2. SOLVING GENETICS PROBLEMS Biology Unit 6 Powerpoint #2 / Chapter 11 Mr. Velekei

3. Vocabulary 9. Phenotype 10. Genotype 11. Dominant 12. Recessive 13. Homozygous 14. Heterozygous

4. Unit 6: Genetics

15. SOLVING GENETICS PROBLEMS Honors Biology Unit 5 Powerpoint #1 / Chapter 11

16. Traits What are some of your traits? Where did they come from? Do you look like one of your parents, a combination, or neither? Do certain traits “run” in your family? Or pop up after skipping a generation What traits are common in our class? why do you think that is?

17. Terminology Gene: segment of DNA that determines a trait (protein) Alleles: different forms of a gene (ex: Height: tall allele, or short allele)

18. Chromosome # 12

19. Genotype vs. phenotype Difference between how an organism “looks” & its genetics phenotype description of an organism’s trait the “physical” genotype description of an organism’s genetic makeup Explain Mendel’s results using …dominant & recessive …phenotype & genotype F1F1 P X purplewhite all purple

20. Notation A capital letter represents the dominant allele. A lower case letter represents the recessive allele. Example: Pea plant height – Tall: T Short: t

21. Dominant: An allele that causes its phenotype in a heterozygous genotype. Examples: TT, Tt (Tall) Recessive: An allele that causes a phenotype only seen in a homozygous genotype. Example: tt (short) Remember…

22. Allele: A variety of a gene A gene for hair color could have the allele: _______ for Brown hair or _______ for Blonde hair A gene for flower color could have allele: ______for blue flower or ________ for red flower A gene for height could have the alleles: _______ for tall or _______ for short B b B b Tt

23. Making crosses Can represent alleles as letters flower color alleles  P or p true-breeding purple-flower peas  PP true-breeding white-flower peas  pp PP x pp PpPp F1F1 P X purplewhite all purple

24. Solving Genetics Problems Homo zygous: organism with two identical alleles for a trait Hetero zygous: organism with two different alleles for a trait

25. Homozygous dominant: organism with two dominant alleles Homozygous recessive: organism with two recessive alleles Solving Genetics Problems

26. A B C D E F G H Plant A: a. Phenotype: b. Genotype:

27. A B C D E F G H Plant B: a. Phenotype: b. Genotype:

28. A B C D E F G H Plant C: a. Phenotype: b. Genotype:

29. F 2 generation 3:1 75% purple-flower peas 25% white-flower peas ???? Looking closer at Mendel’s work P X true-breeding purple-flower peas true-breeding white-flower peas PPpp 100% F 1 generation (hybrids) 100% purple-flower peas PpPpPpPpPpPpPpPp phenotype genotype self-pollinate

30. Hybrid: offspring of crosses between parents with different traits. Example: Cross pollinate a true-breeding purple flower and a true breeding white flower. Seedlings=hybrid (even though they are purple) X =

31. Hybrid Cars Gas + Electric

33. Solving Genetics Problems We need a method to predict the traits of the offspring, and we have it, its called the Punnett Square!

34. Solving Genetics Problems Genetics Problems Goal: to predict the traits of offspring 1. Identify trait(s) and assign a letter to each (capital letter for dominant, lower case letter for recessive)

35. Solving Genetics Problems Genetics Problems Goal: to predict the traits of offspring 1. Identify trait(s) and assign a letter to each (capital letter for dominant, lower case letter for recessive) 2. Determine parents’ genotypes

36. Solving Genetics Problems Genetics Problems Goal: to predict the traits of offspring 1. Identify trait(s) and assign a letter to each (capital letter for dominant, lower case letter for recessive) 2. Determine parents’ genotypes 3. Draw Punnett square and fill in

37. Solving Genetics Problems Genetics Problems Goal: to predict the traits of offspring 1. Identify trait(s) and assign a letter to each (capital letter for dominant, lower case letter for recessive) 2. Determine parents’ genotypes 3. Draw Punnett square and fill in 4. Determine the probabilities for offspring of each genotype and phenotype

