Why do some scientist feel that diarrhea is hereditary?

It runs in our “genes”/jeans

Cell Cycle including Meiosis(known as Gametogenesis)

Purpose:To create germ cells, gametes or sex cells.

- cells with ½ the number of chromosomes- known as 1N cells-two types of germ cells

-sperm -egg / ova

-in humans 1N/monoploid # =23-contains 1 chromosome from each of the

23 pairs.

Two types of gametes

Spermatogenesis:-meiosis that takes place in the testicles-produces sperm-made starting at puberty and ends at death-occurs everyday at a rate of 120 to 200 million/day

Male Reproduction

Oogenesis:-meiosis that takes place in the ovaries-produces ova/eggs-occurs:

-during 2nd month of fetal development-ova stored and released once a month during menstrual cycle -starting at puberty and ending with menopause

-each ovary contain approximately 300,000 eggs.

Female Reproductive

Gametogenesis1 parent cell divides twice creating four cells with ½ the number of chromosomes.

Parent cell is either a testicle or an ovary cells each starting with 46 chromosomes.

Meiosis I

Meiosis II

Interphase I

Occurs in testicle or ovary cell, 2N cells

DNA replicates

Prophase I1. Chromatin supercoils into chromatid2. Centrioles split and form spindle fibers3. Nucleus and nucleolus disassemble4. Homologous pairs of chromosomes pair up

Homologous Chromosomes

Chromosomes that carry the same set of genes.

One is from your mom and one from your dad.

Metaphase I1. Homologous pairs of chromosomes move

to the middle of the cells, each pair lines up on one spindle fiber.

2. Chromosomes line up randomly

Anaphase I1. Homologous pairs of chromosomes split

apart and move away to opposite sides of the cell.

2. Asters push against cell membrane causing the cell to elongate.

Telophase I with cytokinesis1. Nucleus and nucleolus reform2. Cell divides into two/cytokinesis3. End result is now 2 cells each with 23

replicated chromosomes each.

Interphase II

DNA does not replicate

The rest of meiosis II is identical to mitosis.

End result is four cells each with ½ the number of chromosomes.

Hyperlink