1. TFIIB can bind to a promoter element in the core promoter of eukaryotes. This element is __________
a) Inr
b) BRE
c) DPE
d) TATA
Explanation: BRE stands for TFIIB recognition site. It is here that the element can bind. On the other hand TFIID binds at the TATA box.
2. Which of these is not a promoter element?
a) TATA box
b) DPE
c) CCAAT box
d) Inr
Explanation: The CCAAT box is a part of the upstream activating elements which is upstream to the promoter. It is recognized by CTF or CCAAT recognizing Transcription Factor. The remaining options are part of a core promoter.
3. Which would be an appropriate method to detect the core promoter regions in a eukaryotic gene?
a) Footprint
b) Sequencing
c) Linker scanning
d) S1 endonuclease
Explanation: In linker scanning method a small segment of the DNA is removed from promoter region and replaced with a random segment to see its effect on the transcription rate. Thus, as absence of promoter would lead to less transcription this method can be used to detect promoter elements.
4. Repressors are active only when they are at the proximity of the RNA polymerase as they directly associate with the pre-initiation complex. State whether this is true or false.
a) true
b) false
Explanation: Although often repressors directly associate with RNA polymerases it can also act by the means of a mediator as enhancers do. So, they could be close or far from the transcription start site.
5. Which of these class III promoter type resemble class II?
a) Type I
b) Type II
c) Type III
d) Type IV
Explanation: The Type III of class III promoter is a non-classical class III promoter which resembles type II. It has a TATA box, PSE and an upstream DSE. There is no 4th type of class III promoter and type I and II don’t resemble class II.
6. If you make a chimeric factor with the DNA binding element of an activator and a functional domain of a repressor, how will this factor behave?
a) It will act like a repressor
b) It will act like an activator
c) It will not be able to bind the DNA so although it binds via the repressing domain it won’t cause repression
d) Repression domain will be non-functional
Explanation: As activators and repressors have a domain organization it is seen that if a DNA binding domain is provided it doesn’t affect the activity. As long as the factor binds to the correct cis element it will still be a functional repressor
7. Which of this element is not orientation independent?
a) Enhancer
b) Silencer
c) Upstream activating element
d) Promoter proximal elements
Explanation: While upstream activating element is orientation independent, enhancers and silencers are position as well as orientation independent. On the other hand promoter proximal elements are orientation dependent.
8. Which of these promoter elements has a high propensity of developing mutation given the eukaryotic gene was inserted in prokaryotes?
a) CCAAT box
b) CPG islands
c) TATA box
d) Enhancer
Explanation: This is because prokaryotic methylases would methylate the C bases of the CPG region. Then it there is a de-amination of C base, it will resemble a T base which is not as easily distinguishable as U by UDG. So, this region is very mutagenic.
9. In which of the following chromosome compaction is absent?
a) Cellulomonas flavigena
b) Allium sativum
c) Panthera tigris
d) Saccharomyces cerevisiae
Explanation: Cellulomonas flavigena is a prokaryote, and unlike the rest which are eukaryotes they don’t have chromosome compaction and histones.
10. Histones are __________
a) Neutral
b) Positively charged
c) Negatively charged
d) Neutral with positive and negative domains
Explanation: HIstones are rich in positively charged amino acids namely lysine and arginine. Thus they have a net positive charge. This helps them to bind to the negatively charged DNA.