2. GENETICS - WHO ARE THE PARENTS? AB

4. Genetics Vocabulary Genetics—the study of heredity; studying the transfer of traits from one generation to the next Trait—a physical characteristic that is inherited; examples of traits are eye color, hair color, pea shape, tail length, etc.

5. Genetics Vocabulary Gene—a specific region of DNA on a chromosome that codes for a particular trait. Heredity— the passing of traits from parent to offspring.

6. Genetics Vocabulary! Alleles—any of the possible forms of the same gene. Example: the gene for eye color has alleles for brown eyes, blue, green, black, etc. Dominant allele—an allele that will always be seen when two different alleles are present. Written as a capital letter, like “T” Recessive allele—an allele that will be hidden by a dominant allele; it is only expressed if two copies are present in an organism’s genotype. Written as a lower case letter, like “t”

7. Genotype (gene type) — a list of the alleles that an organism has for a particular trait Ex) AA, Aa, aa, Bb, AaBb, AAbb Phenotype (physical type) — the physical description of the traits an organism has Ex) “tall, short, brown, wrinkled seeds, smooth, straight stem, red” Genetics Vocabulary!

8. RHYME TIME! “Phen is SEEN!” You see the phenotype. It was determined by the genotype (letters).

9. Homozygous (homo=same)- having two of the same alleles for a trait. ◦ Ex: tt, bb, AA, RR, mm ◦ Also known as a “purebred” Heterozygous (hetero= different)- having two different alleles for a trait. ◦ Ex: Tt, Bb, Aa, Rr, Mm ◦ Also known as a “hybrid” Genetics Vocabulary!

10. 9 Genotype, Phenotype, homo/heterozygous Genotype of alleles: R = red tulip r = yellow tulip All genes occur in pairs, so 2 alleles affect this trait (characteristic) Possible combinations are: GenotypesPhenotypes RR RrRr rr RED YELLOW

11. IMPORTANT VOCABULARY! Monohybrid Cross – cross (breeding) involving only one trait e.g. flower color Dihybrid Cross – cross involving two traits e.g. flower color and plant height

12. Gregor Mendel- The Father of Genetics! Lived from 1822-1884 An Austrian Monk and Biologist Taught High School Worked with pea plants in the monastery garden.

13. 12 Where Gregor Mendel experimented on his pea plants at the monastery.

14.  Called the “Father of Genetics“  Mendel tested at least 28,000 pea plants  Mendel looked at 8 traits of pea plants  He found that the plants' offspring showed traits of the parents Gregor Mendel Pea Plant Traits

15. 14  Mendel stated that physical traits are inherited as “particles”  Mendel did not know that the “particles” were actually Chromosomes (coiled up DNA) Inheriting “Particles”

16. MENDEL’S experiments Crossed pea plants to look at some different traits: 1. Purple or white flowers 2. Tall or short plants 3. Wrinkled or round peas 4. Yellow or green peas

17. 16 Generation Names (P) generation = parental generation in a breeding experiment (P) generation = parental generation in a breeding experiment (F 1 ) generation = the first-generation offspring (F comes from a Latin word for “son”) (F 1 ) generation = the first-generation offspring (F comes from a Latin word for “son”) (F 2 ) generation = the second-generation offspring. (F 2 ) generation = the second-generation offspring.

18. 17 Following the Generations Cross 2 Pure Plants Results in all Hybrids Cross 2 Hybrids get 3 Tall & 1 Short TT x tt Tt TT, Tt, tt

19. Punnett Square A grid for determining possible genotypes of offspring. Possible alleles come from gametes formed during meiosis. Monohybrid Cross = One trait

20. Punnett Square Steps: 1. READ and UNDERLINE each problem 2. Make a KEY!!! 3. Make your cross mom X dad 4. Fill in your Punnett square 5. Determine probability

