This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: MUTATIONS Genetic experimentation is fundamentally a search for phenotypes and the genomic changes that created them. Morphological mutations are changes in the appearance of an organism. Wing mutants ( m, vg, dp ) are a classic example of this kind of mutation in Drosophila . Synthetic mutations affect an organism's ability to produce a biological product. Eye color mutants (e.g. w,bw,se ) fall into this category. Other types of mutations are more difficult to approach experimentally. For example, regulatory mutations , often show pleiotropic phenotypes in which there is a mixture of overlapping traits. This is due to a defect in a gene that is responsible for turning a number of genes on and or off like sisB and runt in Drosophila or PKU (phenylketonuria) in humans. Another important classification of mutant is the conditional mutation . Conditional mutations are manifested under a particular set of growth parameters, but not all. Temperature-sensitive , ts, mutations become evident at one temperature but not another. This characteristic of conditional mutation has made them especially sought after for the study of essential genes. By definition the loss of an essential gene would be lethal to an organism; ergo, they are the most difficult genes to study. By isolating a conditional form of the mutation (i.e. a conditional lethal ) it is possible to study the phenotype to determine the biochemical and or physiological function of the gene. A fine example of this kind of mutations is the cell cycle mutation like cdc2 in which growth stops at the non-permissive temperature. What is a mutation: A mutation occurs when an inheritable change has been introduced into the genomic sequence. There are basically two kinds of mutations: A change in the nucleotide sequence due to the substitution of one base pair for another....
View Full Document