Non-Mendelian Genetics:

1. Non-Mendelian Genetics:

2. 89. Pedigree 90. Sex-linked trait 91. Polygenic trait 92. Incomplete dominance 93. Codominance 94. Multiple alleles 95. mutation Vocabulary Terms… Read 171-180

3. Chromosomes and Human Genetics • Human Chromosomes • Types • Sex Chromosomes – 1 pair – carry the genes that determine male and female features (also some non-sex traits) • X and Y do not look alike but behave as a homologous pair at meiosis • XX = female, XY = male • Autosomes – non-sex chromosomes (22 pairs) – genes are unrelated to sex determination

4. B. Determining Sex… MOM X X X X X X X DAD X Y X Y Y

5. II. Gene Location • Linked – Linkage Groups – genes located so close together on a chromosome that the traits always seem to appear together Ex. Red hair and freckles Ex. Colorblindness and Hemophilia X X

6. Sex-linked Traits – genes on the sex chromosomes • Expression of certain genes often appears more in one sex than the other • Males require only one copy of a gene since they only have one X chromosome • See Royal Families of Europe Pedigree • Ex. Eye color in fruit flies, hemophilia, color-blindness

7. Colorblindness Tests

9. X-Linked/Sex Linkage – do not write • Genes present on the X chromosome exhibit unique patterns of inheritance due to the presence of only one X chromosome in males. • X-linked disorders show up rarely in females • X linked disorders show up in males whose mothers were carriers (heterozygotes)

10. Practice Sex-linked Problems…. • What will the result of mating between a normal (non-carrier) female and a hemophiliac male?

11. A female carrier who is heterozygous for the recessive, sex-linked trait causing red-green colorblindness, marries a normal male. What proportions of their MALE progeny will have red-green colorblindness?

12. Hemophilia is inherited as an X-linked recessive. A woman has a brother with this defect and a mother and father who are phenotypically normal. What is the probability that this woman will be a carrier if she herself is phenotypically normal?

13. Hemophilia is inherited as an X-linked recessive. • A man with Hemophilia has several children with a woman who has a normal phenotype and is NOT a carrier. What % of the children have hemophilia? What % are carriers?

14. C. Gene Interactions • Polygenetic trait – many genes influence a single trait (ex. Height, intelligence) • Pleiotropic effect – one gene having many effects (ex. Gene to make testosterone)

15. Pleiotropy ? • Expression of a single gene has multiple phenotypic effects • Marfan Syndrome – abnormal gene that makes fibrillin (important in connective tissues)

16. III. Genetic Analysis • Karyotype – visualized chromosomes stained, squashed, and photographed at metaphase - They are characteristic of the species or individual

17. B. Pedigree – chart showing family relationships (see worksheet)

18. Pedigree Analysis • Method of tracking a trait through generations within a family. • Good method of tracking sex-linked traits as well as autosomal traits.

20. Sex-Linked Pedigree • Shows gender bias with males exhibiting the trait more often than females

22. Autosomal Dominant Pedigree • Autosomal dominant traits do not skip a generation • Autosomal dominant traits do not show gender bias

23. Autosomal Recessive Pedigree • Autosomal recessive traits skip a generation • Autosomal recessive traits do not show gender bias

24. IV. Non-Mendelian Genetics • Incomplete Dominance – blended inheritance • Neither form of the gene is able to mask the other • Ex. Snap dragon petal color • R1R1 – RED • R1R2 – PINK • R2R2 - WHITE

25. Incomplete Dominance • Neither allele is dominant • Heterozygotes are a blend of homozygous phenotypes = no distinct expression of either allele

26. Try these • In a plant species, if the B1allele (blue flowers) and the B2 allele (white flowers) are incompletely dominant (B1 B2is light blue), what offspring ratio is expected in a cross between a blue-flowered plant and a white-flowered plant?

27. What would be the phenotypic ratio of the flowers produced by a cross between two light blue flowers?

28. 2. Codominance • No dominance and both alleles are completely expressed • Ex. Cat color • C1C1 – Tan • C1C2 – Tabby (black and tan spotted) • C2C2 - Black

29. Try These • Cattle can be red (RR = all red hairs), white (WW = all white hairs), or roan (RW = red & white hairs together. • Predict the phenotypic ratios of offspring when a homozygous white cow is crossed with a roan bull.

