Cytogenetics Mock Test 1

10%

Question 1 of 10

1. A ssRNA shows inverted tandem repeat. What would be its secondary structure?

Linear

Crucifix

Stem-loop structure

Hair pin

Question 1 of 10

Question 2 of 10

2. The catalytic activity resides in which subunit of RNA polymerase?

α (37 kDa)

β (151 kDa)

σ70 (70 kDa)

β′ (156 kDa)

Question 2 of 10

Question 3 of 10

3. In an experiment you add increasing amount of sigma factor to a mixture of DNA fragment and core polymerase in vitro. You also add [¹⁴C]ATP and [γ-³²P]ATP in the mixture and check the rate of incorporation. Results show that the incorporation of both of this labels increase on adding more sigma factor. What will you conclude from your observation?

Sigma increases initiation and elongation rate

Sigma causes faster elongation

Sigma increases initiation of transcription rate

Sigma confers specificity and increases transcription rate

Question 3 of 10

Question 4 of 10

4. While studying the transcripts in vitro you observe that other than the longer transcripts there are some short stretches of RNA oligomer produced as well. You repeat the experiment several times but these oligomers seem to persist. What is the possible explanation?

Procedural error

They are the un-ligated oligomers of lagging strand

Experimental artifact

Normal occurrence

Question 4 of 10

Question 5 of 10

5. Which is the most processive of prokaryotic DNA polymerases?

pol III

klenow fragment

pol I

pol II

Question 5 of 10

Question 6 of 10

6. Rho dependent termination mechanism doesn’t reguire____________

G-C rich stem

Stem loop structure

Sigma factor

ATP

Question 6 of 10

Question 7 of 10

7. Which of the Ars operon regulation site is actually preventing RNA polymerase from binding and producing the Ara genes BAD?

Question 7 of 10

Question 8 of 10

8. In a mero-diploid you have one I- and one I+ Repressor gene in the two lac operons. I+ is wild type while I- is a mutant which produces a repressor that doesn’t bind. What would be the functionality of the diploid?

May or may not function

Function normally

Will have impaired functioning

Will be non-functional

Question 8 of 10

Question 9 of 10

9. Which of these Lac operon mero- diploid will be constitutively turned on? Considering the terms has their usual meaning.

I^s + P + O⁺ + Z⁺ + Y⁺ + A⁺ / I⁺ + P+ O⁺ + Z⁺ + Y⁺ + A⁺

I⁺ + P + O^C + Z⁺ + Y⁺ + A⁺ / I⁺ + P+ O⁺ + Z⁺ + Y⁺ + A⁺

I⁺ + P + O⁺ + Z⁺ + Y⁺ + A⁺ / I⁺ + P+ O⁺ + Z⁺ + Y⁺ + A⁺

I⁺ + P + O⁺ + Z⁺ + Y⁺ + A⁺ / I^- + P+ O⁺ + Z⁺ + Y⁺ + A⁺

Question 9 of 10

Question 10 of 10

10. Capping of RNA is necessary as_______

To prevent the transcript from sticking to DNA

It has a rolling action and condenses the transcript as it is produced

It helps us distinguish 5’ from 3’ end

To protect the transcript from exonuclease

Question 10 of 10