Question

Which one of the following is the main reason that a typical eucaryotic gene is able to respond to a far greater variety of regulatory signals than a typical procaryotic gene or operon?

(a) Eucaryotes have three types of RNA polymerase.
(b) Eucaryotic RNA polymerases require general transcription factors.
(c) The transcription of a eucaryotic gene can be influenced by proteins that bind far from the promoter.
(d) Procaryotic genes are packaged into nucleosomes.
(e) none of the above

Answer 1

The main reason why a typical eukaryotic gene has a greater variety of regulatory responses compared to a prokaryotic gene or operon is that eukaryotic genes can be regulated by proteins that bind sites distant from the promoter.

Step-by-step explanation:

The main reason that a typical eukaryotic gene can respond to a far greater variety of regulatory signals than a typical prokaryotic gene or operon is that the transcription of a eukaryotic gene can be influenced by proteins that bind far from the promoter, as stated in option (c).

Unlike prokaryotic cells, eukaryotic transcription involves several transcription factors that can bind to complex promoters and regulatory sequences, some of which can be located a thousand or more base pairs away from the gene they regulate. This allows for a higher level of regulation as a result of the increased complexity in the interactions between these regulatory proteins and the core transcription machinery.

Eukaryotes have three types of RNA polymerase, and the fact that eukaryotic RNA polymerases require general transcription factors is also an important aspect of their transcriptional regulation. However, the ability of regulatory proteins to bind at distant sites and still influence transcription suggests a higher level of potential regulation in eukaryotic genes compared to their prokaryotic counterparts, which do not have this same complexity of gene regulation.