Question

Under which condition will the yeast express a-alpha mating type?

(a) HAT activation

(b) TBP activation

(c) HDAC inactivation

(d) HAT inactivation

I had been asked this question by my school principal while I was bunking the class.

Origin of the question is Transcription in Eukaryotes : Gene Silencing at Telomere in division Gene Expression : Transcription Prokaryotes of Cytogenetics

Answer 1

Correct answer is (d) HAT inactivation

Easy explanation: HAT acetylates the histone H3 and H4 so it activates the gene while HDAC deacetylates them and inactivates the genes. Under condition when HAT is active but HDAC is inactive we will get an expression of both the telomere gene which is normally repressed. This will lead to a-alpha mating type.