Use the table of the standard genetic code to provide short answers to the follo

Question

Use the table of the standard genetic code to provide short answers to the following questions. What amino acid is encoded by CGA? In one eukaryote gene, a mutation changes the C-G base pair that coded for a 5' C in a CGA codon to a T-A base pair. What codon is present in the mutant mRNA? Give the name for this type of mutation, and describe its effect on translation? Most mRNAs are translated more than once. Will the mutant mRNA also be translated more than once? It not, describe the mechanism that prevents its undergoing multiple rounds of translation. Explain how a mutation in a second gene could suppress the effects of the C-G to T-A mutation, Indica what type of gene could have such a mutation, how this gene would have to be mutated m order to suppress the first mutation, and what affect this would have on the first gene's protein product.

Explanation / Answer

a. CGA is encoding Arginine.

b. Given that there is mutation where C-G changes to T-A

then the resultant Amino acid codon will be TAA but there is U in mRNA so the codon will be UAA

UAA is a stop codon so there will be termination of the protein synthesis.

and a mutation that will cause the conversion of the normal amino acids to the stop codon and premature termination of the translation and truncated non functional protein is called nonsense mutation.

c. nonsense mediated decay is the mechanism lying behind the prevention of mRNA to undergo multiple rounds of translation.

nonsense-mediated mRNA decay pathway, degrades mRNAs containing nonsense mutations before they are translated into nonfunctional polypeptides.

d.Extragenic suppression will revert back the mutation of C-G to T-A into T-A to C-G.

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