Understanding Autosomal Genetic Disorders: Chromosomes & Phenotype

1. 7.1 Chromosomes and Phenotype: Autosomal Genetic Disorders 2.1 Atoms, Ions, and Molecules Set up Cornell Notes on pg. 81 • Topic: 7.1 Chromosomes and Phenotype: Autosomal Genetic Disorders • Essential Questions: • Why is it impossible to have a “carrier” of an autosomal dominant disorder? • Why is it impossible to have a “carrier” of an autosomal dominant disorder? KEY CONCEPT The chromosomes on which genes are located can affect the expression of traits.

2. P. 80 Video Notes Autosomal Recessive Disorder Albinism Treacher-Collins Syndrome

3. KEY CONCEPT The chromosomes on which genes are located can affect the expression of traits.

4. Many human genetic disorders are caused by autosomal genes, and can be predicted the same as flower color, or Pea shape • Autosomal genetic disorders: disorders that have no relation to the sex of an individual • Can be male or female in equal proportions Ex: Albinism

5. Any offspring with two recessive genes (cc) will have the disease/disorder C c Ex: Cystic Fibrosis Cc CC C cc c Cc

6. A carrier is heterozygous (Cc) for a recessive disorder and does not show any signs or symptoms, but can pass on the disorder to their offspring • Please label each box with: Carrier/Disorder/Normal C c Ex: Cystic Fibrosis Cc CC C *carrier Normal cc c Cc Disorder *carrier

7. Video: Autosomal Recessive Disorders (4m52s) Pg. 80 Take at least 10 bullets

8. Albinism is a autosomalrecessive disorder characterized by a lack of pigment in skin, hair, and eyes (race/gender does not matter!!!!) • Can affect ANY animal in the animal kingdom

12. mom mom A a A a dad dad a a A A Genotype: Phenotype: Carriers?: Albinism?: Are either of the parents albino? Genotype: Phenotype: Carriers?: Albinism?: Are either of the parents albino? Please label: normal/carrier/disorder

13. A a A a AA a a aa *disorder A A Aa *carrier Aa *carrier AA Aa *carrier Aa *carrier aa *disorder Genotype: AA, Aa Phenotype: • O% albino • 100% non-albino Carrier?: 50% carrier Albinism?: 0% albino Parents?: Neither parent is albino Genotype: Aa, aa Phenotype: • 50% albino • 50% non-albino Carrier?: 50% carrier Albinism?: 50% albino Parents?: Father is albino

14. Both Mom and Dad have to either have the disorder or be carriersfor offspring to be affected with an autosomal recessive disorder!

15. Video: ABC’s Special Report: Albinism- Caught between light and dark (6m54s) • 5-7 bullets • NON TRADITIONAL NOTES • Social issues? • Physical/Health issues? • Any other notations you make

16. Autosomal DOMINANT Disorders: any offspring with a dominant allele will have the disorder • Dominant disorders are uncommon • No carriers! ( Hh- would show the trait) H h H *anywhere there is an H the child will have the disease h

17. Huntington’s disease is a autosomal dominant disorder in which nerve cells in certain parts of the brain waste away, or degenerate. The disease is passed down through families. Causes • Huntington disease is caused by a genetic defect on chromosome 4. The defect causes a part of DNA, called a CAG repeat, to occur many more times than it is supposed to. Normally, this section of DNA is repeated 10 to 28 times. But in persons with Huntington disease, it is repeated 36 to 120 times. • As the gene is passed down through families, the number of repeats tend to get larger. The larger the number of repeats, the higher your chance of developing symptoms at an earlier age. Therefore, as the disease is passed along in families, symptoms develop at younger and younger ages. HD brain Normal brain

18. H h Huntington’s Disease H Genotype: Phenotype: h *anywhere there is an H the child will have the disease

19. H h Huntington’s Disease Genotype: HH, Hh, hh Phenotype: 75% Huntington’s Disease 25% non-H’s D H Hh HH Disorder Disorder Hh h hh Disorder *anywhere there is an H the child will have the disease

20. Treacher Collins Syndrome is an autosomal Dominant disorder. It can lead to the person having no cheekbones or very small cheekbones (so the eyes droop), and they may also have a cleft palate, under developed ears, and an very small jaw.

