein

  36. What does the Golgi apparatus look like? Stacks of sacules (like pancakes) • What is its function? • Stores and distributes products from ER • Processes, packages and secretes • Breaks off pieces as vesicles (small sac)

  37. What are Vacuoles? Large membranous sacs for transport and storage • What do lysosomes do? • Digestive enzymes in vesicles • What are Peroxisomes? • Vesicles with enzymes that destroy toxins

  38. What are mitochondria? Site for aerobic respiration, "burns food" • Produces ATP “cell's powerhouse” • Cristae: inner membrane increases surface area for metabolism • Matrix: inner fluid-filled space

  39. What are chloroplasts? Organelles only found in plant cells • Photosynthesis: use solar energy to make carbohydrates • Thylakoids: interconnected flattened sacs • Grana: stacks of thylakoids (granny's pancakes) • Stroma: syrupy fluid filled space (syrup)

  40. What provides cells with structure for support and movement? • Cytoskeleton? interconnected microtubules and microfilaments • Cilia: small whips, move cell, or fluids across a surface • Flagella: larger whip, moves cell like an oar on a boat

  41. Centrioles in animal cells for spindle fibers during mitosis, pull chromosomes apart

  42. How do cells use and transform matter and energy? • What are metabolic pathways? When one chemical reaction leads to another ex) A + B -> C + D • What are reactants? participate in a reaction, ex) A + B -> (enzyme) • What are products? result from a reaction, ex) C + D

  43. What is Anabolism? Building up of larger molecules, takes energy (endergonic) What is Catabolism? Breaking down into smaller molecules, gives up energy (exergonic)

  44. What is ATP? A universal packet of energy used in cells • ATP = adenosine triphosphate (Adenine-ribose-P-P-P) • Exergonic:the energy currency of the cell • ATP -> ADP + P + energy • Endergonic: • ADP + P + energy -> ATP

  45. What is cellular respiration? Chemical reactions that produce ATP in cells • What is glycolysis? breaks down glucose (C6) -> 2 pyruvate (C3) + 2 ATP • Where does it take place? in the cytoplasm, in all cells, no O2 needed • How does it get started? it needs 2 P from 2 ATP activate glucose

  46. What is aerobic respiration?Respiration with oxygen • Where does it take place? Inside the mitochondria: yields 36-38 ATP • What does the Krebs cycle do?1) pyruvate is broken down to O2 + acetyl group (C2) -> 2 CO2 + 2 ATP 2) NAD+ and FAD + H2 -> NADH and FADH2 -> electron transport system

  47. What does theelectron transport system do? • Coenzyme carriers move electrons to make 32-34 ATP

  48. What is fermentation? Alternative pathway of energy when no oxygen is present • Glycolysis first • Alcoholic fermentation: • Glucose is broken down to pyruvate, then to Alcohol + CO2 + 2 ATP • Used for: brewing, baking

  49. What is lactic acid fermentation? • Glucose -> pyruvate –> lactate + 2 ATP • Used in making yogurt, sour cream, cheese, sauerkraut • In O2 starved muscles, oxygen debt: O2 + lactic acid to pyruvate