Question

30. Which of the following statements reg wing statements regarding the Alpha subunit of RNA polymerase is INCORRECT? A. Can bind an UP element B. Can interact with positive activator proteins C. Binds to the Beta and Beta' subunits D. Has distinct N-terminal and C-terminal domains E. Has 3' to 5' exonuclease activity 31. Which of the following statements regarding the mediator complex is arding the mediator complex is CORRECT? A. Mediator interacts with auxiliary activator prou interacts with auxiliary activator proteins to help recruit RNA Pol II. B. The mediator complexi The mediator complex is a multisubunit ribonucleoprotein that contains several SnRNAs. c. Mediator facilitates loading of the capping enzymes. D. Mediator loads onto the phosphorylated CTD of Pol II during transcription elongation. E. Mediator activates the cleavage of mRNA in preparation for poly-adenylation. 32. The eukaryotic pre-mRNA shown below can undergo alternative splicing. Potential exon sequences are boxed and designated A, B, C, etc. Which of the following mRNA isoforms IS NOT possible given the mechanism of splicing? CAHBCHODE-3 A. S-CA I BICI DTE-3 B. SCATE C. SCA I DIBE-3 D. SAT BIDE3 E. 5-A BIE-3

can you guys please give me the correct answers and explain why?

Answer 1

30. Answer: Statement E is incorrect.

Explanation: RNA polymerase doesn't show any exonuclease activity.

The rest of the statements are correct.

31. Answer: Statement A is correct.

Explanation: Mediator interacts with auxiliary factors such as HMGA 1, SAGA, etc and helps to form the pre-initiation complex as well as recruit RNA Pol II. Thus helps to regulate gene expression.

The other statements are incorrect.

32. Answer: C

Explanation: In alternative splicing, in healthy cells, the exons are not scrambled like the case in "isoform C". They usually joined in the correct sequence. i.e. "exon A" before "exon B", "exon C" before "exon D" etc.. lIke it happened in all the other given spliced isoforms.

But in "C isoform" the exons are scrambled. i.e. "exon D" appeared before "exon B".

This type of scenario usually occurs rarely in neoplastic cells or in circular RNAs (where 3' and 5' ends are joined) but not in the general mechanism of alternative splicing.