Question

a part of an mrna has the sequence ccg. which change to this sequence would indicate a missense mutation?
messenger
rna codons
a. cca
b. ccu
c. cgg
d. ccc

Explanation:

Step1: Understand missense mutation

A missense mutation is a point mutation in which a single nucleotide change results in a codon that codes for a different amino acid.

Step2: Analyze original codon

The original codon is CCG. Looking at the codon table, CCG codes for Proline (Pro).

Step3: Analyze each option

• Option A (CCA): CCA also codes for Proline. So, no amino - acid change.
• Option B (CCU): CCU also codes for Proline. So, no amino - acid change.
• Option C (CGG): CGG codes for Arginine (Arg). There is an amino - acid change from Proline to Arginine.
• Option D (CCC): CCC also codes for Proline. So, no amino - acid change.

Since only in option C (CGG) there is a change in the amino - acid coded by the codon compared to the original codon (CCG), it indicates a missense mutation.

Answer:

C. CGG