MICR 4423 EXAM 3 QUESTIONS AND ANSWERS
Essential for biology/and bacterial viability and different between eukaryotes and
bacteria - Answers - Why are the bacterial ribosome and RNA polymerase good targets
for antibiotic action? There are 2 criteria they meet
Elongation factor G (EF-G) uses energy stored in GTP to catalyze movement of transfer
RNAs and messenger RNA in the ribosome during the translocation step of prokaryotic
protein synthesis - Answers - What is the function of ef-g
70 S with 50S LSU and 30S SSU. SSU contains 16S rRNA and proteins. LSU contains
23S and 5s rRNA and proteins. EF-Tu, initiation elongation and release factors, EF-G,
mRNA - Answers - What are the components needed for bacterial translation? Include
ribosomal subunits and chaperones.
o Binds to all charged tRNAs as a chaperone, escorts them to A site of a ribosome
(creates codon/anticodon match)
o If the tRNA stays long enough because the anti-codon-codon match is correct, then
GTP is spent by EF-Tu and it can leave, movin on from accommodation to peptidyl
transfer step - Answers - what is the function of EF-Tu? How does it help with
translational fidelity?
The substrate of translation is Ef-Tu bound charged tRNA - Answers - what is the
substrate of translation
o Exit, Peptidyl-binding site, and Aminoacyl binding site. The Ef-tu bound charged tRNA
enters at the aminoacyl binding site. The peptidyl-binding site is the place with the
tRNA-bound peptide chain expands, and the exit site is where the empty/uncharged
tRNA is released - Answers - What are the three tRNA-associated sites in the bacterial
ribosome, and what happens at each
- Answers - Be able to label a diagram of the bacterial ribosome, with the A, P, and E
sites, the exit tunnel, tRNAs, the ribosomal subunits, EF-Tu and EF-G.
o Codon sequence of the mRNA - Answers - What specifies the amino acid sequence
of a protein?
o Block elongation/accommodation
o Prevents accommodation by destabilizing codon-anticodon interaction, thus codon-
anticodon matches are not found
o Interacts with 16s rRNA (30S subunit) and codon at A site - Answers - 1. How do
tetracyclines act as antibiotics? Be specific about where they bind, what step they block
and how it is blocked.
o Blocks accommodation
, o Bind 30 S subunit at A site (like tetracyclines)
o Stabilizes codon-anticodon mismatch, dramatically increasing the rate of
misincorporation. This leads to misfolded proteins which are rapidly bactericidal -
Answers - 1. How do aminoglycosides act as antibiotics? Be specific about where they
bind, what step they affect and how it is affected.
goes from 1 in 10,000 AA mistakes to 1 in 100 AA mistakes - Answers - how do
aminoglycosides affect the rate of mismatch
o Tobramycin
o Amikacin
o Neomycin - Answers - Name two aminoglycosides.
aminoglycosides - Answers - what is this
oxazolidinone->noooo strand - Answers - what is this
o Radezolid
o Torezolid or tedizolid - Answers - Name an oxazolidinone
o It is effective against ABX-resistant G+ pathogens such as MRSA and it is completely
synthetic - Answers - What makes oxazolidinones different from most of the other
antibiotics we discussed
o This is where the complete protein exits. It is in the 50S subunit (LSU) - Answers -
What is the exit tunnel of a ribosome? Which subunit includes it?
o It charges tRNA with the corresponding amino acid. There are 20 - Answers - 1. What
is the function of an aminoacyl-tRNA synthetase? How many are there?
o It binds isoleucyl tRNA synthetase at the active site, preventing the formation of a
charged isoleucine-tRNA - Answers - 1. How does mupirocin act as an antibiotic? Be
specific about what it targets and how it affects that target.
