GENETICS

Genetics or inheritance science is considered one of the most important branches of Biology.

We can describe genetics as a source of words and irritating terms for some people, and an interesting and fascinating hobby for others.

 This is the fact: if we want to know more about the miracle of mutations, we need to have the basic knowledge about genetics when we go deeper in birds breeding.

 The inheritance is controlled by a series of factors, nowadays called genes, which go from parents to children through the gametes.

 Every feature (eyes colour, plumage colour, sex, etc.) is determined by a pair of genes.

 If the genes of that pair are equal, the bird is called homozygous for this feature.

 If the genes of that pair are different, the bird is called heterozygous for this feature and the genes are called alleles.

MUTATION

 When a cellular division occurs in normal conditions, the genetic information pass without any alteration from cell to cell, from generation to generation.

 Before the cell is divided, each chromosome gives origin to other equal chromosome, with the genes in the same order, seeing that each DNA molecule produces an identical copy of itself.  

 When a cell is divided into two cells, the chromosomes come away form their   recently formed duplicates, and each one of the new cells get the same number and types of chromosomes and genes.

 This process of duplication of chromosomes and genes is precise, though we can commit an error. Due to a series of almost unknown reasons, a gene suffers a chemical alteration, so the new gene is not exactly equal to the previous one. A nucleotide is inserted instead of other, and it is suppressed from the DNA molecule. 

 Any of these situations modifies the nucleic acid molecule, stop being a copy of the original.  So, the written genetic message in the alphabet of the nucleotides it is modified.

This process of genetic changing, due to the alteration of a gene, is called genetic mutation.

This alteration produces a genotype (composition of the gene) completely different to the original phenotypes. The result can be a bird without survival conditions or a totally different healthy bird.

 When a bird acquires a new appearance (phenotype) and transmits its genetic code to the descendants, we are in face of the appearance of a new mutation.

 To conclude we can say that a mutation is a genetic deviation from the original form of the bird.

Type of mutations

Dominant: a dominant mutation is the one in which is only necessary a gene of the pair responsible for a specific characteristic, so that one bird shows the same characteristic in its phenotype.

 Recessive: a recessive mutation is the one that it is necessary that the pair of genes responsible for a determined characteristic it will be constituted by two equal genes, so that the bird can show the same characteristic in its phenotype.

 Sex-linked: a sex-linked mutation is the one that depends on the sexual chromosomes. This mutation has a dominant behaviour in the cocks and a recessive one in the hens.

 Co-dominant: an incomplete dominant or co dominant is the one in which the descendants present an intermediate phenotype in relation to its parents.

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Copyright © 2003 Viveiro Curval.
Actualizado: 08/17/03