What are we learning today?

1.What are the phases of meiosis and what happens during each phase?

2.What is the significance of meiosis to sexual reproduction?

What are we learning today?

1.How are mitosis and meiosis similar?

2.How are mitosis and meiosis different?

Meiosis

Cell basics• Somatic cells :

have two sets of chromosomes.

• One from each parent.

• Includes all cells in your body except gametes

• Somatic cells are diploid.

Cell basics• Diploid : contains

two sets of chromosomes

• The two chromosomes in each pair are called homologous.

• Humans have 23 pair of homologous chromosomes.

Cell basics

• Autosomes : all chromosomes in the cell except the sex chromosomes X & Y

• Humans have 22 pair of autosomes and 1 pair of sex chromosomes.

Cell basics

• For reproduction to occur, the chromosome number must be reduced by ½.

• Remember, in a somatic cell, one chromosome came from each parent

Meiosis• Meiosis : cell

division which results in the production of gametes with half the number of chromosomes

• When fertilization occurs, the zygote will contain the full set of homologous chromosomes

Meiosis

• The cells produced from meiosis are haploid• Haploid : cells with one copy of each

chromosome.• Gametes are haploid.

Meiosis

• The phases of meiosis are similar to mitosis

• Meiosis consists of 2 divisions of the cell.

• The result is four daughter cells.

Stages of Meiosis

• The stages of meiosis are named prophase, metaphase, anaphase, telophase

• The 2 cell divisions are distinguished by “I” or “II”

Result of Meiosis

• Four haploid cells called gametes

• Four daughter cells not identical to the parent cell.

• Gametes are necessary for sexual reproduction

What are we learning today?

1.What are the phases of meiosis and what happens during each phase?

2.What is the significance of meiosis to sexual reproduction?

What are we learning today?

1.How are mitosis and meiosis similar?

2.How are mitosis and meiosis different?