30. What should the genotypes & phenotypes for parent cattle be if a farmer wanted only cattle with red fur?

31. A cross between a black cat & a tan cat produces a tabby pattern (black & tan fur together). • What pattern of inheritance does this illustrate? • What percent of kittens would have tan fur if a tabby cat is crossed with a black cat?

32. 3. Multiple Alleles • More than 2 alleles for one trait • Ex. Eye color, hair color, blood type, guinea pig fur color • ABO blood groups • Each individual is A, B, AB, or O phenotype • Phenotype controlled by marker on RBC • IA and IB alleles are dominant to the i allele • IA and IB alleles are codominant to each other

33. Blood Type: A B AB O Genotype IAIA , IAi IBIB , IBi IAIB ii Blood Types

35. Try These • If a male is homozygous for blood type B and a female is heterozygous for blood type A, what are the possible blood types in the offspring?

36. Is it possible for a child with Type O blood to be born to a mother who is type AB? Why or why not?

37. A child is type AB. His biological mother is also type AB. What are the possible phenotypes of his biological father?

38. Human hair color follows a similar pattern: Alleles: HBn = brown HBd = blonde hR = red hbk = black HBnHBn = dark brown HBnHBd = sandy brown HBnhR = auburn HBnhbk = dark brown HBdHBd = blonde HBdhR = strawberry blonde HBdhbk = blonde hRhR = red hRhbk = red hbkhbk = black Recessive can be common! Dominant does NOT mean frequent!

39. V. Genetic Conditions • Genetic Abnormality – rare condition with little or no ill effects - Ex. Six fingers, albino, colorblindness

40. 2. Genetic Disorders • Inherited condition that results in a medical problem - Ex. Huntington’s Disease, Sickle Cell Anemia, Hemophilia, Muscular Dystrophy

41. 3. Genetic Disease • A genetic condition that makes the individual susceptible to infection (bacterial or viral) - Ex. Cystic fibrosis, Down syndrome, SCID (severe combined immunodeficiency disease = bubble boy)

42. VI. Mutations • Definition – any change in the DNA • Possible outcomes: good, bad, or no effect • Location: • Somatic Cell (body cell) – can lead to cancer • Sex Cell – reproductive organ effecting gametes

43. Observed vs. Expected Ratios • Observed Ratio – what you actually get from two organisms having offspring – all girls • Expected Ratio – based on your punnett square results – what you would expect to get – half girls and half boys • Example – using dice

44. Human Genetics Test Topics • Sex-linked Traits • Incomplete Dominance/ Codominance • Multiple Alleles (blood typing problems) • Genetic Conditions • Sex Chromosomes vs. Autosomes • Pedigrees/Karyotypes • Observed vs. Expected Ratios • LOTS OF GENETICS PROBLEMS – SHOW WORK!!!

45. Human Genetics Test Review Questions: My daughter is type A, my grandson is type B. What are the blood type(s) that the father would have to be in order for my grandson to be type B?

46. Red-green color blindness is X-linked in humans. If a male is red-green color blind, and both parents have normal color vision, which of the male's grandparents is most likely to be red-green color blind? • A. maternal grandmother • B. maternal grandfather • C. paternal grandmother • D. paternal grandfather • E. either grandfather is equally likely

47. Suppose a child is of blood type A and the mother is of type 0. What type or types may the father belong to?

48. Suppose a father and mother claim they have been given the wrong baby at the hospital. Both parents are blood type A. The baby they have been given is blood type O. What evidence bearing on this case does this fact have?

49. Hemophilia is a sex-linked recessive trait. Cross a hemophiliac female with a normal male. Of all their offspring, what is the probability they will produce a hemophiliac daughter? (H = normal blood, h = hemophilia)

50. A man with Type A blood marries a woman with Type B blood. They have a type O child. What is the probability of their 15th child having type O blood?