BIO 150 LECTURE EXAM 3 Question and
answers verified to pass (28 pgs)
Contrast narrow spectrum and broad spectrum antimicrobials. - correct
answer ✔Some antibiotics cure a narrow or small range of things and some
cure a broad, large range of things.
Explain the concept of selective toxicity. - correct answer ✔An effective
antimicrobial agent that must be more toxic to a pathogen than a pathogens
host; Other words you dont want to take a medicine that will affect our healthy
cells as well as the infected ones..only the bad ones
List the five target sites for antimicrobials. - correct answer ✔1. *cell wall
inhibitors* inhibition of cell wall synthesis (making peptidoglycan which is
important in growth because cell has to get larger before it divides),
2. *DNA/RNA* - inhibition of nucleic acid (RNA and DNA) structure and
function by affecting the enzymes polymerase. NOT SELECTIVLEY TOXIC
3. *Protein synthesis inhibitors acting on ribosomes* - inhibition of protein
synthesis (target ribsomes),HIGHLY SELECTIVE FOR RIBOSOME SHAPE
4. *cell membrane* - interference with cell membrane (phospholipids)
structure/function LOW TOXICITY-we have phospolipids
5. *Folic Acid Synthesis in the Cytoplasm* - inhibition of folic acid synthesis
(we don't make it which means it a good spot for selective toxicity because
bacteria DO make it HIGHLY SELECTIVE-flic acid pathway
Identify which categories of drugs are most selective and why. - correct
answer ✔tetracyclines because they inhibit protein synthesis that occurs in
bacterial cells and human cells
Understand how some
,antimicrobials prevent bacteria growth that inhibit cell wall synthesis. - correct
answer ✔Inhibits the synthesis of peptidoglycan- cell wall is not properly
formed and cell burst
Beta-Lactams can have Betalactamase that breaks down the beta lactam ring
which make agents ineffective.
More effective on Gram + cells , HIGHLY SELECTIVLEY TOXIC FOR
PEPTIDOGYCAN
List the target site for penicillin. - correct answer ✔Targets peptidoglycan -
they can still make it but its not formed correctly and it leads to lysis.
- prevents the synthesis of complete cell walls leading to lysis of the cell
- acts only on growing bacteria that are synthesizing new peptidoglycan.
Identify how antimicrobials that inhibit nucleic acid structure and function work.
- correct answer ✔Enzymes are effected, it blocks DNA replication and RNA
transcription synthesizing proteins
NOT SELECTIVELY TOXIC as we have these enzymes.
DNA and RNA polymerase-raframpin-Treats TB
List two antimicrobials that inhibit nucleic acid structure and function. - correct
answer ✔Quinolones-block DNA replication Inhibits unwinding
Rifampin-blocks transcription DNA- RNA by blocking synthesis of mRna by
inhibiting RNA polymerase.
, Understand how polymyxins inhibit bacterial cells. - correct answer ✔(p 269)
Interfere with cell membrane structure (phospholipid bilayer) and function.
Interact with hydrophobic tails.
More effective for gram- cells because they have the extra phospholipid
bilayer.
NOT selectively toxic because cell membranes are made up of phospholipids
(as are eukaryotic cells). Ex: polysporin, bacitracin, neosporin, ointments,
topical and not going to bring into body. Not given orally because 1)they're not
absorbed well by the intestine and 2) can be toxic to our own cells because
we have phospholipids in our cells too.
Used for skin infections and a middle ear infections.
Identify the microbial category that streptomycin, tetracyclines and macrolides
fall into.
a. How do these affect bacteria (general)? - correct answer ✔Streptomycin &
tetracycline block the small ribosomal subunit.
Macrolides(Z-pack) interact with the large ribosomal subunit
Tetracycline inhibit protein synthesis by blocking the binding sites so tRna
cannot bind where needed so cell cannot make proteins which cells need in
order to replicate.
