Answer:
A mutation, which may arise during replication and/or recombination, is a permanent change in the nucleotide sequence of DNA. Damaged DNA can be mutated either by substitution, deletion or insertion of base pairs. Mutations, for the most part, are harmless except when they lead to cell death or tumor formation. Because of the lethal potential of DNA mutations cells have evolved mechanisms for repairing damaged DNA.
Types of Mutations
There are three types of DNA Mutations: base substitutions, deletions and insertions.
1. Base Substitutions
Single base substitutions are called point mutations, recall the point mutation Glu -----> Val which causes sickle-cell disease. Point mutations are the most common type of mutation and there are two types.
Transition: this occurs when a purine is substituted with another purine or when a pyrimidine is substituted with another pyrimidine.
Transversion: when a purine is substituted for a pyrimidine or a pyrimidine replaces a purine.
Explanation:
