Question

Gene A is thought to be associated with color blindness. The protein corresponding to gene A is isolated. Analysis of the protein recovered shows there are actually two different proteins that differ in molecular weight that correspond to gene A. What is one reason why there may be two proteins corresponding to the gene?

a) Alternative splicing of mRNA
b) Transcriptional repression
c) DNA methylation
d) Enhancer activation

Answer 1

The presence of two different proteins for gene A is most likely due to alternative splicing of mRNA, which allows one gene to produce multiple protein variants.

Step-by-step explanation:

The question deals with the molecular basis of protein diversity arising from a single gene. In the context of gene A being associated with color blindness and two proteins differing in molecular weight, the most plausible explanation is alternative splicing of mRNA. Alternative splicing is a post-transcriptional process that allows for the production of multiple protein variants from a single gene by selectively including or excluding certain segments of the RNA transcript.

Post-transcriptional control mechanisms such as alternative splicing, RNA splicing, proteolytic cleavage, and phosphorylation can explain the existence of different protein forms despite having the same original gene sequence. Among the given options, transcriptional repression, DNA methylation, and enhancer activation do not directly lead to the production of multiple proteins from a single gene.