21. T t Tt *disorder t t tt Tt *disorder tt Genotype: Phenotype: If Mom or Dad have the disorder 50/50 chance the offspring will also have the disorder. Genotype: Tt, tt Phenotype: • 50% will have TCS • 50% non-TCS

22. Video: Ashley’s Story- Treacher Collins Syndrome (5m11s) • 5-7 bullets • NON TRADITIONAL NOTES • Social issues? • Physical/Health issues? • Any other notations you make

23. How did Ashley inherit the disease if neither of his parents had it? • This condition is caused by a change in a single gene. The Treacher Collins syndrome gene is on chromosome 5. Over 50 different changes in the gene are known to cause Treacher Collins syndrome. • In about 60% of people with Treacher Collins syndrome the change in their gene happened for the first time in them. This means that there is little chance of this person’s parents or brothers or sisters having any children with Treacher Collins syndrome.In about 40% of people with Treacher Collins syndrome one of their parents also has the same gene chance.

24. 7.1 Chromosomes and Phenotype: Sex-linked Genes 2.1 Atoms, Ions, and Molecules Set up Cornell Notes on pg. 83 • Topic: 7.1 Chromosomes and Phenotype: Sex-linked Genes • Essential Questions: 1. Describe how Sex-linked genes are expressed differently in men than women. 1. Describe how Sex-linked genes are expressed differently in men than women.

25. Punnett Square work • 82

26. Gene expression is often related to whether a gene is located on an autosome or a sex chromosome • Sex chromosomes: determine gender • Y chromosome genes in mammals are responsible for male characteristics. • X chromosome genes in mammals affect many traits. • Autosomes: all other chromosomes- no relation to gender • All genes that Mendel studied were autosomes • Most traits are the result of autosomal genes REVIEW

27. Because the X and Y chromosomes have different genes, sex-linked genes have a pattern of expression that is different from autosomal genes • 25% will have white eyes as expected (similar to autosomal findings) • BUT ALL will be male! Crossing 2 heterozygous

28. Female mammals have an XX genotype. • Expression of sex-linked genes is similar to autosomal genes in females. X X A A X X A a *carrier a X X a *disorder

29. Males have no second copies of sex-linked genes, so ALL of a male’s sex-linked genes are expressed • Even if all the sex-linked genes of a male are recessive, they will be expressed • There is no second “X” to mask the recessive gene X Y A X Y a *disorder

30. A Genes on sex chromosomes are called sex-linked genes. X A X • % chance of male offspring showing recessive trait? • % chance of female offspring showing recessive trait? A A A A A X X X X X A A Y X Y X Y

31. A Genes on sex chromosomes are called sex-linked genes. X A X • % chance of male offspring showing recessive trait? • 0% • % chance of female offspring showing recessive trait? • 0% A A A A A X X X X X A A Y X Y X Y

32. a Genes on sex chromosomes are called sex-linked genes. X A X • % chance of male offspring showing recessive trait? • % chance of female offspring showing recessive trait? A A A A a X X X X X a A Y X Y X Y

33. a Genes on sex chromosomes are called sex-linked genes. X A X • % chance of male offspring showing recessive trait? • 50% • % chance of female offspring showing recessive trait? • 0% A A A A a X X X X X a A Y X Y X Y

34. Examples of sex linked disorders • Color-blindness • Hemophilia • Muscular Dystrophy

35. Color blindness is a recessive sex-linked trait. A non-colorblind man marries a woman who is a carrier for color blindness. Predict the heredity of their offspring. (Use “b” to show color blindness) Phenotypes: Male- ______% colorblind ______% Non-colorblind ______% Carrier Female- ______% colorblind ______% Non-colorblind ______% Carrier

