BSC 315 Lecture Notes - Lecture 18: Sickle-Cell Disease, Missense Mutation, Frameshift Mutation
5 Mar 2017
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Some chemicals or radiation damage bases or integrity of. Large-scale changes in dna/chromosome structure: aneuploidy (too many / too few chromosomes, chromosomal rearrangements: translocations, inversions. Small changes: 1 or a few base pairs = point mutations. Point mutations: substitutions: one base replaces another. Transition: purine changes to purine, and pyrimidine to pyrimidine (a . Transversion: purine to pyrimidine, and pyrimidine to purine (c g, t . Insertion and deletion: one of a few bases are inserted or deleted: mutations > proteins. Insertion / deletion: frameshift mutation: translation reading frame problem. Result: inappropriate readi(cid:374)g fra(cid:373)e (cid:862)do(cid:449)(cid:374)strea(cid:373)(cid:863) fro(cid:373) deletio(cid:374); multiple missense substitutions. All frameshifts eventually introduce a nonsense codon, often after one or more missense codons. Mutations in non-coding regions may affect expression. Predict the effect of a change in the dna sequence of the promoter so that it is no longer recognized by rna polymerase.
