Question

If a triplet on template DNA is AAA, what will be the anticodon on tRNA
A. UUU
B. AAA
C. TTT
D. AUG

Answer 1

An anticodon is a three-nucleotide unit that corresponds to an mRNA codon's three bases. Each tRNA molecule has its own anticodon triplet sequence, which can generate three complementary base pairings with one or more amino acid codons. Due to wobble base pairing, anticodons can only pair with one codon. In many cases, the anticodon's initial nucleotide is inosine, which can hydrogen bond to more than one base in the corresponding codon position.

Complete answer:
Option A UUU : Here, on the template DNA, the given sequence is AAA. Hence it will be transcribed to mRNA having the sequence UUU. But the tRNA which will attach to this mRNA will have the anticodon sequence AAA.
Hence option A is not correct.
Option B AAA : AAA will be transcribed to mRNA as UUU if the template strand of DNA has AAA. The tRNA which would attach to this mRNA will have an anticodon sequence of AAA.
Since AAA is the sequence of anticodon on tRNA, option B is the correct answer.
Option C TTT : The template DNA has AAA, will get transcribed into UUU and not TTT, since it is mRNA. After that, the tRNA will have the anticodon sequence of AAA.
Hence option C is not correct.
Option D AUG : The anticodon on tRNA of template DNA having AAA will be AAA. AUG is a start codon. The start codon is the first codon of a ribosome-translated transfer RNA (tRNA) transcript.
Hence option D is not correct.

Option B is the correct answer.

Note:
The decoding site, also known as the ribosomal A-site, is where the codons and anticodons on the ribosome create a short, double-stranded RNA helix. It is located between the head and the body of the ribosomal small subunit in the neck region. There are also areas of the rRNA that are involved in a conformational alteration in the near neighborhood.