36. Color blindness is a recessive sex-linked trait. A non-colorblind man marries a woman who is a carrier for color blindness. Predict the heredity of their offspring. (Use “b” to show color blindness) B b X X Phenotypes: Male- 50% Colorblind 50% Non-CB NO CARRIERS Female- 0% Colorblind 100% Non-CB 50% carrier b B B B X X B X X X B X Y b X Y Y

37. Sex Linked Inheritance (5m15s) • https://www.youtube.com/watch?v=H1HaR47Dqfw

38. A white-eyed male fly mates with a red eyed female fly to produce: 24 white-eyed males, 27 white-eyed females, 26 red-eyed males, and 23 red-eyed females. Can this trait be sex-linked? Prove your answer by completing 2 Punnett squares. (r=white eyes) Phenotypes: Male- ____% Red eyes ____%White eyes Female- ____% Red eyes ____%White eyes

39. A white-eyed male fly mates with a red eyed female fly to produce: 24 white-eyed males, 27 white-eyed females, 26 red-eyed males, and 23 red-eyed females. Can this trait be sex-linked? Prove your answer by completing 2 Punnett squares. (r=white eyes) White eyes is a recessive sex-linked trait. R R X X Phenotypes: Male- 100% Red eyes 0% White eyes Female- 100% Red Eyes 0% White eyes R r r R X X r X X X R X Y R X Y Y

40. White eyes is a recessive sex-linked trait. A white-eyed male mates with a red eyed female to produce: 24 white-eyed males, 27 white-eyed females, 26 red-eyed males, and 23 red-eyed females. Can this trait be sex-linked? Prove your answer by completing 2 Punnett squares. (r=white eyes) R r X X Phenotypes: Male- 50% Red eyes 50% White eyes Female- 50% Red Eyes 50% White eyes R r r r X X r X X X R X Y r X Y Y

41. Sex Linked Genes (8m9s-10m17s) • https://www.youtube.com/watch?v=CBezq1fFUEA

42. Sex Linked inheritance Penny Lab Background The relationship between genotype and phenotype in sex-linked genes differs from that in autosomal genes. A female must have two recessive alleles of a sex-linked gene to express a recessive sex-linked trait. Just one recessive allele is needed for the same trait to be expressed in a male. Purpose To model the inheritance pattern of sex-linked genes based on probability Materials Coins (2) – prelabeled Genetic cross (given by teacher)

43. Sex Linked inheritance Penny Lab Procedure 1) One coin represents the egg cell and the other coin represents the sperm cell. In the Data/Results section of your lab, record the genetic cross you were given. 2) Fill in the Punnett square for the given genetic cross. 3) Determine the expected genotypic and phenotypic ratios. Use the key: A = does not have trait a = has the trait 4) Flip the two coins and record the genotype of the “offspring” in the count (tally marks) row of the data table under the appropriate given possible genotype. 5) Repeat step 4 until you have modeled 100 genetic crosses. 6) Calculate the total number of each genotype and the % of each type in your data table.

44. X chromosome inactivationrandomly “turns off” one X chromosome • Ensures that females, like males, have one functional copy of the X chromosome in each body cell • Like a flip of a coin to determine which “X” turns off P. 83

45. X Inactivation (6m22s) • https://www.youtube.com/watch?v=Y9vXhmI5FXM

46. X Chromosome inactivation example: • Tortoiseshell and Calico Cats (tend to always be female) • The female cats have white fur; and black (b)or orange fur (B) alleles on their X Chromosomes- these will be expressed randomly • Males have white fur; and one sex-linked gene for either black (b) or orange (B) fur X

47. B B R R Males only have one X chromosome so one color will be present Female cats have two X chromosomes. • Each patch of fur can be different depending on which X chromosome “turns off” R B B R X X X X X Y X Y X X B R B R

48. B X X B B R X X X-chromosome inactivation X R Black Y

49. B X X B B R X X X-chromosome inactivation X R Orange Y

50. B X X B B R B R X X X X X R Calico Calico B B X Y X Y Y Black Black