Genetic Mutations

Genetic Mutations

A genetic mutation is one that affects the chemical composition of a gene that is an alteration that occurs in the nucleotide sequence of DNA is that gene.

Gene mutations can be of several types:

 

 

OR SPECIFIC GENE MUTATIONS

Base substitution

A base is changed to another in the replication system. Enzymes copying on the DNA template, make a mistake and put the wrong base. Gene mutations by base substitutions are generally classified into two groups:

ü  Transitions, when a purine base is changed by another purine base or a pyrimidine for another pyrimidine.

ü  Transversions in which a purine is replaced by a pyrimidine or vice versa.

Addition or insertion base

Inserting a nucleotide sequence occurs in the gene, brought where there were correspondingly lengthening the chain.

Nucleotide deletion or loss

It is the loss of a segment of a chromosome and the chain is shortened by one.

 

Transposition or translocation base

 A DNA segment changes place. That is, a molecule fragment is broken and then binds but elsewhere. The displacement of the nucleotide chain sequences results in the appearance of new triplets which alter the genetic message.

MUTATIONS OR CHROMOSOMAL STRUCTURAL

They are those in which the change of genotype affects some chromosomal segment that includes more than one gene. Chromosomal mutations are caused by spontaneous rupture of the chromosomes. This phenomenon is sometimes increased by environmental conditions or by mutagens. They can be of several types:

 

DELETIONS: is the loss of a chromosome segment and therefore the loss of genetic information contained therein.

 

DUPLICATIONS: is the repetition of a chromosomal segment to a greater or lesser extent. The mirror may be on the same chromosome or in another. In humans, mutations of this type not known, this does not mean they do not occur but rather that affected individuals do not come to birth (spontaneous abortions).

 

INVESTMENTS: means breaking the chromosome by two points and the reversal of the fragment within the chromosome itself. Not often have negative or positive effects for the individual who suffers since no genetic information is lost, only changes of order. But it can cause the appearance of mutations in the gametes formed by the individual carrier.

TRANSLOCATIONS: A chromosomal segment changes position by moving to another part of the chromosome, his counterpart or any other chromosome. It may occur at the level of a single chromosome, that is, a fragment of a particular chromosome moves into another place, but within the chromosome itself.

 

GENOMIC MUTATIONS OR NUMERICAL

They are those that cause changes in the number of chromosomes characteristic of the species (karyotype). Always produce serious changes since each chromosome carries many genes. The most acceptable are those affecting small chromosomes. They can be of two types:

 

1. EUPLOIDÍA: The mutation affects the number of complete chromosome sets, ie the haploid number of species. An increase or decrease in the number of chromosome sets occurs.

 

2. ANEUPLOIDY: These are mutations that affect the number of chromosomes of an individual, but not the complete set of chromosomes, but individual chromosomes, ie chromosomes that exist more or less.

Bibliography:

AURORA APARICIO MANRIQUE. (S/f). Mutations. 05/10/15, de biology 2 website: http://ies.rosachacel.colmenarviejo.educa.madrid.org/aurora.pdf

Jose s. ramil. (S/f). Mutations. 12/10/15, de ciencias Sitio web: http://www.tirsoferrol.org/ciencias/pdf/a10_mutacion.pdf

Paola Cerruti Mainardi. (2006). Orphanet Journal of Rare Diseases. BioMed Central, 33, 1-9.

Enrique Gómez Galán. (S / F). Turner syndrome. 23.10.15, Spanish Association of Pediatrics Website: http://www.spao.es/documentos/biblioteca/entrada-biblioteca-fichero-60.pdf

Health Secretary. (2007). National Center for Gender Equity and Reproductive Health. 30 / October / 2015, of Children's Rehabilitation Center Telethon, the Group of Birth Studies AC, John Langdon down Foundation, AC Website: http://www.salud.gob.mx/unidades/cdi/documentos/Sindrome_Down_lin_2007.pdf