A mutation can be defined as any change in the genetic material of an organism.
This change can cause a corresponding change in the individual's phenotype.
Mutations can occur spontaneously or induced.
It spontaneously occurs due to errors in DNA replication. And in an induced way, when the organism is exposed to a mutagenic agent, such as radiation.
Mutations can occur in somatic or germ cells.
Mutation Types
Mutations can be of two types: genetic or chromosomal.
gene mutation
Gene mutation is characterized by changes in the code of nitrogenous bases in DNA, which give rise to new versions of genes. This condition can produce new characteristics in mutation carriers.
In gene mutation, substitution, deletion or insertion of one or more bases in the DNA chain can occur.
Types of gene mutations by:
- Replacement: exchange of one or more base pairs occurs;
- Insertion: when one or more bases are added to DNA, changing the reading order of the molecule during replication or transcription.
- deletion: occurs when one or more bases are removed from the DNA, modifying the reading order, during replication or transcription.
The gene mutation can also be from silent type. This mutation occurs when the replacement of a specific DNA nucleotide does not change the synthesized amino acids.
chromosomal mutation
Chromosomal mutation refers to any change in the number or structure of the chromosomes.
Chromosomal mutation can be of two types:
Numerical mutations: can be classified into aneuploidies and euploidies. Also called numerical aberrations.
- aneuploidy it occurs when there is a loss or addition of one or more chromosomes, due to errors in chromosome distribution during mitosis or meiosis. This type of mutation is responsible for cause disturbances and diseases in humans,çhow to Down's syndrome, Turner Syndrome and Klinefelter Syndrome.
- euploidy it occurs when there is a loss or addition of complete genomes. It arises when chromosomes duplicate and the cell does not divide. In this type of mutation, triploid (3n), tetraploid (4n) individuals can be formed, among other cases of polyploidy.
structural mutations: These are alterations that affect the structure of chromosomes, that is, the number or arrangement of genes on chromosomes.
They can be classified into some types:
- Deficiency or deletion: when a piece of chromosome is missing;
- Duplication: when the chromosome has a repeated piece;
- Inversion: when the chromosome has an inverted piece;
- translocation: when a chromosome has a piece from another chromosome.
Also read about Genetic variability.