Selectively toxic because ribosomal subunits are different in prokaryotes vs
eukaryotes.
answers verified to pass (28 pgs)
Contrast narrow spectrum and broad spectrum antimicrobials. - correct
answer ✔Some antibiotics cure a narrow or small range of things and some
cure a broad, large range of things.
Explain the concept of selective toxicity. - correct answer ✔An effective
antimicrobial agent that must be more toxic to a pathogen than a pathogens
host; Other words you dont want to take a medicine that will affect our healthy
cells as well as the infected ones..only the bad ones
List the five target sites for antimicrobials. - correct answer ✔1. *cell wall
inhibitors* inhibition of cell wall synthesis (making peptidoglycan which is
important in growth because cell has to get larger before it divides),
2. *DNA/RNA* - inhibition of nucleic acid (RNA and DNA) structure and
function by affecting the enzymes polymerase. NOT SELECTIVLEY TOXIC
3. *Protein synthesis inhibitors acting on ribosomes* - inhibition of protein
synthesis (target ribsomes),HIGHLY SELECTIVE FOR RIBOSOME SHAPE
4. *cell membrane* - interference with cell membrane (phospholipids)
structure/function LOW TOXICITY-we have phospolipids
5. *Folic Acid Synthesis in the Cytoplasm* - inhibition of folic acid synthesis
(we don't make it which means it a good spot for selective toxicity because
bacteria DO make it HIGHLY SELECTIVE-flic acid pathway
Identify which categories of drugs are most selective and why. - correct
answer ✔tetracyclines because they inhibit protein synthesis that occurs in
bacterial cells and human cells
Understand how some
,antimicrobials prevent bacteria growth that inhibit cell wall synthesis. - correct
answer ✔Inhibits the synthesis of peptidoglycan- cell wall is not properly
formed and cell burst
Beta-Lactams can have Betalactamase that breaks down the beta lactam ring
which make agents ineffective.
More effective on Gram + cells , HIGHLY SELECTIVLEY TOXIC FOR
PEPTIDOGYCAN
List the target site for penicillin. - correct answer ✔Targets peptidoglycan -
they can still make it but its not formed correctly and it leads to lysis.
- prevents the synthesis of complete cell walls leading to lysis of the cell
- acts only on growing bacteria that are synthesizing new peptidoglycan.
Identify how antimicrobials that inhibit nucleic acid structure and function work.
- correct answer ✔Enzymes are effected, it blocks DNA replication and RNA
transcription synthesizing proteins
NOT SELECTIVELY TOXIC as we have these enzymes.
DNA and RNA polymerase-raframpin-Treats TB
List two antimicrobials that inhibit nucleic acid structure and function. - correct
answer ✔Quinolones-block DNA replication Inhibits unwinding
Rifampin-blocks transcription DNA- RNA by blocking synthesis of mRna by
inhibiting RNA polymerase.
, Understand how polymyxins inhibit bacterial cells. - correct answer ✔(p 269)
Interfere with cell membrane structure (phospholipid bilayer) and function.
Interact with hydrophobic tails.
More effective for gram- cells because they have the extra phospholipid
bilayer.
NOT selectively toxic because cell membranes are made up of phospholipids
(as are eukaryotic cells). Ex: polysporin, bacitracin, neosporin, ointments,
topical and not going to bring into body. Not given orally because 1)they're not
absorbed well by the intestine and 2) can be toxic to our own cells because
we have phospholipids in our cells too.
Used for skin infections and a middle ear infections.
Identify the microbial category that streptomycin, tetracyclines and macrolides
fall into.
a. How do these affect bacteria (general)? - correct answer ✔Streptomycin &
tetracycline block the small ribosomal subunit.
Macrolides(Z-pack) interact with the large ribosomal subunit
Tetracycline inhibit protein synthesis by blocking the binding sites so tRna
cannot bind where needed so cell cannot make proteins which cells need in
order to replicate.
Selectively toxic because ribosomal subunits are different in prokaryotes vs
eukaryotes.