Kasugamycin is a bacterial translation inhibitor. Kasugamycin binds at the P site of the
30s Subunit and competes for binding with the initiator tRNA (fMet = formyl methionine)
for the spot. This blocks translation initiation and the 50s subunit does not attach. This
leaves the mRNA naked and with no full ribosome. (Protein synthesis inhibitor) -
Answers - 1. How does kasugamycin act as an antibiotic? Be specific about what it
binds to, what step it blocks and how it blocks it.
tetracycline - Answers - what is this
o Oxytetracycline, doxycycline, tigecycline, eravacycline - Answers - name 2
tetracyclines
Essential for biology/and bacterial viability and different between eukaryotes and
bacteria - Answers - Why are the bacterial ribosome and RNA polymerase good targets
for antibiotic action? There are 2 criteria they meet
Elongation factor G (EF-G) uses energy stored in GTP to catalyze movement of transfer
RNAs and messenger RNA in the ribosome during the translocation step of prokaryotic
protein synthesis - Answers - What is the function of ef-g
70 S with 50S LSU and 30S SSU. SSU contains 16S rRNA and proteins. LSU contains
23S and 5s rRNA and proteins. EF-Tu, initiation elongation and release factors, EF-G,
mRNA - Answers - What are the components needed for bacterial translation? Include
ribosomal subunits and chaperones.
o Binds to all charged tRNAs as a chaperone, escorts them to A site of a ribosome
(creates codon/anticodon match)
o If the tRNA stays long enough because the anti-codon-codon match is correct, then
GTP is spent by EF-Tu and it can leave, movin on from accommodation to peptidyl
transfer step - Answers - what is the function of EF-Tu? How does it help with
translational fidelity?
The substrate of translation is Ef-Tu bound charged tRNA - Answers - what is the
substrate of translation
o Exit, Peptidyl-binding site, and Aminoacyl binding site. The Ef-tu bound charged tRNA
enters at the aminoacyl binding site. The peptidyl-binding site is the place with the
tRNA-bound peptide chain expands, and the exit site is where the empty/uncharged
tRNA is released - Answers - What are the three tRNA-associated sites in the bacterial
ribosome, and what happens at each
- Answers - Be able to label a diagram of the bacterial ribosome, with the A, P, and E
sites, the exit tunnel, tRNAs, the ribosomal subunits, EF-Tu and EF-G.
o Codon sequence of the mRNA - Answers - What specifies the amino acid sequence
of a protein?
o Block elongation/accommodation
o Prevents accommodation by destabilizing codon-anticodon interaction, thus codon-
anticodon matches are not found
o Interacts with 16s rRNA (30S subunit) and codon at A site - Answers - 1. How do
tetracyclines act as antibiotics? Be specific about where they bind, what step they block
and how it is blocked.
o Blocks accommodation
, o Bind 30 S subunit at A site (like tetracyclines)
o Stabilizes codon-anticodon mismatch, dramatically increasing the rate of
misincorporation. This leads to misfolded proteins which are rapidly bactericidal -
Answers - 1. How do aminoglycosides act as antibiotics? Be specific about where they
bind, what step they affect and how it is affected.
goes from 1 in 10,000 AA mistakes to 1 in 100 AA mistakes - Answers - how do
aminoglycosides affect the rate of mismatch
o Tobramycin
o Amikacin
o Neomycin - Answers - Name two aminoglycosides.
aminoglycosides - Answers - what is this
oxazolidinone->noooo strand - Answers - what is this
o Radezolid
o Torezolid or tedizolid - Answers - Name an oxazolidinone
o It is effective against ABX-resistant G+ pathogens such as MRSA and it is completely
synthetic - Answers - What makes oxazolidinones different from most of the other
antibiotics we discussed
o This is where the complete protein exits. It is in the 50S subunit (LSU) - Answers -
What is the exit tunnel of a ribosome? Which subunit includes it?
o It charges tRNA with the corresponding amino acid. There are 20 - Answers - 1. What
is the function of an aminoacyl-tRNA synthetase? How many are there?
o It binds isoleucyl tRNA synthetase at the active site, preventing the formation of a
charged isoleucine-tRNA - Answers - 1. How does mupirocin act as an antibiotic? Be
specific about what it targets and how it affects that target.
Kasugamycin is a bacterial translation inhibitor. Kasugamycin binds at the P site of the
30s Subunit and competes for binding with the initiator tRNA (fMet = formyl methionine)
for the spot. This blocks translation initiation and the 50s subunit does not attach. This
leaves the mRNA naked and with no full ribosome. (Protein synthesis inhibitor) -
Answers - 1. How does kasugamycin act as an antibiotic? Be specific about what it
binds to, what step it blocks and how it blocks it.
tetracycline - Answers - what is this
o Oxytetracycline, doxycycline, tigecycline, eravacycline - Answers - name 2
tetracyclines
