Human Genetics BIO 392 NOTES

Human Genetics BIO 392 NOTES Chapter 14-1, 14-2

I. Human Genome A. General Information 1. ______base pairs a. 6 billion individual bases 2. “4 million pages” if the code were spelled out 3. Bases (letters) spell out genes (words) a. that result in the phenotype (the story) b. Some spell out bad stories: ______

B. CHROMOSOMES 1. Humans have 22 pair of ______2. Why is the 23rd pair different? ______3. What is the picture of the chromosomes called? ______4. When was this cell photographed? ______5. Is this a man or a woman? How do you know? ______C. X-linked Disorders 1. h = hemophilia, a sex-linked disorder

Is the dad affected?

Is the mom affected?

How many children have the disease?

How many children are carriers?

How many children are healthy? (careful!)

Is the dad affected?

Is the mom affected?

How many children have the disease?

How many children are carriers?

How many children are healthy? (careful!)

II. Studying Genetics A. Pedigrees 1. Another way to study inheritance 2. What do you think the dots in the F1 generation (line II) mean for offspring #2 and #5?

3. Can you draw the Punnett Square for the Parent generation? (I) 4. How to read a pedigree…

5. Pedigrees show ______6. Based mostly on ______7. Show the actual offspring a. Punnett squares show the ______offspring 8. Really only works well for ______a. Not polygenic traits 9. Only works for inherited traits a. ______play a large role in who we are

B. Inheriting Diseases 1. Just like physical traits, some ______can be inherited on our chromosomes. 2. And, just like physical traits, some are : a. ______b. ______c. ______d. ______III. Other Chromosomal Activity ______à if men only need one X chromosome, do women need both X’s? If not, which one “works”? ______à how gametes can end up with the wrong # of chromosomes in meiosis A. X-Chromosome Inactivation 1. Men are XY: one X chromosome is enough 2. Women are XX: The “extra” copy is not needed. a. It condenses into a ______3. Remember, you have trillions of cells. a. Which X chromosome that “switches off” can vary in each cell! 4. Mosaicism

B. Nondisjunction 1. ______2. Homologous chromosomes ______in meiosis 3. Result in ______or ______4. Examples: a. Klinefelter syndrome (trisomy X) b. Down syndrome (trisomy 21) c. Turners syndrome (X_ monosomy)