Consider the following statement A gainoffunction mutation a

Consider the following statement: \"A gain-of-function mutation and a nonsense mutation both describe changes to the coding region of a gene.\" Is this statement correct or incorrect? Support your answer with an explanation.

Solution

Yes, the statement is correct...both \'gain of function\' mutation and a \'nonsence mutation\' occurs in the coding region of the gene. However, they are entirely different in nature; as one leads to introduction of a new function to the gene due to a random change in the coding sequence whereas the other lead to premature termination of transcription of mRNA resulting in a non-functional protein.

Gain of function mutation is the type of mutation in which the altered gene product possesses a new molecular function or a changed pattern of gene expression and confers new or enhanced activity on a protein. However, gain of a function not necessarily means improved function! These type of mutations are almost always Dominant or Semidominant, wherein the effect of mutation is visible/ detectable at phenotypic level. It is basically a random, change purely by chance, conferring to some new function to the gene

On the other hand, a nonsense mutation is a point mutation in a sequence of DNA that results in a premature stop codon. The mRNA formed in this case is truncated, incomplete and usually a nonfunctional protein product. As a result of this mutation, a stop codon (either of the three UGA, UAG or UAA) is introduced in the mRNA chain prematurely while transcription. This type of mutation occurs in the coding region of the gene.