Mutation

Mutation is a change in the genetic information within a cell.

Illustration of mutation

Mutation refers to any alteration in the genetic material of a cell, specifically in its DNA sequence. This change can occur naturally due to errors during DNA replication or induced by external agents. Mutations can lead to variations in the inherited characteristics of organisms and can play a pivotal role in evolution, but they can also result in genetic disorders or diseases.

Background

DNA (Deoxyribonucleic acid) carries the instructions necessary for the organism's development, function, and reproduction. A mutation alters these instructions, potentially affecting the organism's phenotype.

Types of Mutations

Mutations can be categorized based on various criteria, including their mechanism, impact, and location.

By Mechanism

• Base Substitution: Replacement of one base pair with another. Examples include transitions and transversions.
• Deletion: Removal of one or more base pairs.
• Insertion: Addition of extra base pairs.
• Frameshift Mutation: Resulting from insertions or deletions that aren't a multiple of three base pairs, disrupting the codon reading frame.

By Impact

• Silent Mutation: Changes a base but does not alter the amino acid in the protein.
• Missense Mutation: Changes a base resulting in a different amino acid in the protein.
• Nonsense Mutation: Introduces a premature stop codon, truncating the protein.
• Neutral Mutation: Doesn't result in a discernible impact on the organism's fitness.

By Location

• Gene Mutation: Occurs within a gene.
• Chromosome Mutation: Involves changes in the structure or number of whole chromosomes.
• Genome Mutation: Affects the number of DNA molecules in the cell.

Causes

• Spontaneous Mutations: Random errors during DNA replication.
• Induced Mutations: Caused by external agents known as mutagens.
• Chemicals: E.g., nitrosamines, benzopyrene.
• Physical: E.g., UV light, X-rays.
• Biological: Certain viruses or bacteria.

Impact on Health

While many mutations are harmless, some can be detrimental or even advantageous.

• Beneficial Mutations: Offer a survival or reproductive advantage.
• Harmful Mutations: Can lead to diseases or disorders. Examples include Cystic fibrosis, Sickle cell anemia, and certain cancers.
• Neutral Mutations: Have no immediate advantage or disadvantage.

Evolutionary Significance

Mutations are a primary source of genetic variation, crucial for evolution as they provide the raw material for natural selection.

See Also

• Genetic disorder
• DNA repair
• Genetic variation
• Oncogene