1. Aminoglycosides can kill_______________
a) Broad spectrum of prokaryotes
b) Only gram positive bacteria
c) Only anerobic gram positive bacteria
d) Only aerobic gram negative bacteria
Explanation: Aminoglycosides are the group of antibiotic that can kill gram negative bacteria which are aerobic. Some of such antibiotics are Streptomycin, Paramomycin etc.
2. In evolutionary history which of the following rose 1st?
a) DNA
b) RNA
c) Protein
d) Oxygenic mode of respiration
Explanation: RNA was the 1st to arise which served both as information storage and as enzyme namely ribozyme. Later it transferred the activities to more specific molecules namely DNA and protein respectively
3. The 16S rRNA binds the mRNA in its ___________ region.
a) Body
b) Head
c) Neck
d) Flap
Explanation: The 3’-OH end of the 16S rRNA is located in the neck region of the rRNA. Near it is the Shine and Dalgarno sequence that binds the mRNA.
4. _____________ treated ribosomes will be able to carry out elongation and termination of previously initiated translation, but can’t initiate any new translation.
a) Streptomycin
b) Rifampicin
c) Tetracyclin
d) Colicin E3
Explanation: Colicin e# effects initiation at the Shine and Dalgarno sequence, however, it has no effect on elongation of termination. Thus, it will prevent new initiation but will not halt already translating ribosomes
5. IF1 helps in correct placement of the initiation tRNA. How does it do so?
a) By guiding it to P site
b) By binding to A site
c) By dissociating the ribosomal complex
d) By binding to the P site
Explanation: IF1 binds to the A site of the 30S subunit so that the 1st aminoacyl-tRNA can’t sit at the A site. It then sits on the P site i.e. correct position.
6. Which initiation factor prevents association of ribosome when not bound to mRNA?
a) IF1
b) IF2
c) IF3
d) IF4
Explanation: The IF3 binds to the 30S subunit and prevents association of 30S and 50S subunit when the ribosome is not bound to mRNA. It also helps in binding t the mRNA
7. If you see a GTP bound IF2 it is _________
a) Before initiation
b) During initiation
c) After initiation
d) Not related to an initiation
Explanation: IF2 guides the 1st tRNA to the P site of the ribosome. Then it is GTP bound. When properly placed the GTP hydrolyses to GDP and the IF2 is released.
8. Which proteins perform the function of preventing reassociation of ribosomal subunits, when they finish one translation, in eukaryotes?
a) eIF1 and eIF3
b) eIF3 and eIF6
c) eIF2 and eIF4
d) eIF3 and eIF5
Explanation: eIF1 is a multi protein complex with eight subunits; this along with eIF6 prevents the reassociation of the subunits of ribosome after translation of one protein is complete.
9. What is used to regulate translation initiation in eukaryotes?
a) Turnover of mRNA
b) Ubiquitination of ribosome
c) Phosphorylation of IF2
d) Methylation of IF1a
Explanation: Phosphorylation of IF2 prevents it from binding to f-MettRNA-f-Met, thus it prevents initiation of translation by IF2 bringing the 1st amino acid
10. Which of the bases are important in detecting whether the AUG should be the start site for eukaryotic initiation?
a) -2 and +3
b) -4 and +3
c) -3 and +4
d) -1 and +4
Explanation: The consensus sequence CC(A/G)CCAUGG was discovered by Kozak, where the purine in -3 and +4 position is significant in determining which AUG should serve as initiation site.