Why are frameshift mutations more likely than missense mutations to result in proteins that lack normal function?
Frameshift mutations arise from the addition or deletion of one or more bases that are not a multiple of three. When translated, this addition or deletion will alter the reading frame and therefore the amino acid sequence from the site of the mutation to the end of the protein product. In addition, frameshift mutations often result in premature stop codons in the new reading frame, leading to shortened protein products. A missense mutation changes only a single amino acid in the protein product. 9. Describe the Streisinger model for frameshift formation. Show how this model can explain mutational hot spots in the lacI gene of E. coli. 10. Diagram two different mechanisms for deletion formation. How do DNA sequencing experiments suggest these possibilities? 11. Describe two spontaneous lesions that can lead to mutations. Depurination results in the loss of adenine or guanine from the DNA. Because the resulting apurinic site cannot specify a complementary base, replication is blocked. Un
