Question

why are temperature sensitive mutations more likely to involve missense over nonsense mutations? Please write clearly!

Answer 1

In temperature sensitive mutation, protein is active at one temperature but inactive at higher temperatures. It is usually a result of missense mutation in which interactions between particular amino acids are weakened, thus broken as temperature is raised. These mutations are valuable in studying lethal mutations as the organism can grow at the permissive temperature. A nonsense mutation is a genetic mutation in a DNA sequence that results in a shorter, unfinished protein product.

The study of temperature sensitive mutant phenotype is fundamental to gene identification and for dissecting essential gene function. Temperature sensitive mutations are typically missense mutations, which retain the function of a specific essential gene at standard low temperature (permissive), lack that function at a defined high ( non-permissive) temperature and exhibit partial ( hypomorphic) function at an intermediate (semi-permissive) temperature. Such mutants make possible the analysis of physiologic changes that follow controlled inactivation of a gene or gene product by shifting cells to a non- permissive temperature, offering a powerful approach to analysis of gene function.