To determine the complementary coding triplet in mRNA for a given DNA triplet, we need to understand the basic rules of base pairing between DNA and mRNA. DNA is typically double-stranded, but during transcription, the DNA strand is used as a template to produce a single-stranded mRNA molecule.
Here’s the step-by-step process:
1. Identify the DNA triplet:
The given DNA triplet is TAC.
2. Understand the base pairing rules:
DNA and mRNA pair up according to specific rules:
- Adenine (A) in DNA pairs with Uracil (U) in mRNA.
- Thymine (T) in DNA pairs with Adenine (A) in mRNA.
- Cytosine (C) in DNA pairs with Guanine (G) in mRNA.
- Guanine (G) in DNA pairs with Cytosine (C) in mRNA.
3. Apply the base pairing rules to the DNA triplet TAC:
- The first nucleotide in the DNA triplet is T, which pairs with A in mRNA.
- The second nucleotide in the DNA triplet is A, which pairs with U in mRNA.
- The third nucleotide in the DNA triplet is C, which pairs with G in mRNA.
By following these rules, the complementary mRNA triplet for the DNA triplet TAC is:
- T (in DNA) -> A (in mRNA)
- A (in DNA) -> U (in mRNA)
- C (in DNA) -> G (in mRNA)
Therefore, the complementary coding triplet in mRNA is AUG.
Thus, the correct answer is:
O c. AUG
