micro 101 (MJC)

Card Set Information

micro 101 (MJC)
2010-01-28 02:32:19
chapter 4

characteristics of prokaryotic and eukaryotic cells
Show Answers:

  1. Compare/contrast prokaryotic and eukaryotic cells
    • Prokaryotic cells (bacterial cells)
    • . No nucleus
    • Nucleoid Region.
    • binary Fission.
    • 70s ribosomes.
    • cell size and shape (smallest organisms) include; Coccus, Bacillus, Coccobacillus, Vibrio, spirillum, Spirochete).
    • cell wall (movement of substances across membranes).
  2. Compare/contrast prokaryotic and eukaryotic cells
    • Eukaryotic cells.
    • has a nucleus (plants, animal, fungi, and protoza.
    • Membrane-bound organelles.
    • mitosis & meiosis.
    • reproduce sexually.
    • 80s & 70s ribosomes
  3. Compare/contrast prokaryotic and eukaryotic cells
    Both have cell walls or plasma membrane.
  4. What are possible shape of Prokaryotic cells?
    • Coccus(s), Cocci (pl.); sphenical round.
    • bacillus (s), bacilli (pl.); rods.
    • Vibrio; curved.
    • spirillum; wavy.
    • spirochete; cork crew
  5. What is pleomorhusm?
    Baceria that vary widely in form (shape) even w/in a single culture.
  6. What are the possible arrangements of bacterial cells?
    • diplo=pairs.
    • stepto=chains.
    • tetrads=four cells cube.
    • garcinae= eight cells arranged in a cube.
    • staphlo= grape shaped
  7. Steptococcus tells you what about the organism?
    steptococcus translates into chains of special bacteria.
  8. How are the arrangements formed?
    in chains
  9. What are the function of the bacterial cell wall?
    • 1st Maintain shape of the cell.
    • 2nd Prevent cell from bursting when fluid flow into cell by osmosis.
  10. What is the major component of the bacterial cell wall?
    Major component is peptidoglycan. It is a large polymer thought of as one immense covalently linked molecule.
  11. How does the cell wall determine gram neg or pos. bacteria?
    • G+ has a thick (40) layer peptidoglycan.
    • third Amino Acid is lysine.
    • teichoic acid

