Mutations

What is a mutation?

•Mutation- change in the nucleotide sequence of DNA

Why do mutations matter?

➔ Changing nitrogen bases can change the protein that is

being built.
◆ Remember the DNA code is instructions for creating

proteins and running the organism.

➔ 3 nitrogen bases code for an amino acid, amino acids are

monomers of proteins.

➔ Ex. CTA
(Cytosine-Thymine-Adenine)

Types of Mutations

1. Point mutation: AKA Substitution Mutation

•A chemical change in just one base pair

• Example: Substituting a Cytosine (C) for an Adenine (A).

• Can cause the wrong amino acids to be made
• Can cause the early termination of a protein chain if it is a stop

codon (UAA, UGA, UAG)

Types of Mutations

2. Frameshift mutation:

•Mutations that change the “frame” of the amino acids
•Involves a gain or loss of a nucleotide which can cause
a change in the codon!
•WORST KIND!
•Examples: insertion and deletions

Frameshift Mutations

•Deletion: nucleotide gets
lost during replication or
transcription

•Insertion: extra
nucleotide is attached
to the sequence