38. Solving Genetics Problems Example: In pea plants, the gene for tall height is dominant to the gene for short height. A short pea plant is cross pollinated with a true breeding tall pea plant. 1. Assign letters: tall = Tshort = t 2. Parents’ genotypes True breeding tall: TT True breeding short = tt

39. Solving Genetics Problems 3. Draw Punnett Square

40. Solving Genetics Problems 3. Draw Punnett Square t t TTTT

41. Solving Genetics Problems 3. Draw Punnett Square Tt t t TTTT

42. Solving Genetics Problems 4. Calculate probabilities TT = _____ Tt = ________ tt = _________ Tall = _________ Short = _________ Tt t t TTTT

43. Solving Genetics Problems 4. Calculate probabilities 10) TT = 0/4 Tt = 4/4 tt = 0/4 11) Tall = 4/4 Short = 0/4 Tt t t TTTT

44. Punnett squares Pp x Pp Pp male / sperm P p female / eggs PP 75% 25% 3:1 25% 50% 25% 1:2:1 % genotype % phenotype PPPpPp PpPppp PpPp PpPp F 1 generation (hybrids) Aaaaah, phenotype & genotype can have different ratios

45. Genotypes Homozygous = same alleles = PP, pp Heterozygous = different alleles = Pp homozygous dominant homozygous recessive heterozygous

46. Phenotype vs. genotype 2 organisms can have the same phenotype but have different genotypes homozygous dominant PPpurplePpPp heterozygous purple How do you determine the genotype of an individual with with a dominant phenotype? Can’t tell by lookin’ at ya!

47. Test cross Breed the dominant phenotype — the unknown genotype — with a homozygous recessive (pp) to determine the identity of the unknown allele pp is it PP or Pp? x

48. PPpp How does a Test cross work? pp P P pp P p PpPppp xx PpPp PpPpPpPp PpPp 100% purple PpPp pp PpPp 50% purple:50% white or 1:1 pp Am I this? Or am I this?

49. Mendel’s 1 st law of heredity Law of segregation during meiosis, alleles segregate homologous chromosomes separate each allele for a trait is packaged into a separate gamete PP P P pp p p PpPp P p

50. Segregation of alleles and fertilization as chance events

51. Identify trait(s) and assign a letter to each (capital letter for dominant, lower case letter for recessive. Examples: In guinea pigs, the gene for black fur is dominant to the gene for white fur.

52. Determine parents’ genotypes. Example: In guinea pigs, the gene for black fur is dominant to the gene for white fur. A white guinea pig and a hybrid black guinea pig produce 20 offspring. Find the probability of offspring genotypes and phenotypes. 1. Black: ___White: ___ 2. White guinea pig: ___ Hybrid black guinea pig: ___

53. Determine parents’ genotypes. Example: In guinea pigs, the gene for black fur is dominant to the gene for white fur. A white guinea pig and a hybrid black guinea pig produce 20 offspring. Find the probability of offspring genotypes and phenotypes. 1. Black: B White: b 2. White guinea pig: ___ Hybrid black guinea pig: ___

54. Determine parents’ genotypes. Example: In guinea pigs, the gene for black fur is dominant to the gene for white fur. A white guinea pig and a hybrid black guinea pig produce 20 offspring. Find the probability of offspring genotypes and phenotypes 1. Black: B White: b 2. White guinea pig: bb Hybrid black guinea pig: ___

55. Determine parents’ genotypes. Example: In guinea pigs, the gene for black fur is dominant to the gene for white fur. A white guinea pig and a hybrid black guinea pig produce 20 offspring. Find the probability of offspring genotypes and phenotypes. 1. Black: B White: b 2. White guinea pig: bb Hybrid black guinea pig: Bb

56. Solving Genetics Problems 4. Calculate probabilities BB = 0/4 Bb = 2/4 (50%) bb = 2/4 (50%) How many of the babies will Probably be Black = 10 How many of the babies will Probably be White = 10 Bbbb Bbbb Bb bbbb

57. Tongue Rolling: Dominant If a mother can roll her tongue and a father can not. What do we know about their genes?

58. Tongue Rolling: Dominant If a mother can roll her tongue and a father can not. What do we know about their genes? Mother: _______ Father: _______ RR or Rr rr only

59. 2) B. If you know that they have 2 children, one that can roll and one that can not. Will that give you more info about the parent’s genotypes? c. Draw a punnett square: r r r R RrRr RrRr r r Yes!

60. Tongue Rolling: Dominant d. Which people in the family would be considered hybrids? e. Are their any genotypes that this mother and father can not produce in their offspring? Why or why not? Mom and the child that can roll their tongue Yes, they can not produce a Homozygous Dominant (RR) child because the father only has recessive genes (r) to pass on

61. Humans can have unattached earlobes (picture A) or attached earlobes (picture B). Attached earlobes are dominant. Use the letter ‘E’ to complete the following questions. Ear Lobes

62. Humans can have unattached earlobes (picture A) or attached earlobes (picture B). Attached earlobes are dominant. Use the letter ‘E’ to complete the following questions. 1) A mother is homozygous dominant for ear type and a father is heterozygous: a) What is the mother’s genotype? ______ Father’s genotype? ____ b) What are their phenotypes? Mother: ___________ Father: _________ EE Ee Attached

63. 1) A mother is homozygous dominant for ear type and a father is heterozygous: Draw a punnett square: E E e E E E EeEe EeEe

64. 1) A mother is homozygous dominant for ear type and a father is heterozygous: d: What are the chances they will have children that are: Homozygous Dominant: ____ Heterozygous: ____ Homozygous Recessive: ____ E E eE E E EeEe EeEe 50% 0%

65. DIHYBRID (2 FACTOR) CROSSES + INCOMPLETE AND CO- DOMINANCE

66. Monohybrid cross Some of Mendel’s experiments followed the inheritance of single characters flower color seed color monohybrid crosses

67. Dihybrid (2 factor) cross Other of Mendel’s experiments followed the inheritance of 2 different characters seed color and seed shape dihybrid (2 factor) crosses Mendel was working out many of the genetic rules!

68. Dihybrid cross true-breeding yellow, round peas true-breeding green, wrinkled peas x YYRRyyrr P 100% F 1 generation (hybrids) yellow, round peas Y = yellow R = round y = green r = wrinkled self-pollinate 9:3:3:1 9/16 yellow round peas 3/16 green round peas 3/16 yellow wrinkled peas 1/16 green wrinkled peas F 2 generation YyRr

69. What’s going on here? If genes are on different chromosomes… how do they assort in the gametes? together or independently? YyRr YRyr YyRr YryR YRyr Is it this?Or this? Which system explains the data?

70. 9/16 yellow round 3/16 green round 3/16 yellow wrinkled 1/16 green wrinkled Is this the way it works? YyRr YRyr YR yr x YyRr YryRYR yr YyRr YRyr or YYRRYyRr yyrr 

71. Dihybrid cross YyRr YRYryR yr YR Yr yR yr YYRR x YYRrYyRRYyRr YYRrYYrrYyRrYyrr YyRRYyRryyRRyyRr YyRrYyrryyRryyrr 9/16 yellow round 3/16 green round 3/16 yellow wrinkled 1/16 green wrinkled YyRr YryRYR yr YyRr YRyr or 

72. The laws of probability govern Mendelian inheritance Rule of Multiplication: probability that 2+ independent events will occur together in a specific combination  multiply probabilities of each event Ex. 1: probability of throwing 2 sixes 1/6 x 1/6 = 1/36 Ex. 2: probability of having 5 boys in a row ½ x ½ x ½ x ½ x ½ = 1/32

73. The laws of probability govern Mendelian inheritance Rule of Addition: Probability that 2+ mutually exclusive events will occur  add together individual probabilities Ex. 1: chances of throwing a die that will land on 4 or 5? 1/6 + 1/6 = 1/3

74. Mendel’s 2 nd law of heredity round wrinkled Law of independent assortment different loci (genes) separate into gametes independently non-homologous chromosomes align independently classes of gametes produced in equal amounts YR = Yr = yR = yr only true for genes on separate chromosomes or on same chromosome but so far apart that crossing over happens frequently yellow green :11:1:1 Yr yR YR yr YyRr

