Question

Which codon does not have tRNA?
A. Start codon
B. Stop codon
C. AUG
D. GGG
E. UUU

Answer 1

Hint: One can define the term codon as a trinucleotide sequence of DNA or RNA. It generally resembles a precise amino acid. We can say that the codon is the name given by us to a stretch of the three nucleotides. It is said that there are 64 codons possible in total. However, each of them is normally composed of three of the four possible nucleotides. On the other hand, only about 20 amino acids are found in maximum biotic systems.

Complete answer:
> Option B:
The UAA, UAG, UGA are said to be the stop codons. It is known that they are incapable of coding for any amino acid. We can say that this is the reason that they have the absence of tRNA molecules in them.

> Option A:
We can say that the Start codon is a type of AUG. The AUG also codes for methionine. The tRNA is there in the molecules which help in carrying methionine in eukaryotes and formylated methionine in prokaryotes.

> Option C:
The methionine is coded by the AUG. thus, we can say that there is a presence of tRNA molecule in them and they help in carrying the methionine

> Option D:
The glycine is coded by GGG. Thus, we can say that there is a presence of a tRNA molecule in them and they help in carrying the glycine.

> Option E:
The phenylalanine is coded by the UUU. Thus, we can say that there is a presence of tRNA molecules in them and they help in carrying the phenylalanine.

Hence, the correct answer is option (B).

Note:
The relationship between the sequence of DNA bases (such as A, C, G, and T) in a gene and the corresponding protein sequence that it encodes is generally described by the genetic code. The sequence of the gene in groups of three bases can be read by the cell. As we know there are 64 codons in total. However, 61 out of them are amino acids the remaining three are used as stop signals.