MCB 101 FINAL EXAM QUESTIONS WITH VERIFIED
ANSWERS
Antimicrobial Agents - Answers - Kill microorganisms or inhibit their growth, ideally
without harming human, animal or plant host
*key trait= selective toxicity*
What are antibiotics made by? - Answers - Fungus or bacterium
Antibiotics role - Answers - Kill or inhibit growth of microorganisms
Penicillin - Answers - Antibiotic
-discovered by Fleming in 1929
-produced by a mold (Penicillium notatum)
Streptomycin - Answers - Antibiotic
-found by Schatz & Waksman 1943
-produced by a gram + soil bacterium
Chemotherapeutic Agents - Answers - Do not occur naturally
-synthesized in a lab
-kill or inhibit microorganisms
Salvarsan - Answers - Chemo. Agent
-developed by Ehrlich 1908
-used against syphilis bacteria and Trypanosomes
Semi-Synthetic Agents - Answers - Occur naturally, but are modified in lab
-most antibiotics are semi-synthetic
-exs: amoxicillin, methicillin
Penicillins, Cephalosporins, Vancomycin, Bacitracin: mechanism of action - Answers -
Peptidoglycan synthesis inhibitors block bacterial cell wall formation.
-Penicillins stop formation of bonds that cross-like the peptide chains
Penicillins, Cephalosporins, Vancomycin, Bacitracin: basis of selective toxicity -
Answers - Animal cells don't have cell walls
Streptomycin, Tetracycline, Erythromycin: mechanism of action - Answers - These
antibiotics bind to 70S ribosomes and inhibit bacterial protein synthesis
Streptomycin, Tetracycline, Erythromycin: basis of selective toxicity - Answers - Animal
cells have 80S ribosomes
, Polymyxin: mechanism of action - Answers - Detergent-like agent that disrupts bacterial
cytoplasmic membranes.
-Specific binding to LPS makes it especially effective against Gram - bacteria
Polymyxin: basis of selective toxicity - Answers - Animal cell membranes are stronger
than bacterial cell membranes because they contain sterols
Rifampin: mechanism of action - Answers - Binds to bacterial RNA polymerase and
inhibits transctiption (mRNA synthesis)
Rifampin: basis of selective toxicity - Answers - Eukaryotic RNA polymerases are quite
different from bacterial RNA polymerase
Different bacteria have different _________ to ____________ - Answers -
Susceptibility; specific antibiotics
Disc Diffusion Test - Answers - Used to determine what antibiotics are best for inhibiting
a specific strain of bacteria, look for a zone of inhibition around a disc that contains
antibiotic
Minimum Inhibitory Concentration (MIC) Test - Answers - Determine minimum
concentration of antibiotic needed to inhibit the growth of a microorganism (doesn't kill)
Why are eukaryotic microorganisms harder to treat? - Answers - They are biochemically
and structurally more similar to the host cell; antibiotics only kill harmful microbe not the
actual host
Bacteriocidal - Answers - Destroys the microorganism -> cell death
-destroys cell wall (penicillin) and cell membrane (polymixin)
Bacteriostatic - Answers - Doesn't kill, just slows the growth of microorganism
-allows time for body's own immune system to fight the infection
Broad Spectrum Antibiotics - Answers - Effective against many diff types and species of
bacteria (gram +/-)
-Streptomycin
Narrow Spectrum Antibiotics - Answers - Only effective against a small number of
bacteria either gram - or gram +
-Penicillin
Kirby-Bauer Test - Answers - Measures the zone of inhibition
Minimum Bacteriocidal Concentration (MBC) - Answers - Lowest concentration that will
KILL the microorganism
ANSWERS
Antimicrobial Agents - Answers - Kill microorganisms or inhibit their growth, ideally
without harming human, animal or plant host
*key trait= selective toxicity*
What are antibiotics made by? - Answers - Fungus or bacterium
Antibiotics role - Answers - Kill or inhibit growth of microorganisms
Penicillin - Answers - Antibiotic
-discovered by Fleming in 1929
-produced by a mold (Penicillium notatum)
Streptomycin - Answers - Antibiotic
-found by Schatz & Waksman 1943
-produced by a gram + soil bacterium
Chemotherapeutic Agents - Answers - Do not occur naturally
-synthesized in a lab
-kill or inhibit microorganisms
Salvarsan - Answers - Chemo. Agent
-developed by Ehrlich 1908
-used against syphilis bacteria and Trypanosomes
Semi-Synthetic Agents - Answers - Occur naturally, but are modified in lab
-most antibiotics are semi-synthetic
-exs: amoxicillin, methicillin
Penicillins, Cephalosporins, Vancomycin, Bacitracin: mechanism of action - Answers -
Peptidoglycan synthesis inhibitors block bacterial cell wall formation.
-Penicillins stop formation of bonds that cross-like the peptide chains
Penicillins, Cephalosporins, Vancomycin, Bacitracin: basis of selective toxicity -
Answers - Animal cells don't have cell walls
Streptomycin, Tetracycline, Erythromycin: mechanism of action - Answers - These
antibiotics bind to 70S ribosomes and inhibit bacterial protein synthesis
Streptomycin, Tetracycline, Erythromycin: basis of selective toxicity - Answers - Animal
cells have 80S ribosomes
, Polymyxin: mechanism of action - Answers - Detergent-like agent that disrupts bacterial
cytoplasmic membranes.
-Specific binding to LPS makes it especially effective against Gram - bacteria
Polymyxin: basis of selective toxicity - Answers - Animal cell membranes are stronger
than bacterial cell membranes because they contain sterols
Rifampin: mechanism of action - Answers - Binds to bacterial RNA polymerase and
inhibits transctiption (mRNA synthesis)
Rifampin: basis of selective toxicity - Answers - Eukaryotic RNA polymerases are quite
different from bacterial RNA polymerase
Different bacteria have different _________ to ____________ - Answers -
Susceptibility; specific antibiotics
Disc Diffusion Test - Answers - Used to determine what antibiotics are best for inhibiting
a specific strain of bacteria, look for a zone of inhibition around a disc that contains
antibiotic
Minimum Inhibitory Concentration (MIC) Test - Answers - Determine minimum
concentration of antibiotic needed to inhibit the growth of a microorganism (doesn't kill)
Why are eukaryotic microorganisms harder to treat? - Answers - They are biochemically
and structurally more similar to the host cell; antibiotics only kill harmful microbe not the
actual host
Bacteriocidal - Answers - Destroys the microorganism -> cell death
-destroys cell wall (penicillin) and cell membrane (polymixin)
Bacteriostatic - Answers - Doesn't kill, just slows the growth of microorganism
-allows time for body's own immune system to fight the infection
Broad Spectrum Antibiotics - Answers - Effective against many diff types and species of
bacteria (gram +/-)
-Streptomycin
Narrow Spectrum Antibiotics - Answers - Only effective against a small number of
bacteria either gram - or gram +
-Penicillin
Kirby-Bauer Test - Answers - Measures the zone of inhibition
Minimum Bacteriocidal Concentration (MBC) - Answers - Lowest concentration that will
KILL the microorganism