21. Lets try this together… Brown eyes are dominant to blue eyes. What are the chances of getting a blue eyed child if we cross 2 heterozygous brown eyed parents? 2. Key: 3. ______X______ Genotypes: _____________________ Genotypic Ratio: _________________ % Genotypic Ratio: Phenotypes: _____________________ Phenotypic Ratio: _________________ % Phenotypic Ratio:

22. And Again… Grey fur is dominant to white fur in mice. Cross a heterozygous grey dad with a white mom. What are the possible colors of offspring? Key: ____X____ Genotypes: _____________________ Genotypic Ratio: _________________ % Genotypic Ratio: Phenotypes: _____________________ Phenotypic Ratio: _________________ % Phenotypic Ratio:

23. Your Turn…remember to do all your steps! Purple flowers are dominant to white flowers. What color offspring we get if we crossed a homozygous purple flower with a white flower? Genotypes: _____________________ Genotypic Ratio: _________________ % Genotypic Ratio: Phenotypes: _____________________ Phenotypic Ratio: _________________ % Phenotypic Ratio:

24. 23 Trait: Seed Shape Trait: Seed Shape Alleles: R – Roundr – Wrinkled Alleles: R – Roundr – Wrinkled Cross: Round seeds x Wrinkled seeds Cross: Round seeds x Wrinkled seeds RR x rr RR x rr P 1 Monohybrid Cross R R rr Rr Genotype:Rr Genotype: Rr PhenotypeRound Phenotype: Round Genotypic Ratio:All alike Genotypic Ratio: All alike Phenotypic Ratio: All alike copyright cmassengale

25. 24 Trait: Seed Shape Trait: Seed Shape Alleles: R – Roundr – Wrinkled Alleles: R – Roundr – Wrinkled Cross: Round seeds x Round seeds Cross: Round seeds x Round seeds Rr x Rr Rr x Rr F 1 Monohybrid Cross R r rR RR rrRr Genotype:RR, Rr, rr Genotype: RR, Rr, rr PhenotypeRound & wrinkled Phenotype: Round & wrinkled Geno Ratio:1:2:1 Geno Ratio: 1:2:1 Pheno Ratio: 3:1 copyright cmassengale

26. 25 What Do the Peas Look Like? copyright cmassengale

27. 26 …And Now the Test Cross Mendel then crossed a pure & a hybrid from his F 2 generation Mendel then crossed a pure & a hybrid from his F 2 generation This is known as an F 2 or test cross This is known as an F 2 or test cross There are two possible testcrosses: Homozygous dominant x Hybrid Homozygous recessive x Hybrid There are two possible testcrosses: Homozygous dominant x Hybrid Homozygous recessive x Hybrid copyright cmassengale

28. 27 Trait: Seed Shape Trait: Seed Shape Alleles: R – Roundr – Wrinkled Alleles: R – Roundr – Wrinkled Cross: Round seeds x Round seeds Cross: Round seeds x Round seeds RR x Rr RR x Rr F 2 Monohybrid Cross (1 st ) R R rR RR RrRR Rr Genotype:RR, Rr Genotype: RR, Rr PhenotypeRound Phenotype: Round Genotypic Ratio:1:1 Genotypic Ratio: 1:1 Phenotypic Ratio: All alike copyright cmassengale

29. 28 Trait: Seed Shape Trait: Seed Shape Alleles: R – Roundr – Wrinkled Alleles: R – Roundr – Wrinkled Cross: Wrinkled seeds x Round seeds Cross: Wrinkled seeds x Round seeds rr x Rr rr x Rr F 2 Monohybrid Cross (2nd) r r rR Rr rrRr rr Genotype:Rr, rr Genotype: Rr, rr PhenotypeRound & Wrinkled Phenotype: Round & Wrinkled G. Ratio:1:1 G. Ratio: 1:1 P.Ratio: 1:1 copyright cmassengale

30. 29 Mendel’s 3 Laws copyright cmassengale

31. 30 Law of Dominance In a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation. All the offspring will be heterozygous and express only the dominant trait: copyright cmassengale

32. 31 Law of Dominance copyright cmassengale BB x bb produces all Bb Homozygous Dominant Homozygous recessive

34. 33 Law of Segregation During the formation of gametes (eggs or sperm), the two alleles coding for the same trait separate from each other when the chromosomes separate. copyright cmassengale

35. 34 Law of Segregation copyright cmassengale Alleles for a trait are then "recombined" at fertilization, producing the genotype for the offspring.

