Aim: How does sexual reproduction occur?

Look at the end result and what’s inside!!

MEIOSIS Produces daughter cells that have half the number of chromosomes as the parent cell.

Meiosis enables organisms to reproduce sexually. Gametes (sperm and eggs) are haploid.

Gametogenesis Cell division that produces gametes

Meiosis involves two divisions producing a total of four daughter cells

2 stages: Meiosis I, Meiosis II 1 2 4 cells with half the normal # of chromosomes 2 stages: Meiosis I, Meiosis II 23 23 23 MEIOSIS II 46 MEIOSIS I 23 23 23

Meiosis I Contains all phases of mitosis (IPMAT)

Meiosis II No interphase (PMAT) No replication of chromosomes

Meiosis in males Spermatogenesis All 4 new cells become sperm cells Testes

Meiosis in females Oogenesis (in ovaries) 1 egg, 3 polar bodies (break down) Meiosis in females

The polar bodies eventually disintegrate, leaving 1 ovum cell (egg) with haploid chromosomes. In oogenesis, 4 daughter cells are produced, but 3 are a lot smaller. We call them polar bodies. This normally happens once a month.

So, what is the difference between mitosis and meiosis?

Mitosis produces 2 identical daughter cells with the same number of chromosomes as the parent. Meiosis produces 4 haploid cells (half the number of chromosomes as the parent it came from).