1. HEREDITY Chapter 4 Why do we look like we do?

2. 1.Describe your understanding of where genes are located and how they are passed on to offspring. 2.Explain your understanding of DNA, its base pairs and how it replicates. 3.Demonstrate your understanding through various genetic problems.

3. Opening Tasks 3/4/08 Write down two facts you know about genetics. 3/5/08 Which scientist led us to understanding genetics? Where are your genes located? 3/6/08 What are dominant and recessive traits? 3/7/08 What are phenotype and genotypes? 3/10/08 We use a _________ __________ to figure out offspring.

4. Gregor Mendel 1822-1884 Austrian Monk

5. PRINCIPLES OF HEREDITY  Mendel’s research led to our understanding of genetics. The genetic code DNA, determines all our traits inherited from our parents. These traits are passed on by genes which are located on the chromatids in the nucleus.

6. Mendel’s Experiment  P generation = parents  F1 generation are the offspring of the parents (kids)  F2 generation are the offspring of the F1 generation  Trait is a characteristic passed on to the offspring like height.  Traits are controlled by the alleles inherited from the parents  Alleles are different forms of a gene, for example the gene for height has 2 alleles – tall and short.

7. Inheritance Patterns

8. Genotypes  Show the combination of genes that are specific for all traits.  Recessive traits - symbolized by lower case letters, tt.  Dominant traits - capital letters, TT. One letter from each parent.

9. Phenotypes  Phenotypes show your physical characteristic:  Height  Eye  Hair color  Skin color.  In each pair of genes:  one comes from the mother  the other comes from the father.

10. Punnett Square  Used to help solve genetics problems

11. Punnett Squares  These can be used to show the probability of specific traits showing up in the offspring. For Example, sex of the child  X X  X  Y  XX = mother; XY = father genotyoes, now bring the letter over the box into the boxes under it.

12. Practice  Write mom XX; dad XY  Now draw a square like the last slide and place mom’s traits over the top 2 boxes and dad’s traits next to the boxes on the side.  Start with mom and the first X, bring it down & write it into each box it’s over. Do the same for the second X.  Repeat this for dad’s traits bringing each trait across into the boxes it’s next to.  Let’s do some others.

13. Cell division of the sex cells that form gametes. Parent cell has 23 pairs of chromosomes The chromosomes duplicate in the first stage

14. Chromosomes duplicate giving 46 pairs Cell divides into 2 cells with half the number of the previous cell. Each has the original number. 23 pairs After the final division 4 gamete cells are formed with ½ the number of chromosomes as the parent. Gametes are the egg cells in females and the sperm cells in males. Fertilization of the egg and sperm form a zygote.

15. The father determines the sex of the child because he passes on the Y chromosome. Remember mom is XX and dad is XY, therefore Mom can only pass on the X.

16. These traits can be passed on by mom only. The reason for this is only the X chromosome carries traits. Baldness, colorblindness & hemophilia are examples of these traits.

17. Research a genetic disorder and make a 2 sided informational brochure on the particular disorder you’ve chosen. This should include the following: Description of the disorder How it is passed on, from mom or dad? What are the limitations for the person affected by the disorder? What is the life expectance for this person? Include a picture if possible.

18. Complete the Missing Children Genetics Mystery. You will use information given to you about six children to try and match them up with the correct parents using what you’ve learned about genetics in this chapter.

19. Questions pg.116 #1-4 Questions pg. 120 #1-4 Check Your Knowledge pg. 132 #1-13 Make Connections pg. 133 #1 Face Lab – you need to do this with a partner. You also need paper and pencil.