Question

A small portion of the human transport protein amino acid sequence is shown below. The upper sequence is associated with darker skin, and the lower sequence is associated with lighter skin. What DNA base-pair change created the light-skin form of the human protein from the gene that coded for the dark-skir form? Ala-Gly Ala ThrPhe Ala Gly-Thr-Thr - Phe SECOND BASE SUAU TI Phe TUUU UUC UUA UUG] TUCU UCC UCA UCG Ser (UAC LUGU) UGC UAA Stop UAG Stop UGG TIP Jei TCCU TI CUU) CUC CUA CCC | Pro Leu CAU CAC] CAA CAG CGU) CGC CGA CGG Arg - CCA CUG (CCG I - You - mi AUU] AUC Ile LAUA AUG Met TACUL TAAU ACC Thr AAC ACA AAA AAG AGU] AGC AGA AGG Arg or Start (ACG GUU1 GUC GUA Val [GCU) GCC GCA (GCG) Ala TGAU) GAC GAA] GAG SGGU GGC GGA GGG (GUG

Answer 1

Because there is change from ala to thr in the human protein,the sequence of the non-template strand must have been altered from a G in the first position to a A in the first position. The base pair change must have been a GC base pair to AC base pair in the DNA coding for first position of the codon.

This is the cases of mis-sense mutation in which single amino acid change is found.