3. MEIOSIS: NON DISJUNCTION

Click here to view an animation on meiosis and the consequences of non disjunction.
Questions:
1. In this animation, when does non-disjunction occur?
2. What fails to separate in this animation?
3. If the the gamete producing cells has 4 chromosomes, how many chromosomes should each gamete contain?

2. MEIOSIS: NON DISJUNCTION

This website shows three animations: 1) crossing over, 2) normal meiotic division in females and fertilization, and 3) non disjunction in Down Syndrome. Also, click on the last box to view an animated power point on meiosis and fertilization.

Questions:
1. What is the difference between spermatogenesis and oogenesis?
2. In humans, how many chromosomes are present in the gametes?
3. In humans, how many chromosomes are present in somatic cells?
4. How do somatic cells divide?

1. MEIOSIS: NONDISJUCTION

Click here to watch an animation non disjunction during meiosis.

Questions:
1. In this animation, at what stage of meiosis does non disjunction occur?
2. What is the result of non disjunction?

MITOSIS vs. MEIOSIS

MITOSIS: is the reproduction of body cells (somatic cells), diploid, two daughter cells produced, chromosomes line up singly in metaphase, one nuclear division, produces cells for growth and repair, daughter cells have two sets of chromosomes (pairs), daughter cells are genetically identical to the parent cell

MEIOSIS: produces sex cells (gametes), haploid, four produced, two nuclear divisions, produces cells for sexual reproduction, daughter cells have only one member of each pair of chromosomes, daughter cells have one half of the genes from the parent cell, generates genetic diversity through crossing over and random seperation of homologous pairs of chromosomes.

2. MEIOSIS

Click here for a meiosis tutorial. Once you read about meiosis, you can scroll down and watch the animation on meiosis I and II.

How is meiosis different to mitosis?
What is the importance of crossing over?

1. MEIOSIS

Click here to watch a video clip on meiosis.
Questions:
1. How are the daughter cells compared to the parent cell after meiosis?
2. How many daughter cells are produced in meiosis?
3. What happens during prophase 1 between homologous chromosomes?
4. What are homologous chromosomes?