Question

The triplet UUU codes for-
A. Leucine
B. Methionine
C. Phenylalanine
D. Glycine

Answer 1

Hint: A codon is a trinucleotide sequence that is formed from the combination of a sequence of 3 nucleotides that forms a unit of the genetic code. It is a sequence of nucleotides in DNA and RNA that codes for a specific amino acid.

Complete answer:
A codon, nucleotide triplet in DNA and RNA codes for a specific amino acid. There are a total of 20 basic amino acids and to code them 64 codons are present. These codons are formed from the nucleotide bases- A(Adenine), T(Thymine), C(Cytosine), and G(Guanine) in DNA and A(Adenine), U(Uracil), G(Guanine), and C(Cytosine) in RNA. Their main function is to code for amino acids during the process of transcription. There are two types of codons- Sense codons (that code for an amino acid) and Signal codon. Signal codons consist of start codons and stop codons. Start codon codes for Methionine which is an amino acid that starts the process of translation and stop codon codes for amino acids that stop the process of translation.

Let us analyze the options to find the correct answer.

Option A: Leucine amino acid is coded by the codons UAA, UUG, CUU, CUC CUA, and CUG. Therefore, this is the incorrect option.
Option B: Methionine amino acid is coded by the codon AUG. Therefore, this is the incorrect option.
Option C: Phenylalanine is coded by the codon UUU and UUC. Therefore, this is the correct option.
Option D: Glycine is coded by the codon GGU, GGC, GGA, and GGG. Therefore, this is the incorrect option.

Hence, the correct answer is option (C)

Note: The triplet codon is continuous, non-overlapping, degenerate, universal, unambiguous and degenerate. The degeneracy or redundancy of codon means that more than one codon codes for an amino acid. This property appears due to the presence of 64 triplets for 20 basic amino acids.