36. 35 Law of Independent Assortment Alleles for different traits are distributed to sex cells (& offspring) independently of one another (DIFFERENT TRAITS ARE INHERITED SEPARATELY) This law can be illustrated using dihybrid crosses (examine two different traits). copyright cmassengale Yellow round peas Yellow wrinkled peas Green round peas Green wrinkled peas

37. 36 Dihybrid Cross Traits: Seed shape & Seed color Alleles: R: round r: wrinkled Y: yellow y: green RrYy x RrYy All possible gamete combinations F-O-I-L

38. Dihybrid Cross 2 Traits: Seed shape & Seed color Alleles: R: round Y: yellow r: wrinkled y: green Phenotype Combo’s # RrYy x RrYy ____ Gamete list

39. 38 Dihybrid Cross Round/Yellow: 9 Round/green: 3 wrinkled/Yellow: 3 wrinkled/green: 1 Phenotypic ratio is 9:3:3:1

40. 39 Incomplete Dominance and Co-dominance Non-Mendelian Genetics

41. Incomplete Dominance When 2 dominant genes blend together to form a new trait. EX: Red flower + White flower= Pink flower

42. Incomplete Dominance is like laundry

43. Recognize… 3 rd phenotype is “in the mix” now. The offspring looks different from both parents. Both traits are dominant so we use the first letter from each trait, both capital letters. For example: Red flower =R White flower=W RR= Red WW=White RW or WR= Pink

44. Cross a Red and White flower:

45. Let’s try this… 1. Curly hair and Straight hair show incomplete dominance. When they are mixed, we get wavy hair. What hair types could we get if we mixed a wavy haired mother with a curly haired father? 2. Key: 3. ________X________ 4. Curly: Straight: Wavy:

46. And again… 1. Black chickens and white chickens are incomplete dominant. When mixed they make grey chickens. Cross 2 grey chickens. 2. Key:3. _______X_______ 4. Black: White: Grey :

48. Do you know what this is called?

49. Co-Dominance “Co” means “together” When two traits are dominant and they both are expressed together. Written the same way as incomplete dominance! ◦ Ex: a black chicken and a white chicken make a checkered chicken.

50. Give this a try… 1. Roan horses are a co-dominant trait. When you cross a white horse and a red horse, you get a roan horse. What are the chances of getting a roan horse if we cross a red horse and a roan horse? 2. Key:3. _______X_______ 4. Black: White: Grey :

51. Up close…

52. Do you see anything?

53. Sex-Linked Traits Traits that are carried on the sex (X) chromosome. ◦ Examples:  Colorblindness  Baldness  Ear hair  Muscular dystrophy

54. Color-blindness affecting what you see

55. Sex-Linked example: Colorblindness Allele = a little “r” XX= normal X r X= carrier X r X r = colorblind XY= normal X r Y= colorblind

56. Sex Linked Traits – attached to the X chromosome

57. Males only need one copy of the allele, females need two copies to be affected. Mostly males will be affected. ***If mom expresses the sex-linked trait, all of her sons will also express the trait because males get their X chromosome from their mom.**** Recognizing sex-linked traits

58. 57 Sex-linked Traits Example Sex Chromosomes XX chromosome - femaleXY chromosome - male fruit fly eye color Example: Eye color in fruit flies (either red or white eyes) copyright cmassengale

59. 58 Sex-linked Trait Practice Problem Example: Eye color in fruit flies (red-eyed male) x (white-eyed female) X R Y x X r X r Remember: the Y chromosome in males does not carry traits. RR = red eyed Rr = red eyed rr = white eyed XY = male XX = female XRXR XrXr XrXr Y copyright cmassengale

60. 59 Sex-linked Trait Solution: X R X r X r Y X R X r X r Y 50% red eyed female 50% white eyed male XRXR XrXr XrXr Y copyright cmassengale

61. Let’s try this together… What are the chances of having a colorblind child if we cross a carrier mother with a normal father?

