Question

Which of the following will not effect the assembly of the eukaryotic transcription initiation complex but is expected to prevent the initiation of transcription?

a. mutation of the TATA box.
b. Absence of TFIID.
c. Absence of TFIIB.
d. Absence of ATP.
e. Absence of RNA polymerase II.

Answer 1

The absence of ATP will not affect the assembly of the eukaryotic transcription initiation complex, but it will prevent the initiation of transcription because ATP is necessary for the phosphorylation of RNA polymerase II and the unwinding of DNA.

Step-by-step explanation:

The option that will not affect the assembly of the eukaryotic transcription initiation complex but is expected to prevent the initiation of transcription is d. Absence of ATP. The transcription initiation complex, composed of various transcription factors and RNA polymerase II, assembles at the gene promoter to begin transcription. However, ATP is required for the phosphorylation of RNA polymerase II and the unwinding of the DNA helix, both crucial steps for the initiation of transcription. Therefore, without ATP, the transcription initiation complex may be correctly assembled, but transcription will not actually start because the necessary enzymatic activities cannot take place.

Mutations in the TATA box, absence of TFIID, TFIIB, or RNA polymerase II would each affect the assembly of the transcription initiation complex and hence would not correspond to the situation described in the question.