Genetics II Modes of Complex Inheritances and Pedigrees Nancy Dow Jill Hansen Tammy Stundon February 23, 2013

1. Biology Partnership (A Teacher Quality Grant) Genetics II Modes of Complex Inheritances and Pedigrees Nancy Dow Jill Hansen Tammy Stundon February 23, 2013

2. Pre-test Q and A board Was Mendel wrong? Why aren’t humans as simple as ‘tall’ or ‘short’? Why are most colorblind people males?

3. BENCHMARK SC.912.L.16.2* Discuss observed inheritance patterns caused by various modes of inheritance, including dominant & recessive which are simple inheritance & codominant, sex-linked, polygenic, and multiple alleles (complex inheritance). (HIGH) Florida Next Generation Sunshine State Standards

4. Florida Next Generation Sunshine State Standards Benchmark Clarifications Students will identify, analyze, and/or predict inheritance patterns caused by various modes of inheritance. Content Limits Items referring to general dominant and recessive traits may address but will not assess the P and F1 generations. Items addressing dihybrid crosses or patterns that include codominance, incomplete dominance, multiple alleles, sex- linkage, or polygenic inheritance may assess the P and F1 generations

5. Florida Next Generation Sunshine State Standards • Stimulus Attributes • Inheritance outcomes may be expressed in percent, ratios, or fractions. • Scenarios may refer to codominance or incomplete dominance but not both codominance and incomplete dominance. • Punnett squares may be used to predict outcomes of a cross. • Response Attribute • Options may include codominance or incomplete dominance but not both.

6. Mendel’s Results

7. Ways to inherit traits • Simple inheritance – the present of a dominant or two recessive alleles will express the trait • Dominant simple • Recessive simple • Sex-linked (x-linked) – where the 23rd chromosome work on different rules • Complex inheritance – the most common • Multiple Allele – • Co-dominance – • Polygenetic inheritance • Incomplete dominance

8. Simple inheritance (single gene) • Capital letter = Dominant trait • When just one dominant gene is present, the • trait will be shown • Two dominant alleles does not enhance the trait • For a recessive trait to be expressed both parents • MUST pass on the recessive allele for this trait to be present • Which genotype would be the carrier for the recessive trait? 1. Dominant Inheritance – Rr or RR Traits include widow’s peak, hitchhiker’s thumb, etc. .

9. EXAMPLES OF SINGLE-GENE TRAITS Widow’s peak is Dominant Straight hairline is recessive Hitchhiker’s is recessive Regular thumb is Dominant Six digits (D) Not able to roll the tongue is recessive Tongue rolling is Dominant

10. EXAMPLES OFSINGLE-GENETRAITS Cleft chin = r Non-cleft chin =D Attached earlobes = r Unattached earlobes = D Autosomal Simple Inheritance lab

11. Simple Dominant Inheritance Disease Huntington’s Disease • Chromosome #4; gene makes the brain cells to basically commit suicide • neurological spasms, mental problems, motor function problems • no treatment • CAG is repeated too many times; the number of repeats predicts the age of onset; 40 reps = late middle age

12. Carriers • Only the genotype Ff is considered to be a ‘carrier’ • If (F) = freckles, what is this person’s phenotype? • What type of simple inheritance are they expressing? • Effect if this was a disorder and not a trait? • Why wouldn’t the other simple inheritance genotype be considered as a carrier?

13. Simple inheritance (single gene) 2. Recessive Inheritance – rr • Disorders – Tay-sachs – Jewish, C#15 Cystic Fibrosis – Caucasians, C#7 PKU – C#12, metabolic disorder • Why certain disorders have appeared?....... • Lack of genetic variation ? Adaptation?

14. A SINGLE BAD GENE WHICH WILL NOT PRODUCE THE ENZYME TO CONVERT PHENYLALANINE TO TYROSINE (BOTH AMINO ACIDS). THIS CAUSES A CONDITION CALLED “PKU”. THIS CAN CAUSE A BUILD- UP OF PHENYLALANINE IN THE BRAIN WHICH CAN CAUSE MENTAL RETARDATION---CAN BE TREATED WITH DIET AVOIDING THIS AMINO ACID.

15. Higher order thinking questions! • They have to know what type of inheritance the disorder is in order to answer the question (by either doing a Punnett square or pedigree.) • Many test bank questions will indicate the inheritance of a trait; Freckles are dominant. Why cover disorders?

16. Human Autosomal Trait Lab Refer to the slides with the simple inheritance traits! …… ……

17. Non-Mendelian Genetics • Mendelian genetics describes inheritance patterns based on complete dominance or recessiveness. • There are other types of inheritance that Mendel never considered: • Incomplete Inheritance • Codominance • Multiple Alleles • Polygenic Traits • Sex-linked

18. Non-Mendelian Genetics The relationship between genotype and phenotype is rarely simple

19. Non-Mendelian Genetics • Many researchers have encountered exceptions to Mendelian Principles – sowas he wrong? • Majority of heritable characters not as simple as peas • Phenotypes affected by: many alleles or many genes, environmental factors, sex chromosomes, etc.

20. Phenotype can depend on interactions of alleles. In incomplete dominance, neither allele is completely dominant nor completely recessive. Heterozygous phenotype is intermediate between the two homozygous phenotypes Homozygous parental phenotypes not seen in F1 offspring

21. Incomplete Dominance If this was blended inheritance – pink • pink would only make what? If you cross a RED flower with a WHITE flower, you will get a PINK flower. NOTICE: the RED genotype is RR the WHITE genotype is WW the PINK genotype is RW INcompleteisINbetween

22. Let’s Practice! B B What percent is black? White? Gray? BW BW Black: 0% White: 0% Gray: 100% W BW BW W Cross a BLACK chicken (BB) with a WHITE chicken (WW). These alleles show INCOMPLETE DOMINANCE

23. Let’s Practice! B B What is the genotype and phenotype of the F1 generation? Genotype: BW Phenotype: Gray BW BW W BW BW W Cross a BLACK chicken (BB) with a WHITE chicken (WW). These alleles show INCOMPLETE DOMINANCE

24. Let’s Practice! B W Genotype: 1 BB 1 WW 2 BW Phenotype: 1 Black 1 White 2 Gray What is the genotype and phenotype of the F2 generation? BB BW B BW WW W PTC Testers What would the cross look like if you crossed two GREY chickens (BW). These alleles show INCOMPLETE DOMINANCE.

25. CoDominance Both traits are dominant, and show up in the phenotype together. Co means “together” Black Cow X White Cow = SpottedCow (BB) (WW) (BW)

26. CoDominance • Both alleles are expressed in the heterozygous condition • Both alleles contribute to the phenotype. • For Example: In chickens, the allele for black feathers is co-dominant with the allele for white feathers. These chickens will have BOTHblack and white feathers. COdominant alleles COllaborate together

27. Let’s Practice! B B How many chickens in the F1 generation are completely black? White? Black and white? BW BW W Black: 0% White: 0% Both: 100% BW BW W Cross a Black chicken (BB) with a White chicken (WW). These alleles show CO-DOMINANCE.

28. Let’s Practice! B B What is the genotype and phenotype of the F1 generation? Genotype: BW Phenotype: Black and white or checkered. BW BW W BW BW W Cross a Black chicken (BB) with a White chicken (WW). These alleles show CO-DOMINANCE.

29. Let’s Practice! B W Genotype: 1 BB 1 WW 2 BW Phenotype: 1 Black 1 White 2 Checkered List all possible genotypes and phenotypes of the F2 generation. BW BB B WW BW W Cross two Black and White (checkered) chickens (BW). These alleles show CO-DOMINANCE

30. Blood type displays both co-dominance and complete dominance Blood types are different based on the presence or absence of certain antigens on the red blood cells (RBCs) The presence of a antigen (I) is dominant to the absence of an antigen (i). There are two types of antigens that may exist on the surface of RBCs called A (IA) and B (IB). Cell surface antigens A and B are codominant, which means they could also show up at the same time on an RBC.

31. Matching compatible blood groups is critical for blood transfusions because a person produces antibodies against foreign blood factors. Blood type displays both co-dominance and complete dominance

32. Blood type also demonstrates inheritance through multiple alleles • Multiple alleles: When more than 2 varieties exist in a trait. In this case, blood can be A/B/O

33. Multiple Alleles—ABO Blood Groups At any one time, a parent can only have TWO alleles for blood Possible alleles from female Possible alleles from male Blood Types A AB B O

34. The Genetics of Blood Lab

35. Polygenic Inheritance • The inheritance pattern is controlled by two or more genes (each with two alleles) At the present, three gene pairs controlling human eye color are known (two on chromosome 15 and one on pair 19). Order of dominance: brown/amber > green/hazel > gray/blue.

36. Polygenic Inheritance Creates a ‘bell curve’ distribution • Two or more genes work together to create a single phenotype • Example: Height is controlled by anywhere from 7 – 20 different genes (and the environment!) Wilt Chamberlin stood 7’1” tall, neither of his parents was over 5’9”

37. Polygenic Inheritance • Skin color is determined by (at least) 3 genes. Imagine that each gene has two alleles, one light and one dark, that demonstrate incomplete dominance. • An AABBCC individual is dark and aabbcc is light. Polygenic Inheritance Activity

38. Sex Linked Traits • When a trait is carried on the X or Y chromosomes, it is called a sex-linked trait • These not only carry the genes that determine male and female traits but also those for some other characteristics as well • Don’t confuse this with linked genes = when 2 genes are on the same chromosome

39. Sex Linked Traits Red – Green Color Blindness • Gene that controls this is on the X chromosome • Who is more likely to be color blind– men or women? • Men: only 1 X chromosome • If they have the recessive allele they don’t have another X to make up for it.

40. Sex Linked Traits  If there is not a normal gene present to offset the defective, recessive gene, the disorder will be present.

41. Gene linkage was explained through fruit flies Attention to detail, accurate lab records were critical Different than sex influenced genes

42. Females can carry sex-linked disorders. Males (XY) express all of their sex linked genes. Expression of the disorder depends on which parent carries the allele and the sex of the child. Y X

44. Question: If a normal male (do those even exist?) has a child with a woman who carries the blindness allele, what are the chances that their children will be colorblind? Will any children be carriers of the trait? X Y X XX XY Xc XXc XcY

45. Pedigrees • A diagram that traces the inheritance of a particular trait through several generations.

46. Pedigrees • Chart showing the genetic connections among individuals in a family • Especially useful in following recessive alleles that are not visible in the heterozygote

47. Royal Pedigrees Royal Pedigrees I’m my own grandpa

48. The environment interacts with genotype. • Phenotype is a combination of genotype and environment. • Height is a example of a phenotype strongly affected by the environment. • diet/exercise • sunlight/water (if you’re a plant) Nature vs. Nurture Virtually all human diseases have some genetic component

49. 15 minutes!!

50. Eye Color and Polygenic Inheritance/Pedigree Lab