1. Inheritance

2. The Body Forms 2 Types of Cells:
1. somatic cells, or body cells, have 2 of each kind of chromosome (a pair)
the pair of chromosomes are called homologous because they carry the same traits
these cells are diploid (2n)

3. 2. sex cells, or gametes, have only one of each chromosome
these cells are haploid (n)

4. There are 2 Types of Cell Division:
mitosis produces somatic cells
2 daughter cells are identical to parent
all cells are diploid
takes place in most body cells
needed for growth and repair

5. meiosis produces sex cells
parent cell divides 2 times
produces 4 unique daughter cells
daughter cells are haploid

6. meiosis, cont. takes place in only 2 organs:
in females (♀), eggs are produced in the ovaries (oogenesis)
in males (♂), sperm are produced in the testes (spermatogenesis)

7. sexual reproduction involves the production and fusion of sex cells
when a sperm fertilizes an egg, a zygote is formed

8. Stages of Meiosis
Interphase
cell is growing
DNA replicates

9. Meiosis I
Prophase I
homologous chromosomes pair up (synapsis) and form a tetrad
sometimes non-sister chromatids exchange genetic information during crossing over

10. crossing over increases genetic variation

11. Meiosis I
Metaphase I
tetrads line up

12. Meiosis I
Anaphase I
homologous pairs are split up

13. Meiosis I Telophase I/ Cytokinesis 2 haploid nuclei are formed
2 daughter cells still contain sister chromatids
Interkinesis
break period between the 2 divisions

14. Meiosis II
Prophase II
a new spindle forms

15. Meiosis II Metaphase II
each chromosome lines up at the midline of the cell

16. Meiosis II
Anaphase II
the sister chromatids are separated and move to opposite ends of cell

17. Meiosis II Telophase II two new nuclei are formed
each nucleus contains a haploid(n) number of chromosomes
Cytokinesis
the end result of meiosis is 4 haploid daughter cells