Meiosis

Sexual Reproduction Requires 2 parents Sex cells have half the chromosomes as body cells When 2 parent sex cells combine, a body cell is produced and it has a full set of chromosomes Variety in offspring

Homologous Chromosomes In body cells chromosomes are found in pairs. The pairs are called homologous chromosomes (same structure and size). They carry the same genes (can be different versions of the same gene). Example: One chromosome pair is for sex chromosomes Females XX Males XY Cells with a pair of every chromosome are called diploid.

Sex Cells Sex cells are called gametes. Gametes have half the number of chromosomes. Gametes are haploid, meaning they have one chromosome from each homologous pair. Gametes are made in reproductive organs. Egg- female gamete Sperm- male gamete

Answer the question on p. 273

Meiosis The type of cell division that produces haploid sex cells When an egg is fertilized by a sperm cell, a new diploid cell forms. Meiosis makes 4 haploid cells Meiosis has 2 parts

Meiosis I Chromosomes are copied before meiosis I p. 274

Meiosis II The two cells made in meiosis I will divide in meiosis II The result is 4 haploid cells In males it’s 4 sperm cell and in females it’s 4 egg cells

p. 275

Mitosis vs. Meiosis Use the info on p. 276 to complete the chart.