    • G- has a thin layer.
    • diaminopimelic acid
  12. What is a outer membrane?
    Primay G- a bilayer membrane. Outer most layer of the cell wall attached to pepidoglycan by and almost continous layer of small lipoprotein molec. contains lipopolysacchard (endotoxin) identifis G-, LPs contains polysacchards and lipids A.
  13. What is it composed of?
    Lipopolysaccharide (polysaccharides and lipid A)
  14. What is endotoxin?
    Lipopolysaccharide (polysaccharide) released when cell wall of dead bacteria are broken down.
  15. In which bacterial cells do you find on OM?
    G-.....G neg.
  16. What is the periplasmic space?
    Gap between cell membrane and peptidoglycan.
  17. Which cells have the periplasmic space?
    ---> gap observed by electron microscopy of G neg bacteria.
  18. Compare/contrast the cell wall of gram +,gram -,and acid-fast bacteria?
    G pos; Thick layer of peptidoglycan. Have little amount of protein cell, cell wall retain chrystal violet stain. Lacks both outer membrane and a periplasmic space.
  19. Compare/contrast the cell wall of gram +,gram -,and acid-fast bacteria?
    G neg; cell wall thinner more complex than G+. cell membrane consistis of polysaccharides protein & lipids. Cell wall contains outer membrane & periplasmic space. Have lipo proteins and lipopolysaccharide in their walls.
  20. Compare/contrast the cell wall of gram +,gram -,and acid-fast bacteria?
    • Acid- fast bacteria; cell wall (mycobacteria) thick 60% lipids less peptidoglycan. Carbolfuchsin binds to cytoplasm (resists removal by an acid-alcohol mixture).
    • Lipids make impermeable to stains, protects from acid and alkalis slows growth because lipid impermeable nutrients.
  21. What organism have no cell walls?
    • mycoplasm genus bacteria.
    • shape pleomorhism (deficent strains are called L-form).
  22. Describe the fluid-mosaic model of the cell membrane?
    A phospholipid bilayer has two long fatty acid tail of hydrocarbon they are hydrophobic the head of the molecule consists of a charged phosphate group usually joined to charged nitrogen containing group. Head is hydrophilic.
  23. How are the phospholipids arranged?
    Phospholipids form a bilayer or two adjacent layers phosphate ends of lipid molecules extends towards the membrane surface and fatty acid ends extend inward.
  24. Define diffusion
    • Simple diffusion; is the net movement of particles from a region of higher to lower concentration.
    • facilitated diffusion; diffusion down a concentration gradient and across a membrane with the assistance of special pores or carrier molec.
    • osmosis; a special case of diffusuon in which water molecules diffuse across a selectively permeable membrane.
  25. What is osmotic pressure ?
    • Pressure at is required to prevent the net flow of water by osmosis.
    • The least amount of hydrostatic pressure required to prevent the movement of water from a given solution into pure water is osmotic pressure.
  26. define hypotonic
    hypotonic; water moves into cell
  27. define hypertonic
    hypertonic is water moves out of cell.
  28. define isotonic
    isotionic is water moves out and in equally.
  29. how will a bag or a cell behave in each type of solution and what way will the water flow?
    • Hypotonic water flows into the bag and will cause it to swell & burst.
    • Hypertonic water flows out of the bag and will cause it to shrivel.
    • Isotonic water flows equally and retains the same shape.
  30. Define active transport
    • Carrier protein molec aid in movement of molec against a concentration gradient.
    • *requires ATP and membrane proteins.
  31. Compare/contrast the ribosomes in prokaryotic vs. eukaryotic cell
    Eukaryotic ribosomes are 60% RNA & 40% protein larger than prokaryotic. Have a sedimentation rate of 80s subunits have sediment rates of 60s & 40s assembled in the nucleoli of nucleus. Prokaryotic & eukaryotic ribosomes provide sites for protein synthesis some are chains as polyribosomes. Free floating ribosomes make protein for use in cells.
  32. what are the clinical applications that exploit this difference?
    Antibiotics such as streptomycin & erythromycin bind to 70s ribosomes specifically & disrupt bacterial protein synthesis w/out harming Eukaryotic host which mostly has 80s ribosomes.
  33. What is the nucleoid region?
    Also known as nuclear region of DNA but has some RNA and protein associated with it. May contain chromosomes and plasmids.
  34. Generally what is the characteristics of bacterial chromosomes?
    One large circular chromosomers, two circular chromosomes on circular and 1 linear chromosomes circular molec. of DNA called plasmids.
  35. What are plasmids and how are they used?
    Plasmid are smaller circular molec. of DNA. They contain genetic information in plasmids supplement info in the chromosomes.
  36. What are endospores and what is their purpose?
    • A special struture found in bacteria (Bacillus sp. & Clostridium sp.)
    • *Requires time and energy to make spores
    • **Helps the bacterial cell to survive when conditions become unfavorable
    • ****resistant to heat, drying, acids, bases, certain disinfectants and radiation
    • ******known to be remain dormant for 10,000yrs.
  37. What are flagella, and how might they be arranged?
    • Flagella are long thin helical appendages that make bacteria motile.
    • Arrangements include
    • monotrichous: one end (polar).
    • anphitnchous: one at each end (polar).
    • Lophotrichous: tuft of flagella at one or both ends.
    • Peritrichous: flagella all over the surface.
    • Atrichous: no flagella (no motility)
