Deletion (DNA Mutation) — Definition & Examples

Deleting Parts of DNA

Deletion is a genetic mutation that can result in some seriously bad effects. During DNA replication, deletion is when a section of the DNA sequence is lost. Deletions can range from a single nucleotide to an entire section of a chromosome.

You will only notice deletions if they occur in a section of the DNA strand that produces a protein. Broken DNA doesn't really have any effects unless it is used to produce a broken protein.

A deletion error can happen for many reasons. It may be due to radiation, chemicals, or just a broken protein that fails to insert nucleotide bases.

Deletions and the Reading Frame

Deletion mutations are especially bad because they can disrupt the reading frame.

To create a protein, DNA is transcribed into RNA. The RNA is then turned into a protein by a ribosome. The ribosome reads groups of three nucleotides and, using tRNA, adds the matching amino acid on to the chain. If even one base pair is deleted, it can cause all amino acids that come after it to be different. This results in an entirely different protein than the desired one.

$$\text{AUGAACGAACUGUCU}$$

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.

$$\text{UGA/ACG/AAC/UGU/CU}$$

This new sequence would produce a very different protein.

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

What Are Deletion Mutations in DNA?

Deletion means exactly what you would expect—a nucleotide is deleted from a DNA sequence. Because DNA sequences are grouped into chunks of three called codons, deleting a nucleotide can throw everything off. Every codon following the mutation will not match the original DNA sequence.

Deletion 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 dangerous than a point mutation because it affects the entire DNA sequence after it. Frameshift mutations mean that the whole DNA sequence has shifted. The earlier in the DNA sequence that a frameshift occurs, the more messed up the protein will be.

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

$\color{#8925AE}{\text{Mutation}}$ : 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

(Video) Mutations in DNA

by Teacher's Pet

This video describes different types of DNA mutations, including point mutations, frameshifts, inversions, insertions, and deletions.

If a mutation happens in a non-coding region of DNA, it won't have any effect on the protein that is created.