This set of Cytogenetics Multiple Choice Questions & Answers (MCQs) focuses on “Translation in Eukaryotes”.
1. What is the eukaryotic homologue for EF-G?
Explanation: The eukaryotic homologue for EF-G is EF2 while homologue for EF-Tu is EF1. These are the elongation factors that interact with the ribosome.
2. The eukaryotic initiation codon recognizes________
Explanation: The initiation of translation in eukaryotes is by the codon AUG that recognizes initiation tRNA or tRNAi that binds to methionine. While in prokaryotes it is by formyl met tRNA which binds to met and converts it to formyl met.
3. EF2 structurally mimics_______
c) Ribosomal subunit
Explanation: EF-2 should structurally mimic EF-1 such that it binds near the A site, and on GTP hydrolysis it can give the push to the tRNA at the A site of the ribosome to translocate it.
4. During translation RF1 recognizes the stop codon UGA and translation come to a halt as RF3 is called in.
Explanation: RF1 or release factor 1 is responsible for recognition of two stop codons- UAA and UAG, while RF2 can recognize the codon UGA.
5. What is the final factor in eukaryotes that releases the peptide and ribosome?
Explanation: The RF3 is responsible for cleavage of the peptide bond as well as for the release of the ribosomal subunits in eukaryotes.
6. A frame shift mutation can lead to alternate proteins.
Explanation: When there is a frame shift mutation in frame initiation codon and termination codon are transcribed. Thus, it can even lead to alternate initiation and alternate protein synthesis.
7. Which of the following will effectively cause normal translation from an initiation AUG, blocked by a strong AUG upstream?
a) Hairpin loop near the 1st AUG
b) No measure required
c) In frame stop codon between two AUGs
d) Deletion of the GAP between the two AUGs
Explanation: If there is in frame stop codon to 1st AUG there will be an open reading frame in between 1st AUG and stop codon and again another open reading frame from 2nd AUG. This will lead to effectively normal translation from the 2nd AUG.
8. In Eukaryotes the region between 1st AUG and 5’-G cap is known as ___________
Explanation: The UTR or untranslated region is the region near the 5’ end and 3’ end of the monocystronic eukaryotic mRNA that is not translated. From the AUG onwards s the Open reading frame or ORF which is translated till the stop codon.
9. The AU rich regions on the stem loop structure of IRE ____________
a) Promote translation
b) Promote degradation
c) Decrease translation
d) Decrease degradation
Explanation: The stem loop structures in the 3’ end in the UTR of the mRNA for transferring has some stem loop structures with the loop being rich in AU bases. These loops call in the protein responsible for degrading the mRNA increasing its turnover.
10. IRE-BP does not bind to _______________
b) Stem loop in 5’ end of Ferritin
c) Stem loop in 3’ end of Transferrin
d) AU rich regions in IRE
Explanation: IRES stands for Internal ribosomal entry site, which in no way is related to iron sensing. The AU rich regions in IRE are actually the step loop in 3’ end of transferring that binds to IRE-BP. Also, the stem loop in 5’ end of ferritin binds IRE-BP.
Sanfoundry Global Education & Learning Series – Cytogenetics.
To practice all areas of Cytogenetics, here is complete set of 1000+ Multiple Choice Questions and Answers.