​A portion of an mRNA encoding a protein is shown below, with the start codon underlined.

5’ …..CCUCAAACAGACACCAUGUUGCACCUGACUCCU….3’

Which one of the following tRNAs is most likely used for translating the second codon in the open reading frame of the protein?

​

Correct option is A

​Explanation:

Step 1: Identify the Open Reading Frame (ORF)

-The start codon (AUG) is the first codon that signals the beginning of translation.
-The next (second) codon in the reading frame follows immediately after AUG.
-The second codon is UUG, which codes for the amino acid Leucine (Leu).

Step 2: Determine the Complementary Anticodon

-Codon-anticodon pairing follows complementary base pairing rules (A-U, G-C).
-The anticodon must be complementary and antiparallel to the codon.
-The codon UUG (5' to 3') requires an anticodon CAG (3' to 5').

Information Booster:

1. Codon-Anticodon Base Pairing:
2. Codons are read 5' to 3' direction.
3. Anticodons in tRNA are complementary and antiparallel (3' to 5').
4. Start Codon (AUG) initiates translation and recruits Methionine (Met).
5. Leucine (Leu) is encoded by multiple codons:
6. UUA, UUG, CUU, CUC, CUA, CUG
7. tRNA Selection and Wobble Base Pairing:
8. The third base in the codon can sometimes allow alternative base pairing, leading to degeneracy in the genetic code.