Second letter UCU UAC UAA Stop UGA Stop A UAG Stop UGG TpG UCA Leu UcGCGU CAC CU

Question

Second letter UCU UAC UAA Stop UGA Stop A UAG Stop UGG TpG UCA Leu UcGCGU CAC CUC Leu CCA Gin CGG CUG CCG AGU serc AAU Asn AGC AGA AGG GGU GCC Ala GAAGluGGG Arg G AUA AUG Met ACCG GUU GUC Val GCA GCU GGA GUGJ GCG AUG also serves as the start codon 4. The mutation that causes cystic fibrosis changes the structure of CFTR (cystic fibrosis transmembrane conductance regulator). CFTR is a membrane protein that transports chloride ions across cell membranes. The normal CFTR protein is 1480 amino acids long and has a molecular weight of 168,173 Da. How many of the nucleotides present in the mRNA strand (at the ribosomes) are required to code for these amino acids? a. Most mutations (70%) in patients with cystic fibrosis are due to a deletion of 3 nucleotides Amino acid number 508 is lost. This mutation is known as F508 (or delta F508). b.

Explanation / Answer

4.a. Each amino acid is coded by triplet base hence 1480 *3= 4440 bases.

i. In this basically third base of isoleucine and initial first two bases of phenylalanine is lost but due to third base of phenylalanine sequence of isoleucine is recovered.

ii. here actual lost of phenylalanine and F stand for Phenylalanine.

iii. 507 is Isoleucine that is coded by ATT

iv. because in this amino acid that is lost is 508 but 507th amino acid again coded by the triplet base and that amino acid is unchanged.

iV . yest it is a frame shift mutation because third base of isoleucine was removed and initial two bases of phenylalanine were remove that create the change in frame but due to third base that joined with two bases of isoleucine hence it again encode for isoleucine amino acid.

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