Mutations
Mutation is a change in base pairs or nucleotide sequence of a genome. Errors that occur during DNA replication or even exposure to radiation can cause such changes in the DNA sequence. This change or mutation causes genetic variation, which eventually leads to evolution. The following are the different types of mutations –
Substitution
This mutation is caused due to chemicals or any errors in DNA replication. Typically, a purine is substituted with another purine or pyrimidine with another pyrimidine. This type of substitution mutation is called transition. If purine is substituted for a pyrimidine or vice versa, it is called transversion substitution.
Insertion
The addition of one or more nucleobases can cause this type of mutation. It can cause frameshift mutation or sometimes even alterations in the mRNA. Both will eventually affect the final gene product. Insertions are usually provoked by transposable elements (TE). Thus, removal of TE can reverse insertions.
Deletion
Removal of one or more nucleobases is called a deletion mutation. This mutation can also change the reading frame (frameshift mutation). Moreover, deletions are highly unlikely to be reversed. Examples of deletion mutation are Duchenne muscular dystrophy, male infertility, Cri du chat syndrome, cystic fibrosis, and spinal muscular atrophy.
Also Read: The Molecular Basis of Mutation
Difference between Substitution, Insertion and Deletion Mutations
| Substitution | Insertion | Deletion |
|---|---|---|
| It is a type of mutation where a nucleobase is replaced by another one. | It is a type of mutation where nucleotides are added/inserted into the DNA sequence. | It is a type of mutation where the nucleotides are removed/deleted from the sequence. |
| It causes base substitution or point mutation. | It causes frameshift mutation. | It causes frameshift mutation. |
Explore: Mutation- A Genetic Change
Frequently Asked Questions on Difference between Substitution, Insertion and Deletion Mutations
What are chromosomal translocations?
A chromosomal translocation leads to unusual arrangements of chromosomes. It is a type of large-scale mutation where the exchange of genetic parts between non-homologous chromosomes occurs.
What are transposable elements?
Transposable elements (TE) are a type of mobile genetic element that can move freely within a genome. TE are a sequence of DNA that can alter its position within the nucleotide sequence. They can create as well as reverse mutations.
What is deletion mutation?
An absence of a portion of a DNA molecule during DNA replication results in a deletion mutation. This uncopied portion can range in size from a single nucleotide to an entire chromosome. A genetic disorder may result from the loss of DNA during replication.
Duchenne muscular dystrophy, male infertility, Cri du Chat syndrome, cystic fibrosis, and spinal muscular atrophy are a few genetic disorders that can result from deletion mutations.
Define insertion mutation.
An insertion mutation, also referred to as a DNA insertion or gene insertion, is a form of mutation in which extra nucleotides are inserted into the DNA. Frameshift mutations include insertional mutations.
Examples of disorders brought on by insertional mutations include Cystic fibrosis, Myotonic dystrophy, Huntington’s disease, and Fragile X syndrome.
What is a frameshift mutation?
A frameshift mutation is typically caused by the deletion or insertion of nucleotides. This mutation shifts the reading frame, and thus alters the grouping of codons. A reading frame is nothing but the division of nucleotides into a triplet sequence.
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