GENETICS: TOUR OF THE BASICS

CLICK HERE to find out about DNA, genes, chromosomes, proteins, heredity, and traits.
1. Why do most offsrping tend to be a blend of the characteristics of both parents?
2. why do we say that genes come in pairs?
3. How do we get traits from our parents?

WHAT ARE GENES?

WHERE DO YOUR GENES COME FROM?

1. How do we call cells with the two sets of chromosomes?
2. How do we call cells with only one set of chromosomes?
3. Each trait is coded by one gene. How is each version of a gene called?
4. Why is crossing over important? when does crossing over occur?
5. How does the sygote develop into a multicellular organism?
6. what process enables us to receive one version of a gene from each parent?

TRANSPLANTS THAT DO THEIR JOB, THEN FADE AWAY

Click here to read an article from the New York Times about a promising surgery technique on liver transplant.

1. Why do transplant patients need to take immunosuppression drugs?
2. How do these drugs affect the patient?
3. Why/How are rejections caused?

THE MENSTRUAL CYCLE

Click here to access an animation on the menstrual cycle. On the website you should click on the slider bar, then hold down and drag your mouse back and forth to see fluctuations during the menstrual cycle.
1. What hormone does the ovary secrete that stimulates the production of the egg?

2. Why is the menstrual cycle said to be controlled by feedback mechanisms?

FEMALE REPRODUCTIVE SYSTEM

Click here to access a website about the female reproductive system. On the website, click on the diagram of the female reproductive system, and then if you click on each of the organs a bubble will appear with information about the organ.
1. What are the main female hormones?
2. What hormones stimulate the gonads to produce their hormones?

MALE REPRODUCTIVE SYSTEM

Click here to access a website with information on the male reproductive system.
On the website you will find links to articles with useful information on human general health. Which articles and pieces of information did you find more interesting?
1. Where does meiosis occur in males?
2. What is the product of meiosis in males?
3. What is the main hormone produced by the testicles?
4. What is the function of this male hormone?

5. Can you identify and describe the function of three organs of the male reproductive system?

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?