1. SECTION 6.1 CHROMOSOMES AND MEIOSIS

2. YOU HAVE BODY CELLS AND GAMETES  Somatic Cells  Definition: body cells; make up most of your body tissues and organs; DNA in body cells is not passed on to your offspring  Examples: spleen, kidneys, and eyes  Chromosome # (in humans): 46

3.  Gametes  Definition: cells in your reproductive organs; sex cells; DNA in gametes is passed on to your offspring  Examples: eggs in the female and sperm in the male  Chromosome # (in humans): 23

4. YOUR CELLS HAVE AUTOSOMES AND SEX CHROMOSOMES  Homologous Chromosomes  2 chromosomes (one from the mother and one from the father) that have the same length and general appearance  Have copies of the same genes, but the 2 copies may differ

5.  Autosomes  chromosome pairs 1-22; they contain genes for characteristics not directly related to the sex of the organism  Sex Chromosomes  chromosome pair 23; chromosomes directly control the development of sexual characteristics  Humans have 2 types of sex chromosomes: X and Y  Females = XX  Males = XY

6. Autosomes: pairs 1-22 Sex Chromosomes: pair 23

7. BODY CELLS ARE DIPLOID AND GAMETES ARE HAPLOID  Sexual Reproduction involves the fusion of 2 gametes, resulting in offspring that are a genetic mixture of both parents.  The actual fusion of an egg and a sperm cell is called fertilization.

8.  Diploid  Definition: a cell has 2 copies of each chromosome – one copy from the mom and one copy from the dad  Symbol: 2n  In Humans: diploid chromosome number is 46

9.  Haploid  Definition: a cell has only one copy of each chromosome  Symbol: n  In Humans: haploid chromosome number is 23  Each human sperm and egg cell has 23 chromosomes

11.  Meiosis  a form of nuclear division that divides a diploid cell into haploid cells  Essential for sexual reproduction because this is how sperm and egg are created

12. COMPARISON OF MEIOSIS AND MITOSIS