Question

Which type of mutation always creates a stop codon?

Answer 1

Hello

Q: Which type of mutation always creates a stop codon?

A: Nonsense mutation always creates a stop codon.

Answer 2

Answer: The correct answer is Nonsense mutation.

Nonsense mutation is a type of point mutation which results due to change in one nucleotide sequence in the DNA. Due to this, it forms stop codon in the mRNA which is transcribed from the DNA. This results in the premature termination of protein synthesis as truncated proteins are formed due to stop codon.

For example- DNA: 5' - ATG ACT CAC TGA CGG ACT AGC  TGA - 3'

                                3' - TAC TGA GTG  ACT GCC TGA TCG  ACT - 5'

                   mRNA: 5' - AUG ACU CAC UGA CGG ACU AGC UGA - 3'

In this example, due to mutation at single nucleotide ( in DNA ), stop codon UGA is synthesized in the mRNA. Thus, it is a nonsense mutation.