Mutation is any alteration or variation in the genetic code; that is, an alteration of the genes of the chromosomes. It is possible for a mutation to occur while meiosis is taking place.
This variation can occur in somatic cells or in sex cells (gametes). If the mutations occur in the DNA of gametes, they can be passed from one generation to another. On the contrary, if it is produced in somatic cells, it will not be inherited, but it can be propagated asexually, which happens in plants (for example, those that reproduce by cuttings).
Mutations can occur spontaneously or induced by some agents called mutagens, they are classified as external and internal. External agents can be ultraviolet radiation, X-rays, changes in temperature, certain chemical substances, among others. Internal agents are accidental changes in the DNA code or the absence of sectors of the gene or chromosome.
Some mutations are harmless or silent, others are lethal; that is, they can cause the death of the embryo or a young individual. There are also mutations that can signify a step in the evolution of a species. Sometimes mutations help a species adapt better to a certain environment, but most of them hinder the survival of the species.
Mutations are classified as point and chromosomal. The former are a type of mutation capable of producing changes in the nucleotide sequence of DNA, causing modifications in the transcription of mRNA, and as a consequence, altering protein synthesis.
These changes can be by: addition (incorporation of one or more nucleotides); duplication (incorporation of a repeating nucleotide into a triplet); elimination (loss of one or more nucleotides) and substitution (change of one or more nucleotides for others that do not correspond).
Chromosomal mutations occur when there are changes in the structure of chromosomes, which can occur due to: deletion (loss of a portion of the chromosome); duplication (a portion of the chromosome is duplicated); inversion (a portion of the chromosome is reversed) and translocation (exchange of genetic material between non-homologous chromosomes).
They can also occur due to the change in the number of chromosomes, where two main types are distinguished: aneuploidy , characterized by the addition or loss of a chromosome (Down syndrome, Turner syndrome, etc.). And polyploidy is characterized because it involves the complete number of chromosomes of a species. In this case, each chromosome can multiply several times giving rise to 3, 4, 6 or more sets of chromosomes. This type of mutation happens more often in vegetables.
