Question

The strand of dna used in the previous problem undergoes a mutation, such that the second c from the 3' end is changed to a
a. the mutant dna is shown below. what would change in the polypeptide? mutant dna: ...3' g c t a a g t c t 5'...

Answer 1

This mutation type is a substitution mutation. Substitution mutations may be silent or may have adverse effects (missense mutation).
Adverse effects come about because the change in codons in mRNA transcribed from the DNA strand. A point substitution can change the amino acid being coded for in the particular polypeptide change. If that animo acid is a structural residue of the protein, the structure of the protein will be altered, which may or may not lead to a change in protein function. If that particular amino acid is a catalytic residue of the protein, it may alter the 3D conformation and charge of the active site (if protein is an enzyme) or the binding site of protein. Function of protein formed from mutated DNA will be lost or altered.

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