MICR 4423 EXAM STUDY QUESTIONS AND
CORRECT ANSWERS!!
Essential for biology and different between eukaryotes and bacteria
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
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
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
what is the function of EF-Tu? How does it help with translational fidelity?
The substrate of translation is Ef-Tu bound charged tRNA
what is the substrate of translation
o Exit, Peptidyl-binding site, and Accommodation 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
What are the three tRNA-associated sites in the bacterial ribosome, and what happens at each
, 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
What specifies the amino acid sequence of a protein?
o This is where the complete protein exits. It is in the 50S subunit (LSU)
What is the exit tunnel of a ribosome? Which subunit includes it?
o It charges tRNA with the corresponding amino acid. There are 20
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
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)
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-contains 4 fused rings
what is this
o Oxytetracycline, doxycycline, tigecycline, eravacycline
name 2 tetracyclines
o Block elongation/accommodation
o Prevents accommodation by destabilizing codon-anticodon interaction, thus codon-
CORRECT ANSWERS!!
Essential for biology and different between eukaryotes and bacteria
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
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
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
what is the function of EF-Tu? How does it help with translational fidelity?
The substrate of translation is Ef-Tu bound charged tRNA
what is the substrate of translation
o Exit, Peptidyl-binding site, and Accommodation 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
What are the three tRNA-associated sites in the bacterial ribosome, and what happens at each
, 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
What specifies the amino acid sequence of a protein?
o This is where the complete protein exits. It is in the 50S subunit (LSU)
What is the exit tunnel of a ribosome? Which subunit includes it?
o It charges tRNA with the corresponding amino acid. There are 20
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
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)
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-contains 4 fused rings
what is this
o Oxytetracycline, doxycycline, tigecycline, eravacycline
name 2 tetracyclines
o Block elongation/accommodation
o Prevents accommodation by destabilizing codon-anticodon interaction, thus codon-