75. Review: Mendel’s laws of heredity Law of segregation monohybrid cross single trait each allele segregates into separate gametes established by Metaphase 1 Law of independent assortment dihybrid (or more) cross 2 or more traits genes on separate chromosomes assort into gametes independently EXCEPTION  linked genes

76. Beyond Mendel’s Laws of Inheritance

77. Vocabulary 15. Co-dominance 16. Incomplete dominance 17. Probability

78. Extending Mendelian genetics Mendel worked with a simple system peas are genetically simple most traits are controlled by a single gene each gene has only 2 alleles, 1 of which is completely dominant to the other The relationship between genotype & phenotype is rarely that simple

79. Incomplete dominance Heterozygote shows an intermediate, blended phenotype example: RR = red flowers rr = white flowers Rr = pink flowers make 50% less color RR  RR  WW  RW WWRW

80. Incomplete dominance true-breeding red flowers true-breeding white flowers X P 100% 100% pink flowers F 1 generation (hybrids) self-pollinate 25% white F 2 generation 25% red 1:2:1 50% pink It’s like flipping 2 pennies!

81. Fill in the Punnett Square B b B bBb Genotypes Phenotypes

82. What percentages will the F1 be: BB: _______% Bb: ________% bb: ________% Black:_________% White:_________% Hybrid: ________% 0 100 0 0 0

83. BbBb BbBb BBBb Bbbb BB: ________% Bb: ________% bb: ________% Black:_______%

84. BbBb BbBb BBBb Bbbb BB: 25% Bb: 50% bb: 25% Black: 25%

85. definitions Co-dominance: Both alleles are dominant and contribute to the phenotype of a heterozygous individual

86. Solve the following crosses: Co-Dominance 3. In Cows the trait for coat (fur) color is expressed by F R for Red fur and F W for white fur. The hybrid of the two is called a Roan color (F R F W ) a) Describe what you think the Roan cow’s fur will look like:

88. Co-dominance

89. 2. F R = Red Fur F W = White Fur What do you think a F R F W cow will look like: ____________________ If the mother cow is homozygous red for fur color. What is her genotype: _____ Phenotype?________________ If the dad is homozygous white for fur color. What is his genotype: _____ Phenotype?________________ What percentage of the offspring will be F R F W : ______________ Red and White spots FRFRFRFR Red Fur FWFWFWFW White Fur 100%

90. Fill in the Punnett Square FWFW FRFR FWFW FRFR FRFWFRFW FRFWFRFW FRFWFRFW FRFWFRFW Genotypes Phenotypes

91. Solve the following crosses: Co-Dominance In mushrooms there is a gene for Purple Spots (S P ) and a gene for Green spots (S G ). Cross a Homozygous purple with a Homozygous Green. a) What do you think their offspring will look like? Genotype? Phenotype? b) What will the genotype and phenotype percentages be in the F2 when you cross two from the F1 generation.

92. Phenotypes & Genotypes S P S P S G S G 100 % S P S G

93. b) F 1 x F 1 S P S G SPSGSPSG S P S P S P S G S P S G S G S G S P S P= 25% S P S G= 50% S G S G= 25% Green Spots = 25% G & P Spots = 50% Purple Spots = 25%

94. Pleiotropy Most genes are pleiotropic one gene affects more than one phenotypic character 1 gene affects more than 1 trait dwarfism (achondroplasia) gigantism (acromegaly)

95. Acromegaly: André the Giant

96. Epistasis B_C_ bbC_ _ _cc One gene completely masks another gene coat color in mice = 2 separate genes C,c: pigment (C) or no pigment (c) B,b: more pigment (black=B) or less (brown=b) cc = albino, no matter B allele 9:3:3:1 becomes 9:3:4

97. Polygenic inheritance Some phenotypes determined by additive effects of 2 or more genes on a single character phenotypes on a continuum human traits skin color height weight intelligence behaviors