Question

Smallest part of dna which undergoes mutation is called

Answer 1

$\textbf{Muton}$ is the smallest part of DNA which undergoes mutation.

$\textbf{What is Mutation ?}$

You can say it as a chemical change in DNA molecule, which could lead to protein synthesis with a changed amino acid sequence.

$\textbf{What causes it ?}$

Main responsible cause of it are radiantions, Chemical agents and even viruses.