Microbiology exam 1

The flashcards below were created by user janieu on FreezingBlue Flashcards.

  1. what are viruses, viroids, and prions termed?
    • microbes, since they aren't living.
    • they are acellular infectious agents
  2. Describe what viruses are
    • use host to replicate
    • obligate intracellular parasites: inactive outside of host
  3. Describe what prions are
    • -infectious proteins
    • -contains no genetic material
    • -replicate by changing a normal protein into an infectious one
    • -misfolded versions of regular cellular proteins
    • -transmitted by ingestion
  4. How do bacteria divide and what does it determine?
    • -divide by binary fission
    • -determines the shape and organization of bacteria
  5. Describe the shapes of bacteria
    • cocci: sphere
    • bacillus: rod
    • coccobacillus: short rod/ long sphere
    • vibrio: curved rod
    • spiral: spiral rod
    • spirochete: helical rod, motile
    • pleomorphic: no specific shape
  6. Describe how bacteria groups grow and divide
    • diplo: two
    • strepto: chain
    • staphlo: clusters
    • packets: tetrads
  7. Describe the cytoplasmic membrane of bacterial cell
    • -phospholipid bilayer: hydrophilic head, hydrophobic tail
    • -selectively permeable
    • -small hydrophobic molecules such as water, O2, and CO2 can enter and leave cell by simple diffusion
  8. describe what different osmotic gradients do to cells
    • -hypotonic: cell put in solution with less solute concentration than than its own so water from the solution flows in cell and can cause it to lyse
    • -hydrophilic: cell put in solution with higher solute concentration and water from the cell flows out in the solution causing cell to shrink
    • -water tends to flow from hypo to hyper tonic solutions
  9. describe energy role of cytoplasmic membrane
    • -electron transport chain transfers electrons and moves protons outside of the cell
    • -causes an electrochemical gradient
    • -proton motive force: ejects protons from the cell in which there becomes electrochemical gradient between protons and hydroxyl anions
  10. describe the transport proteins
    • -facilitated diffusion: transporter that allows substances to move down its concentration gradient across the membrane
    • -active transport: use proton motive force as an energy source to move substances against concentration gradient
    • -group translocation: modifies molecule chemically as its being transported across membrane
  11. describe protein secretion
    • -membrane bound protein structures allow bacteria to excrete substance into environment or cell
    • -signal sequence tags pre protein and once outside cell preprotein can unfold into it's functional shape
  12. describe peptidoglycan
    • -composed of sugars and proteins
    • -a single unit is composed of two sugars, N-acetylmuramic acid (NAM) and N-acetylgucosamine (NAG) that are linked together w/ 5 amino acids attached to the NAM sugar
    • -peptide bridge are found in Gram+ cells
    • -the glycan chains (NAM and NAG) are crosslinked through tetrapeptide chains to create peptidoglycan
  13. how is a peptidoglycan monomer inserted into a growing cell wall
    • -autolysins cut the cell wall
    • -Transglycosidases link the sugars
    • -Transpeptidases cross link peptide side chain to another
  14. describe Gram Positive cell wall
    • -peptidoglycan w/ peptide interbridges
    • -contains teichoic/lipoteichoic acid
    • -linked to NAM
    • -helps stabilize gram positive cell wall
    • -lipoteichoic acid helps anchor cell wall to bacterial plasma membrane
    • -gives cell negative charge
  15. describe the periplasm of Gram negative cell wall
    • -periplasm: space b/w plasma membrane and outer membrane and contains peptidoglycan layer and enzymes
    • -peptidoglycan is only a sheet or two thick
    • -the peptide side-chains are directly linked and have no inter bridge
    • -lipoprotein connects outer membrane to peptidoglycan
  16. describe the outer membrane of Gram negative cell
    • -has lipid bilayer with embedded porin proteins that allow molecules to enter into the periplasmic space
    • -has lipopolysaccharide (LPS): composed of Lipid A and organized series of polysaccharides
    • -Lipid A is conserved in most gram-negatives and anchors LPS to lipid bilayer
    • -core polysaccharide is conserved in specific genus and species
    • -O-side chain is variable with in species
    • -LPS is known as an endotoxin, lets body know that Gram negative have invaded
Card Set:
Microbiology exam 1
2013-09-12 23:01:05

Show Answers: