Question

Now consider a single base mutation in a codon for leucine that creates a codon for phenylalanine. A true reversion changes the phenylalanine codon back to a codon for leucine. Which of the following leucine codon(s) could be mutated once to form a phenylalanine codon, and then mutated at a second site to restore a leucine codon?a. CUU
b. CUC
c. CUA
d. UUG
e. UUA
f. CUG

Answer 1

Answer:

options A, B, D and E

Explanation:

leucine codons include: UUA, UUG, CUU, CUC, CUA, CUG

phenylalanine codons include: UUU, UUC.

CUU          

replace C with U to give

UUU phenylalanine codon

replace underlined with A

UUA leucine codon

CUC

replace underlined with U

UUC phenylalanine codon

replace underlined with A or G

UUA, UUG  leucine codons

UUG

replace underlined with U

UUU phenylalanine codons

replace underlined with C

CUU leucine codon

UUA

replace underlined with U or C

UUU or UUC phenylalanine codons

replace U with C

CUU or CUC leucine codons