Question

If a tRNA molecule has an anticodon which reads CAG, what was the codon on the mRNA molecule?
1) AUG
2) GTC
3) UAG
4) GUC

Answer 1

The code on the mRNA molecule would have been GUC.

Answer 2

The answer is 4)GUC
Remember that the base pairs for RNA are:
 Adenine-Uracel and Cytosine-Guanine

The base sequence for tRNA will be the complement of the mRNA sequence:
tRNA                  mRNA
C                           G
A                           U
G                           C