To determine which DNA codons code for aspartic acid, we first need to know the mRNA codons that correspond to aspartic acid. Aspartic acid is coded by the mRNA codons "GAU" and "GAC".
Next, let's find the DNA codons that correspond to these mRNA codons, as DNA is transcribed into mRNA. For mRNA codons, we can find the corresponding DNA codons by replacing uracil (U) with thymine (T) and replacing the bases with their complementary pairs (A with T, C with G, G with C, and U with A):
- GAU (mRNA) translates to CTA (DNA).
- GAC (mRNA) translates to CTG (DNA).
Now let’s compare the options you provided with our findings:
- CAG - This codes for Glutamine (not aspartic acid).
- CTA - This is the DNA codon for GAU, which corresponds to aspartic acid.
- CTG - This is the DNA codon for GAC, which corresponds to aspartic acid.
- GAC - This is the mRNA codon, not DNA.
- GAU - This is also the mRNA codon, not DNA.
Based on this information, the correct DNA codons that code for aspartic acid are:
- CTA
- CTG
So, the answer is CTA and CTG.