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MCB 2610 Exam 3 Question and answers correctly solved 2024/2025 CA$20.19   Add to cart

Exam (elaborations)

MCB 2610 Exam 3 Question and answers correctly solved 2024/2025

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MCB 2610 Exam 3 Question and answers correctly solved 2024/2025 MCB 2610 Exam 3 functions of bacterial cell wall - correct answer maintains the shape of the bacterium, helps protect the cell from osmotic lysis (rupturing), helps protect from toxic materials, may contribute to pathogenicity ...

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  • October 17, 2024
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  • 2024/2025
  • Exam (elaborations)
  • Questions & answers
  • MCB 2610
  • MCB 2610
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MCB 2610 Exam 3
functions of bacterial cell wall - correct answer ✔maintains the shape of the
bacterium, helps protect the cell from osmotic lysis (rupturing), helps protect
from toxic materials, may contribute to pathogenicity


cell wall - correct answer ✔peptidoglycan (murein)- rigid structure that lies
just outside the cell membrane; two types based on gram stain- gram positive
and gram negative


peptidoglycan structure of cell wall - correct answer ✔meshlike polymer of
identical subunits forming long strands; two alternating sugars NAG and NAM;
penta and tetra side chains and D and L amino acids


draw a peptidoglycan disaccharide subunit + cleavage by lysozyme and
lysostaphin - correct answer ✔see slides


draw peptidoglycan cross-linking in E. coli (gram negative) - correct answer
✔see slides


draw peptidoglycan cross-linking in S. aureus (gram positive) - correct
answer ✔see slides


D form amino acids - correct answer ✔associated with NAM in
peptidoglycan, stereoisomers of L forms


L form amino acids - correct answer ✔encoded within the genome by DNA,
found naturally in biological proteins

,How are D forms made and why are they needed in peptide side chains? -
correct answer ✔from the environment- racemase racemizes L forms to
create D forms; proteases don't break down D forms, stabilize peptide side
chains


draw helical peptidoglycan structure - correct answer ✔see slides


What gives peptidoglycan rigidity? - correct answer ✔glycosidic bonds


What gives peptidoglycan flexibility? - correct answer ✔cross-linking
between side chains


How do we get things through peptidoglycan? - correct answer ✔porous,
things around 50 daltons can move through it; external to membrane 1. NAM
synthesized in the cytoplasm, linked to UDP 2. NAM linked to bactoprenol 3.
NAG is added to NAM 4. Bactoprenol flips NAM-NAG to periplasm 5.
Disaccharide added to existing chain, crosslinking occurs 6. Bactoprenol flips
back to cytoplasm


Draw entire cell wall + things getting through it - correct answer ✔see slides


effect of lysozyme - correct answer ✔enzyme found in tears, mucus, bodily
secretion; can cleave beta 1, 4 glycosidic bond between NAG and NAM
(backbone), leaves peptidoglycan in a weakened state, helps keep bacterial
populations in our body under control


effect of lysostaphin - correct answer ✔secreted by staphylococcus stimulin,
breaks pentaglycine interbridge (peptide linkages)

, beta-lactam antibiotics - correct answer ✔penicillin, cephalosporin,
carpabenem, monobactam


draw beta lactam ring structure of penicillin - correct answer ✔see slides


how penicillin works - correct answer ✔structurally similar to D-ala, D-ala;
transpeptidase binds to the antibiotic irrevirsibly so that it can't cross-link
peptidoglycan


What happens when the peptidoglycan cell wall is destroyed? - correct
answer ✔1. without an intact cell wall, the rod shape of an organism is
destroyed 2. In hypotonic conditions, water rushes in 3. internal pressure
causes cell lysis


how augmentin works - correct answer ✔combines clavulanic acid and
amoxicillin, beta-lactamases have a higher affinity for clavulonic acid because
it's smaller and easier to break the bonds, transpeptidase can bind to
amoxicillin the same way it binds to penicillin


methods of destroying beta lactam antibiotics - correct answer ✔efflux
pumps- pump beta lactam out of a cell; beta lactamases destroy beta lactam
ring structure


draw how beta-lactamases work in penicillin - correct answer ✔see slides


draw structures of clavulanic acid + amoxicillin - correct answer ✔see slides


Why is the cell wall a fantastic drug target? - correct answer ✔We don't have
peptidoglycan so we know that the antibiotics can specifically target bacteria

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