1. Some helpful definitions
Somatic cell
any cell forming the body of an organism
diploid
Germ cell
gametes – sperm and ova
haploid
Sexual reproduction
the creation of offspring from two parents
results in a unique combination of genes inherited from the mother and the father
consists of two phases – mitosis and fertilization

3. Human Genome

5. More helpful definitions
Diploid
two copies are present of each chromosome
each chromosome has its homologous partner present
somatic cells are diploid
2n = 46 (humans)
Haploid
One copy of each chromosome present
Germ cells are haploid
n = 23 (humans)
Autosome
Non-sex chromosome
Chromosomes 1-22

6. Meiosis
The process that transforms 1 diploid cell into 4 haploid cells
First described in sea urchin eggs
Required for sexual reproduction:
Keeps the chromosome number the same after fertilization
Introduces genetic variation through recombination