  38. How are flagella anchored in gram-positive and gram-negative bacteria?
    G-neg bacteria have a pair of rings embedded in the cell membrane and another pair of rings associated with peptidoglycan & lipopolysaccaride layers of the cell wall. G+ pos. bacteria have one ring embedded in the cell membrane and another in the cell wall.
  39. Flagella in Eukaryotic cells?
    • Longer and more complex than those of prokaryotic cells. Constist of two central micro tubules and 9 pairs of peripheral microtubules surrounded by a membrane. Each fiver is a microtubule made of the protein tubulin. Move like a whip.
    • Found mostly in protozoa. Most have one flagella some have 2 or more.
    • spermatozoa is the only human flagellated cell..
  40. Describe a run and tumble
    • When flagella of a bacteria rotate counter clock wise.
    • Direction the flagella bundle together and push the bacterium fairly strait this is the run.
    • Reverse & rotate in a clockwise direction the bundle comes apart each flagella acts independantly.
    • The cells tumble about in randum direction= tumble.
  41. What is chemotaxis?
    • Pos./neg chemotaxis.
    • movement toward or away from a substance in their environment.
    • Toward is an attrachtant; positive
    • Away is repleant; negative
  42. What is phototaxis?
    • Some bacteria can move toward or away from the light.
    • Pos. phototaxis is toward light.
    • Neg. phototaxis is away from light
  43. What are pili and how are they used ?
    • Pili are tiny hollow projections.
    • They attach bacteria to surfaces.
    • Do not movement.
  44. How are pile used in conjugation?
    • Long conjugation pili (F-pili):
    • tube in which DNA is transferred form one cell to the next.
  45. How are pili used in attachment?
    • Attachement pili or fimbriae;
    • help bacteria to adher to surfaces such as cell surphases and the inter faces of water and air contribute to pathogenicity of certain bacteria.
  46. How are pile used in pellicle?
    • Some aerobic bacteria form a shiny of fuzzy thin layer at the water/air interface of a broth culture.
    • This layer is the pellicle.
    • Consist of many bacteria that adhere to the surface by their attachment pili.
  47. Glycocalyx
    refers to all polysaccaride - containing substanced found external to the cell wall from the thickest capsule to the thinnest...slime layer.
  48. What is a capsule and why are encapsulated bacteria more difficult for their host to fight?
    • A capsule is a protective structure outside the cell wall of the organism that secretes it.
    • Capsules prevents host defense mechanism such as phagocytosis from destroying the bacteria.
  49. What is a slime layer and function?
    • A less tightly bound to the cell wall and is usually thinner than a capsule.
    • Protects cell from drying out, traps nutriunts near the cell.
    • Sometimes bind cells together.
    • Slime lalyer allow bacteria to adhere to objects in their environments, such as.
    • rock surface.
    • root hairs of plants
  50. List Eukayotic cells
    • Nucleus.contain RNA that assembles ribosomes.
    • Have chromosomes that contain DNA.
    • Golgi apparatus.Stores, transports and receives substances form the er packages.
    • Ribosomes.Provide site for protein synthesis.
    • Endoplasmic reticulm.smooth ER, synthesizes lipids, Rough ER manufacture proteins.
    • vacuoles.store starch glycogen or fat for energy.
    • mitochondria.carry out the oxidative rxn that capture energy in ATP
    • Cytoplasm.semifluid substance consisting mainly of water.
    • Chloroplast.carrys out photsynthesis.
    • lysomes.fus w/vacuoles and release enzymes to digest the substance inthe vacuoles.
    • peroxisomes.filled w/enzymes that oxidize AA in animals cells and fats in plant cells.
    • Cytoskeleton.network of protein fiber microtubles and microfilaments that supports and gives ridgity to cells
  51. What are celia?
    • Cilia are shorter and more numerous than flagella, mainly in protozoa passes thru strokes and recovery cycle.
    • Propell's fluids and dissolves particles of bacteria mucus.
  52. What is pseudopodia?
    • False feet.
    • temporary projections of cytoplasm associated w/amoeboid movement. occurs oily in cells w/o walls.
  53. Explain the endosymbiotic theory
    Organelles of eukaryotic cells arose form prokaryotic cells that had developed a symbiotic relationship w/the eukaryotic to. When one organism lives inside another organism not just close contact.
  54. What evidence supports this theory about the endosymbiatic theory?
    • Mitochondria and chloroplast; same size as prokaryotic cells and have own DNA.
    • Organelle DNA & ribosomes carry out protein synthesis as it occurs in bacteria.
    • Antibiotic inhibiting protein synthisis in bacterail ribosomes also inhibit it in ribosomes of chloraplasts and mito.
    • mito. and chloro divide indepentality of cell by means of binary fission.
    • Double membrane structure of mito & chloro resemble syanobacteria.
    • Mito DNA resemble DNA of rickettsia.
  55. What example found of endosymbiotic theory in nature?
    • Certain eukaryotes living in low-oxygen enivonments lack mito yet they have bacteria that live inside them and serve as surrogates mito.
    • Protist live symbiotically in lermite termites guts in torn colonized by symbiotic bacteria of the same size and distribution they frunction better in low O2 conditions better that mito
  56. Endocytosis
    • made from portions of plasma membrane.
    • form invanation & surround substances from outside cell and enter the cell
  57. Exocytosis
    vesicles inside cell fuse w/plasma membrane and extrude their contents.