11.4 - Meiosis

Parents can produce many offspring. Families will have resemblances, but no two are exactly alike.

Every cell has a nucleus. Every nucleus has chromosomes. The number of chromosomes depends on the species. Humans have 46.

Genes are located on the chromosomes. Genes control the traits of the individual.

Chromosomes come in matching sets called homologous pairs.

Body cells have a complete set [46] - they are called diploid (2n). Sex cells only have half [23]  - they are called haploid (n).

When gametes combine, the zygote (offspring) gets full set of chromosomes – half from mom & half from dad. Zygotes are diploid.

The process of creating a gamete (sex cell) is called meiosis. It is similar to mitosis, but  will produce 4 daughter cells that are each haploid.

PROPHASE I of MEIOSIS homologous pairs match up which makes a tetrad   chromosomes then trade genes which is called crossing-over

crossing-over increases the number of possible gene combinations