Answer the following question in a complete sentence.

A carrot cell contains 18 chromosomes. Which of the diagrams at the right illustrates the correct number of chromosomes in new cells produced by mitosis? How do you know?

Objectives:1)To describe the process of meiosis

2)To compare meiosis to mitosis

Meiosis

Mitosis ReviewThe process of cell divisionOccurs in somatic cells which are all the

cells in your body except egg and sperm cells

2N Diploid meaning that it has two of each chromosomeThese two chromosomes are identical in

mitosis

I. MeiosisA. Process of making sex cells called gametes

1. Male gametes are sperm2. Female gametes are eggs

B. Sex cells have half the number of chromosomes as other cells

1. N (haploid)

C. When sperm fertilizes egg zygote1. 2N (diploid) – it has 2 of each chromosome,

1 from mom, 1 from dad

II. Meiosis occurs in 2 divisionsA. Interphase I - Before meiosis, cells in testes/ovaries

copy DNA

B. Meiosis I1. Prophase I - Chromosomes with same type of genetic

information (homologous chromosomes) match up a. these chromosomes may “swap” genes

2. Metaphase I - Homologous pairs line up in middle of cell RANDOMLYRANDOMLY

3. Anaphase I - Pairs split up4. Telophase I – Cell membrane begins to pinch in and

results in 2 daughter cells are different from each other & parent cell

C. Between meiosis I and meiosis II, DNA does not copy again

D. Meiosis II is like mitosis1. Prophase II – new spindle fibers form

around the chromosomes2. Metaphase II - Chromosomes line up

in center of cell3. Anaphase II - Chromosomes split

apart & move into daughter cells4. Telophase II - End result: 4

daughter cells that are each unique

View meiosis

III. How does meiosis compare to mitosis?

A. Mitosis1. Replicate once,

divide once2. 2 daughter

cells are identical to parent cell

B. Meiosis1. Replicate once,

divide twice2. 4 haploid

daughter cells, not identical to parent or each other