Chapter 5 Section 2- Sexual Reproduction
A. Sexual Reproduction- two sex cells, usually an egg and a sperm, come together
a. Fertilization – the joining of an egg and a sperm, generally from two
different organisms of the same species
i. Sperm- are formed in the male reproductive organs
ii. Eggs- are formed in the female reproductive organs
iii. A cell that forms from fertilization is a zygote.
b. Following fertilization, Cell Division begins and a new organism
develops.
c. Human body cells are diploid, because they have 23 pairs of similar
chromosomes
d. Human sex cells are haploid, because they have 23 single chromosomes.
B. Meiosis- a process that produces haploid sex cells and ensures that offspring have
the same diploid number as its parent
a. In meiosis I, the nucleus divides and produces two new cells with one
duplicated chromosome each
b. In meiosis II, the nucleus divide and the chromatids separate, producing
four cells with half the number of chromosomes of the original nucleus