62. Try this… Colorblindness is a recessive sex-linked trait. What are the chances of getting a colorblind child if mom is a carrier and dad is colorblind?

63. Try this one on your own… Ear hair is a recessive sex-linked trait carried on the X chromosome. What are the chances of getting a carrier if we cross a man with ear har and a normal woman?

64. And this one… Baldness is a recessive sex-linked trait carried on the X chromosome. What are the chances of getting a bald child if we cross a normal mom and a bald dad?

65. O ii A I A I A or I A i B I B I B or I B i AB I A I B Multiple Alleles More than two different alleles can exist for a particular trait, but only two can be present at any given time (because one allele from each parent). ◦ Ex. Blood Types – three alleles are i, I A, and I B  This is how you can have A, B, AB, or O type blood. Phenotype Genotypes

66. Blood Type Cross I A I B I B i I A I B I B I B I A i I B i

67. AO B O ABBO AOOO Offspring Phenotypes: ¼ Type A ¼ Type B ¼ Type AB ¼ Type O Parents: AO x BO

68. Karyotype

69. Nondisjunction When chromosomes don’t properly separate during meiosis

70. What’s supposed to happen… 1. All chromosomes are copied 2. Homologous pairs form tetrads 3. Homologous pairs separate (meiosis I) 4. Sister chromatids separate (meiosis II) Results in 4 cells with one copy of each chromosome (haploid gametes)

72. When things go wrong… Part 1 The homologous chromosomes don’t separate during anaphase I Both chromosomes go to the same cell Results in 2 gametes with two copies of a chromosome and 2 gametes with no copies of that chromosome

73. Homologous chromosome s fail to separate in meiosis I

74. When things go wrong…Part 2 The sister chromatids don’t separate correctly during anaphase II Both chromatids go to the same cell Results in one gamete with two copies of the chromosome, one gamete with no copies of the chromosome, and two normal gametes

75. Sister chromatids fail to separate during anaphase II

76. What is a Karyotype? A Karyotype is a map of a person’s chromosomes (DNA and genes) There are 23 pairs of chromosomes for a total of 46 chromosomes You can tell if the person is a boy or a girl You can tell if the person has any genetic problems

77. Boy or Girl? Look at the last pair (#23) of chromosomes ◦ XX= Girl ◦ XY= Boy ◦ The X is always bigger than the Y.

78. Down’s Syndrome There is an extra chromosome on #21 ◦ Called Trisomy 21 ◦ Total of 47 Chromosomes ◦ Causes heart problems ◦ Causes mental retardation ◦ Different physical features.

79. Down’s Syndrome

80. Klinefelter’s Syndrome Males have an extra X chromosome 47 total chromosomes Males won’t go through puberty They will never be able to have children

81. Klinefelter’s Syndrome

82. Turner’s Syndrome Females that are missing an X chromosome Total of 45 chromosomes Females never go through puberty Females will never have children

83. Turner’s Syndrome

84. Pedigree A Pedigree is a family tree of a person’s genes.

85. Pedigree Key = male = female = shows the recessive trait = Shows the dominant trait

86. Recognizing recessive traits: Look for 2 unaffected parents with an affected child. Look for traits to skip a generation

87. Recognizing sex-linked traits Mostly males will be affected. If mom expresses the sex-linked trait, all of her sons will also express the trait.

88. Sex-linked or Recessive?

89. Sex-linked or recessive?