G 2 the lac superrepressor mutation usually dominant

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: s-of-function and Gain-of-function mutations • Gain-of-function mutations • e.g. 2: The lac superrepressor mutation • Usually dominant, as the protein is now doing something it did not previously do. and causes effect Other types of mutations stops wild type protein fro funtcioning • Dominant negative: mutant protein interferes with the function of the wild type protein, leading to a dominant loss-of-function phenotype • Regulatory: disrupts the regulation of a gene’s expression (promoter or enhancers) – May be lof or gof mutations, dominant or recessive Other types of mutations • Conditional mutations: lof mutations in which the protein is functional under some conditions, but nonfunctional in others – Temperature sensitive mutations • Lethal mutations cause death, of either the cell or the organism. • Almost always recessive. Why? if mutation is lethal, progeny cannot be proopagated Suppressor mutations Suppressor mutations • Two classes of suppressor mutations: • Intragenic suppressor mutations are in the same gene as the original mutation. • May change a second nucleotide in the codon altered by the original mutation, so that it specifies the WT amino acid. • May suppress a frameshift mutation: • By inserting a nucleotide(s) after a deletion • Or deleting a nucleotide(s) after an insertion. all codon downstream become normal if 1 is added triplet code is degenerate Text Suppressor mutations Intragenic suppressor mutations • May make a compensatory change in a protein • A first missense mutation may alter the folding of a protein by destroying an interaction between amino acids. make change elsew...
View Full Document

Ask a homework question - tutors are online