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Solving Genetics Problems

Honors Biology Unit 5 Powerpoint #2 / Chapter 11. Solving Genetics Problems. Solving Genetics Problems. Phenotype: physical appearance Example: Tall, Short, Blonde, Red, Brown Eyes Genotype: genes in the DNA (alleles) Example: TT bb Rr Bb.

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Solving Genetics Problems

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  1. Honors Biology Unit 5 Powerpoint #2 / Chapter 11 Solving Genetics Problems

  2. Solving Genetics Problems Phenotype: physical appearance Example: Tall, Short, Blonde, Red, Brown Eyes Genotype: genes in the DNA (alleles) Example: TT bb Rr Bb

  3. 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 T t

  4. Solving Genetics Problems • Dominant: An allele that causes its phenotype if at least 1 is present Examples: TT, Tt (Tall) • Recessive: An allele that causes a phenotype only when there are 2 alleles Example: tt (short)

  5. Solving Genetics Problems Homozygous: organism with 2 identical alleles for a trait (TT or tt) Heterozygous: organism with 2 different alleles for a trait (Tt)

  6. Solving Genetics Problems Homozygous dominant: has 2 dominant alleles (TT) Homozygous recessive: has 2 recessive alleles (tt)

  7. A B C D E F G H Plant A: a. Phenotype: b. Genotype: Tall TT

  8. A B C D E F G H Plant B: a. Phenotype: b. Genotype: short tt

  9. A B C D E F G H Plant C: a. Phenotype: b. Genotype: Tall Tt

  10. Solving Genetics Problems Genetics Problems Goal: to predict the traits of offspring

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

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

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

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

  15. 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. • Assign letters: tall = T short = t • Parents’ genotypes True breeding tall: TT True breeding short = tt

  16. Solving Genetics Problems 3. Draw Punnett Square

  17. Solving Genetics Problems 3. Draw Punnett Square t t T T

  18. Solving Genetics Problems 3. Draw Punnett Square t t T T

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

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

  21. 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. black = ____ white = ____

  22. 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.

  23. 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: ___

  24. 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: ___

  25. 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: ___

  26. 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

  27. Solving Genetic Problems 3. Draw Punnett Square B b b b

  28. 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 Bb b b

  29. 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

  30. 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. • 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 Attached

  31. 1) A mother is homozygous dominant for ear type and a father is heterozygous: • Draw a punnett square: e E E EE Ee Ee EE E

  32. 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 E Ee EE 50% Ee EE E 50% 0%

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

  34. 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

  35. 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 Yes! r Rr rr rr Rr r

  36. 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

  37. Co and IncompleteDominance

  38. definitions • Co-dominance: Both alleles are dominant and contribute to the phenotype of a heterozygous individual • Incomplete Dominance: One allele is NOT completely dominant over the other

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

  40. Co-dominance

  41. Fill in the Punnett Square Genotypes Phenotypes R R RW W RW RW RW W

  42. 2. R= Red Fur W= White Fur • What do you think a RW 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 RW: ______________ Red and White spots RR Red Fur WW White Fur 100%

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

  44. Phenotypes PP GG GP

  45. Incomplete Dominance • The heterozygous (Rr) Does not look like the Homozygous recessive (rr) or the homozygous dominant (RR).

  46. Incomplete Dominance • In flowers there is a gene for Red (R) which has incomplete dominance to the recessive color white (r). The heterozygote plant produced by a white and red flower is pink RR rrRr

  47. Solve the following crosses: Incomplete Dominance

  48. B= Black (Incomplete Dominance)b = Yellow (Recessive) • What is the genotype for a dog that is Black : ______ • What is the genotype for a dog that is Yellow :_____ • What is the genotype for a dog that is Brown: ______ • Show a cross between a Brown dog and a yellow dog. BB bb Bb

  49. Fill in the Punnett Square Genotypes Phenotypes B b bb b Bb Bb bb b

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