Selective Breeding (Higher Biology)

[_sophie_]

Doing a revision mindmap on evolution and I have come across selective breeding in my notes..
'When selective breeding is used strains are formed by inbreeding - mating of genetically similar individuals. As each generation is formed the strains have a higher degree of homozygosity (many genes have identical alleles at each locus'

.... Sorry what?! Please translate into baby language.. what's a strain? And remind me of homozygosity? Getting myself really confused at the moment!

[DTCwordfan]

homozygous
In a living organism, having two identical alleles for a given trait. Individuals homozygous for a trait always breed true; that is, they produce offspring that resemble them in appearance when bred with a genetically similar individual; inbred varieties or species are homozygous for almost all traits. Recessive alleles are only expressed in the homozygous condition. Heterozygous organisms have two different alleles for a given trait.

Wilkipedia is not bad:
An allele (pronounced /ˈæliːl/ (UK), /əˈliːl/ (US); from the Greek αλληλος allelos, meaning each other) is one of two or more forms of the DNA sequence of a particular gene.[1][2] The word is a short form of allelomorph ('other form'), which was used in the early days of genetics to describe variant forms of a gene detected as different phenotypes.

Each gene can have different alleles. Sometimes, different DNA sequences (alleles) can result in different traits, such as color. Sometimes, different DNA sequences (alleles) will have the same result in the expression of a gene.

Most organisms have two sets of chromosomes, that is, they are diploid. These chromosomes are referred to as homologous chromosomes. Diploid organisms have one copy of each gene (and one allele) on each chromosome. If both alleles are the same, they are homozygotes. If the alleles are different, they are heterozygotes.

A population or species of organisms typically includes multiple alleles at each locus among various individuals. Allelic variation at a locus is measurable as the number of alleles (polymorphism) present, or the proportion of heterozygotes (heterozygosity) in the population.

For example, at the gene locus for ABO blood type proteins in humans,[3] classical genetics recognizes three alleles, IA, IB, and IO, that determines compatibility of blood transfusions. Any individual has one of six po

[_sophie_]

Thanks it's so confusing like a new language haha! It has made it a bit clearer though.. now whats a strain?!

[DTCwordfan]

A strain is a genetic variant or subtype of a microorganism (e.g. virus or bacterium or fungus). For example, a "flu strain" is a certain biological form of the influenza or "flu" virus.

[_sophie_]

Ok so is this right:

When selective breeding if formed.. lets say for example to produce a dog good for herding sheep (sheepdog)... when you breed the two parents together (sheepdog x sheepdog), some of the offspring will vary from the others.. lets just say 3 of them are good at herding and 1 is not so good.. is this 1 thats not good at herding the strain?!
Sorry and thanks!

[Mosaic]

Or horses - breed in (racehorse + racehorse who might already be close relatives) for more speed, breed out to add strength and stamina.

[DTCwordfan]

or the royal family.....descendant of Queen Victoria marries descendant of Queen Victoria to breed out any innate intelligence - with the benefit that they are incapable of meddling in affairs of state. Queen Anne being the last in 1708, I believe to use the deny royal assent to legislation.