1. 1 Chapter 8- Mendel And Heredity

2. 2 C. Pedigrees

3. Symbols Pedigree Sample

4. Rather than manipulate mating patterns of people, geneticists analyze the results of matings that have already occurred. In a pedigree analysis, information about the presence/absence of a particular phenotypic trait is collected from as many individuals in a family as possible and across generations. The distribution of these characters is then mapped on the family tree. Pedigree analysis

5. For example, the occurrence of widows peak (W) is dominant to a straight hairline (w). The relationship among alleles can be integrated with the phenotypic appearance of these traits to predict the genotypes of members of this family. Pedigree analysis

6. Examples: Widow’s Peak & Earlobes

7. Is widow’s peak a dominant or recessive trait? Widow’s Peak No Widow’s Peak

8. Is an attached earlobe a dominant or recessive trait? Attached Earlobe Free Earlobe

9. D. Sex-Linked Traits

10. Sex-Linked Traits

11. 11 Color-Blindness

12. 12

13. 13

14. 14

15. What type of inheritance pattern? Color blindnessRed-Green

16. Queen Victoria Albert Alice Louis Alexandra Czar Nicholas II of Russia Alexis Hemophilia in the royal family of Russia

17. XNXN Y XNXN XnXn XNXNXNXN XNYXNY XNXnXNXn XnYXnY Hemophilia Example N = Normal Bloodn = Hemophilia

18. 18 III. Patterns of Heredity can be complex A. Traits influenced by several genes 1. When several genes influence a trait, the trait is said to be polygenetic.

19. Polygenic Inheritance Example Polygenic (multiple Genes) for a given phenotypic character. Example: Skin Color, Eye Color, Hair Color, & Rh Factor.

20. Polygenic Inheritance Example: Skin Color The melanin factor is located on three loci of each chromosome. (total of six locations)

21. Polygenic Inheritance: Human skin color is a good example of polygenic (multiple gene) inheritance. AABBCC Most Melanin aabbcc Least Melanin Assume that three "dominant" capital letter genes (A, B and C) control dark pigmentation because more melanin is produced. The "recessive"alleles of these three genes (a, b & c) control light pigmentation because lower amounts of melanin are produced.

22. Polygenic Inheritance Example Let’s do a cross. ABC A B C abc a b c X

23. 23 Polygenic Inheritance Example Result would be the F1 generation would be AaBbCc. abc ABC abc ABC abc ABC F1

24. Polygenic Inheritance Example Let’s cross the F1 with another F1. ABC a b c X ABC a b c

25. 25

26. Polygenic Inheritance Example F2 F1 F2

27. Gametes ABC ABc AbC Abc aBC aBc abC abc ABC65545443 ABc54434332 AbC54434332 Abc43323221 aBC54434332 aBc43323221 abC43323221 abc32212110 Polygenic Inheritance Example: Skin Color ABC/ ABC ABC/ ABc ABc/ ABc

28. 28 2. In some traits there is neither dominant nor recessive genes. These are called incomplete dominance. Example: Red flower RR and a White WW flower both with incomplete dominance will have pink flowers.

29. Incomplete Dominance Example X = Red Carnation White Carnation X = Pink Carnation

30. Incomplete Dominance with Snapdragons Flower Color P Generation F 1 Generation F 2 Generation Red C R Gametes CRCR CWCW  White C W Pink C R C W Sperm CRCR CRCR CRCR CwCw CRCR CRCR Gametes 1⁄21⁄2 1⁄21⁄2 1⁄21⁄2 1⁄21⁄2 1⁄21⁄2 Eggs 1⁄21⁄2 C R C R C W C W C R C W

31. 31 3. When two dominant alleles are expressed at the same time, both forms of the trait are displayed this is called co dominance. Example: Coat colors in a horse. 4. Genes with three or more alleles are said to have multiple alleles. Example blood groups ABO.

32. BW BW BW BW checkered chicken WW X BB BB W W BW Example of Codominance: In chickens, black feather color (BB) is codominant to white feather color (WW). Both feather colors show up in a checkered pattern in the heterozygous individual (BW). Cross a checkered chicken with a checkered chicken.

33. Blood Types Multiple Alleles

34. 34 1. GenotypesPhenotypes AAA AoA BBB BoBAB ooO Multiple Alleles

35. B A

36. See page 261 Mendelian Inheritance In Humans

37. See page 261 Mendelian Inheritance In Humans

38. 38 5. An individual ’ s phenotype often depends on conditions in the environment. 6. Some traits are affected by the temperature, sunlight or seasons. 7. In humans the environment influences height. Height is influenced by nutrition, an internal environment conditions.

39. Full coat color: CC CC ch Cc h Cc Chinchilla coat color: c ch c ch c h c ch c Himalayan coat color: c h c h c **temp Sensitive! Albino coat color: cc Multiple Alleles

40. 40 B. Some traits are caused by mutations

41. Sickle Cell Anemia ** NN is Not afflicted; Nn is a carrier; nn is afflicted **Sickle cell anemia is caused by an abnormal type of hemoglobin and cells become sickle shaped when oxygen is low **Sickle cells clot give rise to recurrent painful episodes called a “sickle cell pain crisis” ** “n” makes a person immune to malaria

42. Results in the absence of an enzyme that normally breaks down a lipid (fat) produced and stored in nervous tissues and brain

43. A child with Tay-Sachs Syndrome are mentally challenged

44. Phenylketonuria (PKU)  lacks an enzyme that converts one amino acid, phenylalanine, to a different amino acid, tyrosine. * Results in severe damage to the central nervous system. When detected in infants, dietary adjustments (about 1 in 15k babies born with it)

45. Phenylketonurics: Contains Phenylalanine

46. Genetic Methemoglobinemia *Although oxygen-poor blood is NOT blue, but appears bluish because of the distortion of skin “Blue People” who have too much methhemoglobin in their blood and oxygen cannot bind due to an enzyme deficiency **The Fugates of Hazard, Kentucky. Mom was a carrier while Dad had the disease Picture taken in the 1950’s

48. It results in a breakdown of certain areas of the brain. ~ Causes dementia due to progressive deterioration of the brain, increase in involuntary movements, eventually bedridden

49. Achondroplasia - type of dwarfism. AA genotypes are lethal and result in spontaneous abortion, Aa have dwarfism. 99% of Americans are aa

50. Polydactyl (extra fingers and/or toes): PP or Pp = extra digits. 98% of all people in the world are homozygous recessive (pp).

51. Progeria (very premature aging): * Most die before age 13 Spontaneous mutation of one gene creates a dominant mutation that rapidly accelerates aging.

52. 52 5. There is genetic testing to detect any bad genes. 6. Gene technology may soon by replacing defected genes with copies of healthy ones this is called gene therapy.