MBioCh4

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Author:
victimsofadown
ID:
173507
Filename:
MBioCh4
Updated:
2012-09-26 01:10:26
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MBioTest1
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MBioTest1
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  1. Name and describe the 3 basic bacterial shapes and their arrangements
    • Coccus: single, diplococci, streptococci (chain), tetrad, sarcinae (two tetrads on top eachother... cube-like), staphylococci (cluster)
    • Bacillus: single, diplobacilli, streptobacilli (chain), coccobacillus (very short rod)
    • Spiral: single arrangement only, vibrio (curved rod), spirillum (helical shape, rigid body), spirochete (helical shape, flexible body)
  2. Define glycocalyx and explain how it contibutes to bacterial virulence + types
    • Sugar coat made of polysaccharides and/or polypeptides
    • Protection against phagocytosis, dessication.
    • Aids in attachment (eg teeth)
    • Can act as nutrient reserve
    • Capsule: attached to cell wall, very difficult to remove
    • Slime layer: thinner, not as well organized
    • Extracellular polysaccharide: very thin, easily removed layer
  3. Name and explain the 4 arrangements of flagella
    • Peritrichous: all over surface
    • Monotrichous: one flagellum, one end
    • Lophotrichous: multiple flagella one end OR multiple flagella both ends
    • Amphitrichous: one flagella, both ends
  4. Explain the functions of flagella, fimbriae, axial filaments, and pili
    • Flagella: motility (operates like a rotor)
    • Fimbriae: hair-like extensions, allow attachment (important to pathogenic bacteria)
    • Axial filaments: endoflagella covered by sheath, corkscrew rotatiojn to move cell, aid penetration of tissues, found in spirochetes
    • Pili: Used to transfer DNA between cells during conjugation.  Can be used for motility
  5. Explain the function, composition, and characteristic of the cell wall
    • Maintain cell shape
    • Acts as barrier to environment
    • Protects against osmotic lysis
    • Major site of action for most antibodies
    • Made of peptidoglycan
  6. Compare and contrast the cell walls of Gram negative, Gram positive bacteria, and mycoplasmas
    • Gram positive: Thick layer of peptidoglycan.  Teichoic acids stabalize the cell wall.  Thin periplasm (space between cell membrane and cell wall)
    • Gram negative: Thin layer of peptidoglycan.  Thick periplasm that contains degradative enzymes to break down food before it reaches membrane.  Outer membrain that contains lipids and polysaccharides (protection from phagocytes, complement, and antibiotics)
    • Mycoplasmas: lack cell walls, have streols in plasma membrane
  7. Explain assembly of the cell wall and the effects of Penicillin
    • Peptidoglycan contains a sugar backbone (polymer of NAG and NAM) linked together by peptide cross bridges
    • Penicillin inhibits the peptide pridges in peptidoglycan, weakening cell walls and causing them to burst if they are growing.
  8. Describe the function of the plasma membrane
    • Retain cytoplasm and cell contents
    • Serve as selective barrier
    • Enzymes for ATP production (electron transport chain)
    • Photosynthetic pigments on foldings called chromatophores or thylakoids
  9. Discuss how materials move across the membranes
    • Simple diffusion: [high] to [low]
    • Facilitated diffusion: requires transporter protein
    • Active transport: against gradient (requires energy)
    • Group translocation: molecule being transported is chemically altered (eg phosphorylated)
  10. Describe how a bacterial cell would respond in a hypertonic, isotonic, or hypotonic environment
    • Hypertonic: H2O leaves cell. Plasmolysis - membrane pulls from cell wall and cell dies
    • Isotonic: No net movement of water
    • Hypotonic: H2O enters cell. Cytolysis - if cell wall is weak cell will burst.
  11. Describe the structure and function of ribosomes
    • Prokaryotic: Small subunit (30S) + large subunit (50S) = Complete ribosome (70S)
    • Differ from eukaryotic 80S ribosomes, so they can be targeted by antibiotics
  12. Define endospores, explain under what conditions they would be formed and by what type(s) of bacteria
    • Dehydrated, resting cells with a thick coat. 
    • Survival mechanism in response to harsh environments
    • Formed by Bacillus and Clostridium genera
  13. Discuss the endosymbiotic theory and give the evidence that support it
    • Chloroplasts and mitochondria came from englufed bacteria / symbiosis
    • Similar size/shape to bacteria
    • Single circular DNA
    • 70S ribosome
    • Reproduce autonomously by binary fission
    • Ectosymbionts move independent of protozoan
  14. List differentiating factors between eukaryotes and prokaryotes
    • Prokaryote: one circular chromosome, no histones, no membrane-bound organelles, bacteria have peptidoglycan, archaea have pseudomurein, binary fission
    • Eukaryote: paired chromosomes in nuclear membrane, histones, membrane-bound organelles, polysaccharide cell walls, mitotic spindle

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