Meiosis Page 64 - 65

Cell Cycle & Reproduction Sexual reproduction results in offspring that inherit genetic information from two parents. Sexual reproduction is more time consuming (finding a mate, growth & development of offspring), but it provides genetic diversity, which is an advantage when conditions change.

Organisms have pairs or sets of chromosomes (so humans have 2 sets of 23 chromosomes)

Important Vocabulary Homologous chromosome – pair of identical chromosomes Autosomes-Chromosomes not sex determining. Sex chromosomes- determine sex

4 . Diploid – When a cell had both sets of chromosomes it is a diploid cell.=2n 5. Haploid -When a cell only has one or half set of chromosomes it is a haploid cell. n

Mitosis # of divisions 1 Type of cells somatic Sets of chromosomes 2 (Diploid) # of cells 2 Resulting cells: Identical Stages Prophase, Metaphase, Anaphase, Telophase

Meiosis Meiosis is how gametes or haploid cells divide (it is how egg and sperm cells are created). There are 2 divisions, resulting in 4 unique cells. This is the basis for gentic diversity.

Meiosis 1 Meiosis 1: Stages Prophase I, Metaphase I, Anaphase I, Telophase I , Cytokinesis Crossing Over Exchange of segments of DNA between homologous chromosomes (During prophase 1) Independent Assortment Random assortment or lining up of chromosomes during metaphase 1.

Draw and label crossing over (pg 190)

Meiosis 1: Draw and label the stages of meiosis 1 (pg 174)

Meiosis 2 Meiosis 2 DNA DNA is not copied between meiosis 1 and 2. This is how haploid cells are formed. Stages Prophase 2, Metaphase 2, Anaphase 2 and Telophase 2 , Cytokinesis Gamete formation There are differences between the development of egg and sperm cells.

Draw and label Meiosis 2 on page 175

Mitosis vs. Meiosis Mitosis Meiosis

Compare / Contrast Mitosis and Meiosis # of divisions 1 2 Type of cells somatic gametes Sets of chromosomes 2 (Diploid) 1 (haploid) # of cells 4 Resulting cells: Identical Unique Stages Prophase, Metaphase, Anaphase, Telophase Prophase 1, Metaphase1 , Anaphase1 , Telophase1, Prophase 2, Metaphase 2 , Anaphase,2 Telophase2