Genetic Code and Silent Mutations

00:00 1 marks

The table shows the mRNA codons for three amino acids.

Valine	Threonine	Proline
GUU	ACU	CCU
GCC	ACC	CCC
GCA	ACA	CGA
GCG	ACG	CCG

Which substitution mutation of a base triplet on a DNA strand will lead to the same polypeptide being formed at translation?

A

TGA to TCA
B

CGT to CTA
C

CAA to CGA
D

GCT to GGA

Hint Hint

Hint

Remember that the DNA strand provided is likely the template (non-coding) strand. Transcribe the DNA triplets into mRNA codons using base pairing rules (A pairs with U, T pairs with A, C pairs with G, G pairs with C) and then use the table to see which mutation results in the same amino acid.

Answer Answer
Mark Scheme Mark Scheme
Explanation Explanation
Examiner Tips Examiner Tips
Common Errors Common Errors
Real World Context Real World Context

Answer Answer

Complete Answer

GCT to GGA

Mark Scheme Mark Scheme

Answer Explanation Answer Explanation

Examiner Tips Examiner Tips

Common Errors Common Errors