Nuclear division of sex cells Meiosis Nuclear division of sex cells

Meiosis Two divisions of a single nucleus occur Produces gametes (sex cells) Eggs Sperm Fertilization- joining of sex cells Producing a zygote

Meiosis Because meiosis joins 2 cells, unlike mitosis that occurs in 1 cell Each sex cell should only contain 1 copy of each chromosome (23 total chromosomes….no pairs) So this is why nuclear division occurs twice This results in Meiosis 1 and Meiosis 2

Meiosis Produces gametes (sex cells) Interphase Time between cell divisions 3 phases G1 phase- growth S phase- DNA replicate creating a duplicate chromosome G2 phase- prepare to divide

Meiosis Meiosis- Prophase I Pairs of homologous chromosomes Remember each chromosome

Meiosis Meiosis- Metaphase I Homologous chromosome pair line up in the center of the nucleus

Meiosis Meiosis- Anaphase I Chromosomes separate and move to the opposite ends of the nucleus

Meiosis Meiosis- Telophase I and Cytokinesis I Chromosomes reach opposite sides of the cell New nuclear membrane forms The new nucleus each contains a chromosome with 2 chromatids The cell divides

Meiosis Meiosis- Prophase II No replication takes place Each cell contains one chromosome from the homologous pair

Meiosis Meiosis- Metaphase II Chromosomes line up in the middle of the cell

Meiosis Meiosis- Anaphase II Chromatids separate Move towards the poles (opposite sides of the nucleus)

Meiosis Meiosis-Telophase II and Cytokinesis II Nuclear membrane forms around the chromosome 4 new cells are formed each with half the number of chromosomes Example humans 23 chromosomes

Meiosis End Products 4 Daughter cells 23 chromosomes each Create either an egg or sperm cell