A mutation is an alteration, natural or induced by some mutagenic agent, that occurs in the genome (the organism's genetic material or virus). It can occur in both somatic and germ cells, and can thus be inherited.
Mutations are the main sources of genetic variability, directly influencing the evolution process of living beings. They can be classified according to the place where they occur and the effects they cause on a living being.
What is a mutation?
A mutation is a change that occurs in the genetic material of individuals. They can originate naturally, during the processes of mitosis, meiosis, or protein synthesis, or result from the action of some mutagenic agent. They can also occur at three levels:
Molecular: it can also be called a genetic or point mutation, as it affects a nucleotide or a group of nucleotides in the DNA;
Chromosomal: occurs in more than one gene, thus affecting the chromosome structure;
Genomics: alters the entire genome, affecting the total number of chromosomes or the chromosomes present in pairs individually. This type of mutation is responsible for causing some syndromes, such as Down syndrome.
How does it happen?
The mutation appears naturally or can be induced by mutagenic agents, that is, chemical or physical substances that can induce mutations, such as ultraviolet rays and X-rays, alcoholic beverages, substances derived from tobacco, as well as some medicines.
Mutations occur due to changes that arise in the nucleotides of DNA, which can occur through chemical changes in nitrogenous bases, errors in nucleotide incorporation (insertion of one nitrogenous base in place of another), addition or removal of nitrogenous bases, alterations in the structure and number of chromosomes, among other factors.
Often, some of these changes that arise are corrected before DNA replication. When that doesn't happen, a new molecule appears with the change, and it can reproduce itself.
Mutations can occur in somatic or germ cells. When they appear in somatic cells (cells in the body, except for the reproductive ones), they are generally not heritable and can cause problems such as the development of tumors, premature aging, malformations (when it occurs in the embryonic period), among others.
When they occur in germ cells (cells that give rise to gametes), these mutations are passed on to descendants, which can cause various genetic disorders, the emergence of syndromes, malformations, and abortion.
Types of mutations
Importance of mutations
Mutations are often related to something negative, mainly because they are linked to the emergence of some types of tumors and syndromes. However, mutations can create new alleles and new genes, contributing to greater genetic variability.
Genetic variability expands the capacity of populations to deal with environmental changes and is subject to natural selection, which will eliminate or preserve a certain phenotype (set of observable characteristics in an organism) generated by a certain genotype, being an essential factor in the evolutionary process.
Generally, when the mutation gives rise to a characteristic that confers a certain advantage on the individual, it is preserved. The species' genotype is the result of advantageous mutations, which were preserved over time by natural selection.
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