Biology 2581B Chapter Notes - Chapter 5: Ectopic Expression, Haploinsufficiency, Frameshift Mutation

• School: Western University
• Department: Biology
• Course: Biology 2581B
• Professor: David R Smith

Document Summary

Textbook lecture 8 allele classifications (459) Mutations in a gene"s coding sequence may alter the gene product. Nonsense mutations: the shorter truncated proteins lack all amino acids between the amino acids encoded by the mutant codon and the c terminus of the normal polypeptide. Mutations outside the coding sequence can alter gene expression. Promoters and termination signals in the dna instruct rna polymerase where to start and stop transcription. If hard to recognize the start site = no transcription. Mutation in splice sight: absence of mature mrna and thus no polypeptide. Mutations affect ribosome binding site: lower affinicty for small ribosomal subunit = diminish efficiency of translation. Most mutations that affect gene expression reduce gene function. Loss of function mutation: any mutation inside or outside a coding region that reduces or abolishes protein activity. Null/amorphic: completely block the function: prvent synthesis of the protein or promote synthesis of a protein incapable of carrying out its function.