UCI - Bio 99 - Inlay - Lecture 6 Questions With Complete
Solutions
A mutation if EF-G will halt elongation at which step?
A. aminoacyl-tRNA entry
B. Accomodation
C. Peptidyl-transferase reaction
D. Translocation Correct Answers B
Case 1: no stop codon Correct Answers non-stop mRNA decay
- ribosome translates AAA to produce long string of poly-lysine,
which is recognized by Ski7, which dissociates the ribosomes
and recruits exosomes/proteases to eat mRNA and protein
Case 2: premature stop codon (nonsense mutation) Correct
Answers nonsense-mediated mRNA decay
- exon junctions are marked by EJC
- in mRNAs that are premature, some EJCs remain bound to
mRNA after ribosome dissociates
- Upf1 and Upf2 recognize EJCs and recruit decapping enzyme
to 5' cap
EF-G Correct Answers bound by GTP; pulls ribosome over one
codon and fixes hybrid state
EF-Ts Correct Answers regenerates GTP on EF-Tu
EF-Tu Correct Answers bound by GTP; escorts new aminoacyl-
tRNA into A site and protects it from hydrolysis
, GTP hydrolysis powers accomodation and translocation, what
provides the energy for the peptidyl-transferase reaction?
A. Forming peptide bond
B. ATP hydrolysis
C. Severing aminoacyl-tRNA bond
D. Conformation change to ribosome Correct Answers C
How does Upf1 and Upf2 cause degradation of mRNAs with
premature stop codons?
A. By cleaving the 5' cap of mRNA
B. By recruiting a decapping enzyme
C. By recruiting an endonuclease to chew up mRNA
D. By recruiting proteases to chew up protein Correct Answers
B
hybrid state Correct Answers state where growing polypeptide
is now attached to the A site tRNA
Puromycin can act as a substrate for the peptidyl-transferase
reaction. What other non-aminoacyl tRNA can do this?
A. RF-1
B. RF-3
C. RRF
D. EF-G Correct Answers A
RF Correct Answers protein factor that recognizes a stop codon
RF-1 Correct Answers UAG, UAA stop codons
Solutions
A mutation if EF-G will halt elongation at which step?
A. aminoacyl-tRNA entry
B. Accomodation
C. Peptidyl-transferase reaction
D. Translocation Correct Answers B
Case 1: no stop codon Correct Answers non-stop mRNA decay
- ribosome translates AAA to produce long string of poly-lysine,
which is recognized by Ski7, which dissociates the ribosomes
and recruits exosomes/proteases to eat mRNA and protein
Case 2: premature stop codon (nonsense mutation) Correct
Answers nonsense-mediated mRNA decay
- exon junctions are marked by EJC
- in mRNAs that are premature, some EJCs remain bound to
mRNA after ribosome dissociates
- Upf1 and Upf2 recognize EJCs and recruit decapping enzyme
to 5' cap
EF-G Correct Answers bound by GTP; pulls ribosome over one
codon and fixes hybrid state
EF-Ts Correct Answers regenerates GTP on EF-Tu
EF-Tu Correct Answers bound by GTP; escorts new aminoacyl-
tRNA into A site and protects it from hydrolysis
, GTP hydrolysis powers accomodation and translocation, what
provides the energy for the peptidyl-transferase reaction?
A. Forming peptide bond
B. ATP hydrolysis
C. Severing aminoacyl-tRNA bond
D. Conformation change to ribosome Correct Answers C
How does Upf1 and Upf2 cause degradation of mRNAs with
premature stop codons?
A. By cleaving the 5' cap of mRNA
B. By recruiting a decapping enzyme
C. By recruiting an endonuclease to chew up mRNA
D. By recruiting proteases to chew up protein Correct Answers
B
hybrid state Correct Answers state where growing polypeptide
is now attached to the A site tRNA
Puromycin can act as a substrate for the peptidyl-transferase
reaction. What other non-aminoacyl tRNA can do this?
A. RF-1
B. RF-3
C. RRF
D. EF-G Correct Answers A
RF Correct Answers protein factor that recognizes a stop codon
RF-1 Correct Answers UAG, UAA stop codons
