Question

Regulation of gene expression occurs primarily at the level of transcription. What would be different if cells controlled gene expression primarily at the level of translation?

	a.	The ability to rapidly respond to environmental change would be reduced.
	b.	Genes would no longer be transcribed efficiently.
	c.	Cells would expend significantly more energy.
	d.	Many different protein isoforms would be produced.
	e.	Translation of mRNA would not occur.

If an enhancer associated with a gene was deleted or mutated, what would be the effect on levels of gene expression?

	a.	Gene expression would be reduced or not occur at the appropriate time.
	b.	The gene would not be recognized by RNA polymerase.
	c.	Gene expression would not occur at all.
	d.	Gene expression would increase or occur at the inappropriate time.

Cells regulate gene expression at the level of translation by:

	a.	controlling ribosome binding at the 5' end of mRNA.
	b.	controlling the length of the polyA tail.
	c.	controlling the amount of amino acids used.
	d.	a and b
	e.	a, b and c
	f.	a and c

Answer 1

1. The correct answer is option e i.e. Translation of mRNA would not occur. The regulation of gene expression conserves energy and space. It would require a significant amount of energy for an organism to express every gene at all times. The lesser the energy needed, better is the control of gene expression. As during translation, the control or regulation of gene expression mostly occurs at translation initiation and thus prevents any further translation of mRNA. Along with this, some antisense RNA can bind to mRNA and further controls the initiation of translation.

2. The correct answer is option a i.e. Gene expression would be reduced or not occur at the appropriate time. Enhancers are DNA regulatory elements that activates transcription of a gene or genes to higher levels than would be the case in their absence. Therefore, mutation or deletion of enhancers associated with a gene would result in reduced level of that gene expression.

3. The correct answer is option e i.e. a, b and c (controlling ribosome binding at 5' end of mRNA, controlling the length of poly-A tail, and controlling the amount of amino acid used). The regulation of gene expression at transcription level is mostly associated with inhibition of translation initiation. Thus, any element which is important during translation initiation is either inhibited or prevented.