Sexual Reproduction and Meiosis Chapter 8 Section 2

Sexual Reproduction and Meiosis Chapter 8 Section 2 p. 218 -223

A. Sexual Reproduction n Two sex cells, usually an egg and a sperm, come together

A. Sexual Reproduction n 1. Fertilization- the joining of an egg and a sperm, generally from two different organisms of the same species

A. Sexual Reproduction n 1. Fertilization- the joining of an egg and a sperm, generally from two different organisms of the same species n a. Sperm are formed in the male reproductive organs

A. Sexual Reproduction n 1. Fertilization- the joining of an egg and a sperm, generally from two different organisms of the same species a. Sperm are formed in the male reproductive organs n b. Eggs are formed in the female reproductive organs n

A. Sexual Reproduction n 1. Fertilization- the joining of an egg and a sperm, generally from two different organisms of the same species a. Sperm are formed in the male reproductive organs n b. Eggs are formed in the female reproductive organs n c. The new cell that forms from fertilization is a zygote n

A. Sexual Reproduction n 2. Following fertilization, mitosis begins and a new organism develops.

B. Cell Division in sex cells n 1. Body cells are diploid because they have 23 pairs of chromosomes

B. Cell Division in sex cells 1. Body cells are diploid because they have 23 pairs of chromosomes n 2. Sex cells are haploid because they have 23 single chromosomes (half a set) n

3. Meiosis n The process that produces haploid sex cells

3. Meiosis n The process that produces haploid sex cells n a. In Meiosis I, the nucleus divides and produces two new cells with one chromosome each.

3. Meiosis n The process that produces haploid sex cells n n a. In Meiosis I, the nucleus divides and produces two new cells with one chromosome each. b. In Meiosis II, the nuclei divide again and the chromatids separate, producing four cells with half the number of chromosomes of the original nucleus.