Acheived points biology genetic variation and change.

Linked genes

Genes that are inherited together with the other genes as they are located close together on the same chromosome.

Crossing over

A process occuring during meiosis where two chromosomes pair up and exchange segments of their genetic material.

Indipendant assortment

The process of random segrigation and assortment of chromosomes during meiosis resulting in the production of genetically unique gametes.

Mutations

A perminant change in the base sequence of the DNA.

Genetic drift

A change in the frequency of an existing gene of an existing variant in a population due to random chance.

Founder effect

A small group of population becomes seperated causing loss of variation.

Somatic mutation

A change in the DNA sequence that occurs in body cells in body cells. Will not be inherited by offspring.

Gametic mutation

A change in the DNA sequence that occurs in the sex cells and is therefore inherited by offspring.

Gene pool

Total sum of different alleles in an interbreeding population.

Allele frequency

The percentage of a population of a species that carries a specific allele on a given chromosome.

Natural selection

Organisms that are better adapted to their enviroment tend to survive and reproduce offspring with the beneficial traits.

Unlinked genes

Genes that are located on different chromosomes or are far apart from each other on the same chromosome.

Genetic variation

Variation in the allele frequency or the genome between members of species, or between groups of species.

Harmful mutation

A change in the DNA sequence that has a negative effect on the organisms health and survival.

Complete dominance

Type of inheritance where one allele completely masks the effect of another in a heterozygous individual.

Incomplete dominance

Neither trait / allele is completely dominant over the other, insted shows a blend of both parental traits.

Multiple alleles

Three or more alleles for a particular gene. The presence of multiple alleles is best illustrated by the ABO blood group of humans.

Meiosis

The process of cell division in sexually reproducing organisms that reduces the number of chromosomes in reproductive cells from diploid to haploid.

Segregation

The seperation of paired alleles of homologous chromosomes, especially during meiosis, so that the members of each pair end up in different gametes.

Homologous chromosomes

Pairs of matching chromosomes, one inherited from each parent, that contain the same genes in the same order, but potentially different alleles.

Bottleneck effect

An extreme example of genetic drift that happens when the size of the population is severley reduced and leads to loss of genetic diversity.

Co-dominance

A condition in which an individual who is heterozygous will express the phenotype associated with both alleles.

Sex linked gene

Gene located on the 23rd, X or Y chromosome.

Lethal allele

An allele that causes an organism to die when it's spesent in the homologous condition.