MIC 541-Exam 4- Antimicrobials IV-1
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Cephems is a collective word for a group of antibiotics containing:
Cephalosporins and Cefemycins
Does Gram + have a periplasmic space?
Do Gram - have a periplastic space?
Do Gram - or Gram + have a periplastic space?
Describe the general composition of Peptidoglycan:
- n-acetyl glucosamine and n-muramic acid linked together
- amino acid chain extends from n-muramic acid
- The fourth amino acid (D-alanine) is linked to the 3rd Amino acid on the subsequent strand (DAP)
terminal step of cell wall synthsis which is th target of penicillin:
- cleaving of D-alaninin-D-alanine bond
- D-alanine cross links with DAP
After the D-alanine-D-alanine bond is cleaved in Peptidoglycan synthesis, how many amino acids are remaining?
Peptidoglycan is in out outside the plasma membrane?
Penicillin and cephalosporins attack what?
The cross linking of the peptidoglycan
Penicillins and cephalosporins attack what step (in terms of synthesis order)?
What are the three very general steps in creating Peptidoglycan?
- 1.) Synthesis of the individual component molecules
- 2.) Transport of these molecules out of the cell
- 3.) Assembly of these molecules into peptidoglycan
Terminal step of cell wall synthesis is attacked by Penicillina nd cephalosporins
Why are B-lactams important?
- Most heavily perscribed antibiotic
- b/c they are the most safe and efficaious antibiotics
How were B-lactams named?
After the B-lactam ring that they all contain
What bond is the basis for efficacy in B-lactams?
B-lactam bond (found between the N and C=0 in the B-lactam ring)
Describe the B-lactam ring?
What defense do some bacteria have against B-lactams?
What is the target of B-lactamases?
In what way, as discussed in class, were chemist able to protect teh B-lactam bond against B-lactamases?
Creat a substituent that wraps around and inhibits attack
What portion of a B-lactam antibiotic is available for chemical manipulation?
The substituent arm extending from the B-lacatam ring on the opposite side as the thiazolidine ring
What does PBP stand for?
Penicillin binding protein
What is a Penicillin binding protein?
An enzyme that cross links and modifies peptidoglycan
What enzymes ar responsible for binding D-alanine-D-alanine and creating crosslinking between strands of Peptidoglycan?
- Penicillin binding proteins (PBPS)
- B-lactam antibiotics are analogs of what?
How do B-lactams inactivate PBPs?
Binding to PBPs in place of D-alanine-D-alanine
What is the significance of multiple PBPs, in terms of antibiotics?
multiple pathways to attack PBPs = multiple pathways to kill bacteria
Where are PBPs located?
in the cytoplasmic membrane
What is general action of B-lactams?
They inhibit cell wall synthesis
How many essential PBPs have been identified in E. coli?
Drugs that attack PBP1 cause:
The inhibition of which E. coli PBP causes lysis ?
Antibiotics that effect PBP3 cause what?
The inhibition of which E. coli PBP causes Filementation?
Antibiotics that effect PBP2 cause:
Change to oval shape
The inhibition of which E.coli PBP causes the shape to change to oval?
Why is PBP2 a good target?
Because there are only a few molecules of PBP2 in the cell
When were penicillins discovered?
Who discovered Penicillins?
What bacteria was inhibited in the discovery of Penicillin?
What date (approx.) was Penicillin developed into a drug?
Who developed Penicillin into a drug?
Semisythetic antibiotics were first made when?
Penicillin is the best choice antibiotic under what conditions?
- The patient ins not allergic
- the pathogen is susceptible
You should always consider what antibiotic first?
What are the only two reasons to not use Penicillins?
- The pathogen is resistant
- The patient is allergic
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