Meiosis 2n n n = number of chromosome Diploid: cells that have two copies of every chromosome Haploid: cells that have one copy of every chromosome Meiosis 2n n n = number of chromosome Diploid: cells that have two copies of every chromosome Haploid: cells that have one copy of every chromosome

Definition n Meiosis is a process that produces new gametes from somatic or body cells. –New cells are called sex cells n Gametes (sperm and egg cells) –Somatic cells are all cells in the body but gametes

Sex Cells n Sex cells have only 1/2 the number of chromosomes. 1 chromosome from each pair.

n Human body cells have 46 chromosomes (23 homologous pairs). n Homologous chromosomes contain the same genes at the same locations on the DNA Homologous Chromosomes

Autosomes and Sex Chromosomes

n Each pair contains 1 chromosome donated by the mother and one donated by the father. Inheritance of Homologues

Homologues Share Genes n A homologous pair of chromosomes contain all of the same genes. –Homologous pairs may contain different versions of genes called alleles.

Crossing Over n Homologues exchange alleles to randomize inheritance of genes during meiosis n Genes are not inherited together because they are on the same chromosoe n Each gene is inherited independently

Homologues Seperation n During Meiosis, one of each chromosome pair (homologues) ends up in a sex cell.

Meiosis vs. Mitosis n