Question

please answer all parts

25) A few points: Explain how a single nucleotide substitution in the sequence of a gene can: A) cause a mutation (a single amino acid replacement) in the protein coded by the gene and B) how such a single nucleotide substitution does not necessarily lead to a mutation in the protein (a silent mutation). Be very specific and use real examples for the nucletotides and the resulting amino acid in the protein. You must provide the “normal” nucleotides and the “mutated” one(s) as well as the “normal” protein and the “mutant”. Case A: “normal” (original) sequence: sequence with substitution:_ "normal" gene product: product: ; mutant gene Case B: “normal” sequence: with substitution: ; sequence "normal" gene product: product: ; mutant gene

Answer 1

(A) In case of silent mutations, the amino aud sequence op the chain does not change due to single nucleotide base mutation and henc the mutated the gene expreesses same amino acid the normal one, 11 Case A ; normal" AUG AUC GAA UCG GAU. Coriginal) sequence : with subs tite tion: sequence AUG AUC GACOCG GAU. AUG AUC GAA norem a!" UCG GAO. gene product : Met gle Glo Sere Ala Mutant AUG AUC preoduct : AUC GAC UCG gene Met Sle Glo ser Ala. Herce GAA and both GAC codes for Glutamic Acid,

(B) On case is amino aod change does not affect the due + function conservative mutations, there to the point mutation but activity of the gene. conservative mutation, different property than ore case non the wild amino acia type change results in fase to con sereva tive replacement : "normal" sequences AUG AUC ACC UCG GAU, sequence with substitution : AUG AUC AGG UCG GAU , lli normal" Met preoduct : sle The Ser gene Ala. Mutant Sere Arg. Ala. gene product : Met sle Non- conservative replacement : ܕ ܘ AUC TGC UCG GAUS. " noremal" sequence AUG sequence with substitution : AUG AUC ACG UCG GAU. "normal" Met preoduct : gene gle cys UGG GAU. Mutant Met product : ge. Thre gene UCG GAU.