IMAT 2012 Q47 [Gene Expression]

Gene expression can be regulated by:

A. transcription factors
B. DNA replication factors
C. RNA polymerase
D. rough endoplasmic reticulum
E. the position of the genes on the alleles

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The answer to this question is A.

Why is choice A the correct answer?

  • The question is asking you to discern which among the choices is involved in the regulation of gene expression.
  • As we know, transcription is the process of copying a DNA sequence into RNA, which will be later translated into proteins. Gene expression on the other hand is when a gene within a DNA sequence is used for the production of specific proteins in accordance with the specific gene that is induced to be expressed.
  • Now the question is, where does regulation come into place? Here’s where transcription factors are important. These transcription factors binds to the DNA at a specific sequence, and whether they are activators or repressors, they dictate how accessible the DNA is for the RNA polymerase to bind. This regulation is important since RNA polymerases are responsible for the process of transcription.
  • Thus in summary, choice A is the correct answer since transcription factors control the expression of specific genes.

Why are the other choices incorrect?

  • All the other choices have 2 things in common: First, they are all just merely involved the process of replication, transcription, and translation. Meaning that they are all just parts of the process involved with the central dogma of molecular biology, but, which leads to the second fact that they have in common, is that none of them are involved in the regulation, as described earlier, nor serve any function similar to transcription factors in terms of gene expression. Thus, the combination of these 2 facts makes them the incorrect answers.