Insertion (DNA Mutation) — Definition & Examples

What's a DNA Mutation?

Mutations are changes in genetic material. They often happen because cells make mistakes when they copy their DNA. Remember that DNA codes for proteins, so any error in the DNA sequence can alter the protein being made.

What's an Insertion Mutation?

Insertion means exactly what you would expect—an extra nucleotide is added into a DNA sequence. Because DNA sequences are grouped into chunks of three, called codons, inserting an extra nucleotide can throw everything off.

Every codon following the mutation will not match the original DNA sequence.

Insertion Mutations and Frameshift Mutations

When the codons of a DNA sequence are messed up, it is called a frameshift mutation. This type of mutation is more significant than a point mutation because it influences the entire DNA sequence following the mutation.

Frameshift mutations mean that the entire DNA sequence has shifted. The earlier in the DNA sequence that a frameshift mutation occurs, the more messed up the protein will be.

Inserting base pairs can also cause a premature end to translation if a stop codon is accidentally made. This means the protein will be shorter than normal and could end up not functioning at all.

$$\color{#8925AE}{\text{Vocabulary Review:}}$$

$\color{#8925AE}{\text{Mutation}}$ : A change in genetic code

$\color{#8925AE}{\text{Point Mutation}}$ : A mutation that occurs at a single point in the DNA sequence

$\color{#8925AE}{\text{Frameshift Mutation}}$ : A mutation that causes all the nucleobases following it to be shifted

$\color{#8925AE}{\text{Codon}}$ : A group of three nucleobases that codes for a specific amino acid

$\color{#8925AE}{\text{Insertion}}$ : An extra nucleotide is inserted into a DNA sequence

$\color{#8925AE}{\text{Substitution}}$ : A nucleotide is substituted for another nucleotide in a DNA sequence

$\color{#8925AE}{\text{Deletion}}$ : A nucleotide is deleted from a DNA sequence

Summary of Insertion Mutations

Insertions can range from a single nucleotide to an entire section of a chromosome.

Insertion mutations are very bad because they can disrupt the reading frame. If even one nucleotide is deleted, it can cause all amino acids in the chain after that point to be different. This results in an entirely different protein than the desired one. Changing the reading frame is called a frameshift mutation.

$$\text{AUGAACGAACUGUCU}$$

If this is the original RNA sequence, the reading frame would look like this: $$\text{AUG/AAC/GAA/CUG/UCU/}$$ If the first nucleotide were to be deleted, it would shift the reading frame one place. $$\text{UGA/ACG/AAC/UGU/C}$$ This new sequence will produce an entirely new protein.

When three nucleotides are inserted, it is called an in-frame mutation because it does not disrupt the reading frame.

(Video) Mutations

by Amoeba Sisters

An insertion mutation is when an extra nucleotide base is added into the DNA code during DNA replication. In this video, the Amoeba Sisters discuss types of mutations, including insertion, deletion, and substitution mutations.