Y12 Genetic Variation 1 - Genes to Meiosis

Diploid

Full chromosome number. E.g. 46 single chromosomes in humans - 2n (SOMATIC CELLS)

Haploid

Half chromosome number - 23 single in human GAMETE CELLS. - n

homologous chromosomes

Exactly same chromosomes, with same genes in same position on chromosome - 1 from mum/dad

Locus (loci)

Place on a chromosome where particular gene is found for a TRAIT (characteristic)

Gene

Section of DNA

Allele

An alternative form of a gene.

Centromere

Place where 2 chromatids are joined

Chromatid

one half of a duplicated chromosome

Somatic mutation

A mutation that occurs in the body cells. Cannot be inherited.

Gametic mutation

A mutation in the sex cells. Can be inherited.

Duplication mutation

a type of chromosomal mutation in which a segment of DNA is copied multiple times in the genome

inversion mutation

A genetic mutation in which the order of a segment of genetic material is reversed. This type of mutation can involve a small number of nucleotides as well as larger sections of a chromosome containing more than one gene

Translocation mutation

mutation in which one part of one chromosome breaks off and attaches to another

Mutation

A random, permanent change in the base sequence of DNA to produce new alleles

Autosome

All non-sex chromosomes in a cell

Bivalent

a pair of homologous chromosomes

Independent assortment

Random lining up of homologous chromosome pairs on the equator of a cell during meiosis 1st division. Producing lots variation in gametes made.

Crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Recombination

The genetic process by which one chromosome breaks off and attaches to another chromosome during meiosis I - cell division in gametes.

Segregation

2nd stage of division chromosomes separate (and so do the alleles). Each gamete has single allele for each trait - unique mixture of alleles.