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Chapter 10 - Genetics. What is Genetics? The study of heredity The study of heredity Heredity: passing of traits from parent to offspring Heredity: passing.

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Presentation on theme: "Chapter 10 - Genetics. What is Genetics? The study of heredity The study of heredity Heredity: passing of traits from parent to offspring Heredity: passing."— Presentation transcript:

1 Chapter 10 - Genetics

2 What is Genetics? The study of heredity The study of heredity Heredity: passing of traits from parent to offspring Heredity: passing of traits from parent to offspring

3 Study of Genetics Children inherit traits Children inherit traits Need to study many generations Need to study many generations

4 Review: Genes Section of DNA on chromosomes Section of DNA on chromosomes Paired Paired 1 from mom & 1 from dad 1 from mom & 1 from dad

5 Gregor Mendel (1857) Father of Genetics Father of Genetics Discovered patterns of inheritance by breeding pea plants Discovered patterns of inheritance by breeding pea plants

6 Mendels Experiments Why pea plants? Why pea plants? Easy to grow & can be self pollinated Easy to grow & can be self pollinated Hypothesized that factors carry information about traits Hypothesized that factors carry information about traits

7 Flower Anatomy

8 Mendels Laws Independent Assortment: traits are not inherited together Independent Assortment: traits are not inherited together Segregation: Alleles separate when gametes are formed Segregation: Alleles separate when gametes are formed

9 What We Know Now Factors are called genes Factors are called genes Different forms of a gene are called alleles Different forms of a gene are called alleles Represented by letters Represented by letters Ex. flower color alleles P (purple) or p (white) P (purple) or p (white)

10 Alleles Capital letter = dominant allele Capital letter = dominant allele Ex. P (purple) Ex. P (purple) Lower case = recessive allele Lower case = recessive allele Ex. p (white) Ex. p (white)

11 Important Vocabulary Genotype = alleles (letters) that make up that trait Genotype = alleles (letters) that make up that trait Ex. PP Ex. PP Phenotype = physical appearance of trait Phenotype = physical appearance of trait Ex. Purple Ex. Purple

12 Homozygous: two of the same alleles (a.k.a. purebreed) Homozygous: two of the same alleles (a.k.a. purebreed) Ex. PP or pp Ex. PP or pp Heterozygous: two different alleles (a.k.a. hybrid) Heterozygous: two different alleles (a.k.a. hybrid) Ex. Pp Ex. Pp Important Vocabulary (Cont.)

13 Inheritance Of Traits If you inherit one dominant allele the recessive allele will not be expressed If you inherit one dominant allele the recessive allele will not be expressed

14 Predicting Our Traits Punnett squares show possible genotypes Punnett squares show possible genotypes

15 Setting up a Punnett Square g g G = Green g = White Alleles from Mother Alleles from Father

16 Interpreting Punnett Squares GG g g Gg Offspring

17 Interpreting Punnett Squares (Cont.) Offspring are: Offspring are: 100 % Heterozygous 100 % Heterozygous Their genotype is Gg Their genotype is Gg Their phenotype is green Their phenotype is green

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21 Monohybrid Cross: Punnett Squares that analyze only one trait: Punnett Squares that analyze only one trait: Depending on the parents alleles they can produce 1 or 2 different gametes for that trait. Depending on the parents alleles they can produce 1 or 2 different gametes for that trait.

22 Dihybrid Cross: Punnett Squares that analyze two traits: Punnett Squares that analyze two traits: If both parents are homozygous for the two traits only one gamete can be formed (all heterozygous). If both parents are homozygous for the two traits only one gamete can be formed (all heterozygous).

23 Dihybrid Continued: If parents are heterozygous for the two traits than 4 types of alleles from male gametes and of alleles from female gametes can be formed. If parents are heterozygous for the two traits than 4 types of alleles from male gametes and 4 types of alleles from female gametes can be formed.

24 Phenotypic Ratio is : Phenotypic Ratio is :9:3:3:1 Genotypes: almost all different!

25 Probability Measure of how likely something will occur Measure of how likely something will occur Ex. What is the probability of getting heads when you flip a coin? Ex. What is the probability of getting heads when you flip a coin? Ans. 50% Ans. 50%

26 Punnett squares used to predict the probability of inheriting a trait! Punnett squares used to predict the probability of inheriting a trait! Actual data not perfect- larger # of offspring more likely match the results predicted. Actual data not perfect- larger # of offspring more likely match the results predicted. Probability

27 Recessive Genetic Disorders Need to inherit two copies of recessive allele Need to inherit two copies of recessive allele Tay Sachs Tay Sachs Sickle Cell Anemia Sickle Cell Anemia

28 More Recessive Genetic Disorders Cystic Fibrosis Cystic Fibrosis Albinism Albinism Galactosemia Galactosemia

29 Dominant Genetic Disorders Only need 1 copy of dominant allele Only need 1 copy of dominant allele Polydactyly, Polydactyly, Marfan Syndrome

30 More Dominant Genetic Disorders Huntingtons Disease Huntingtons Disease Achondroplasia Achondroplasia

31 Ch 11.2 Complex Patterns of Inheritance Most traits are not simply dominant or recessive Most traits are not simply dominant or recessive

32 Incomplete Dominance Dominant & recessive traits appear to "blend" Dominant & recessive traits appear to "blend" Ex. snapdragon flowers red x white = pink RR rr Rr

34 A gray cat is crossed with another gray cat and black is incompletely dominant over white. Complete a Punnett square and tell me what is the genotypic and phenotypic ratio of that cross? Incomplete Dominance Phenotypic ratio: Genotypic ratio:

35 Codominance Two traits are both fully seen Two traits are both fully seen Co= together Ex. Roan Horses have both red & white hairs

36 Codominance Both alleles should be Capital letters since one is not dominant over another. Cross: Roan Horse X Red Horse RW R R R RW RW RRWRW

37 Codominance In humans, wavy hair (CS) results by the co-dominance pattern of curly hair (C) and straight hair (S). What are the possible results if a wavy-haired man and a straight-haired woman have children? List Genotypic and Phenotypic Ratios!

38 Multiple Alleles Two or more alleles control the phenotype Two or more alleles control the phenotype Ex. Human ABO blood groups Ex. Human ABO blood groups

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41 Multiple Alleles A woman with type B (heterozygous) blood and a man with type AB blood are expecting a child. What are the possible blood types of the kids?

42 A test was done to determine the biological father of a child. The childs blood Type is B and the mothers is Type A. Dude #1 has blood type O and dude # 2 has blood type AB. Which dude is the biological father? Multiple Alleles

43 Polygenic Traits Traits that are controlled by multiple genes Traits that are controlled by multiple genes Ex. height, weight, hair color, skin color Ex. height, weight, hair color, skin color

44 Skin Color At least 7 different Genes make up skin color!

45 Eye Color

46 Sex-Linked Traits Carried on sex chromosomes (X and Y) Carried on sex chromosomes (X and Y) Most are recessive & on X chromosome Most are recessive & on X chromosome Color blindness, hemophilia Color blindness, hemophilia

47 Affect men more than women Affect men more than women Men have only one X chromosome Men have only one X chromosome Women can be carriers or affected Women can be carriers or affected Sex-Linked Traits (cont.)

48 Sex Chromosomes for Female are: X Sex Chromosomes for male are: X Y Sex-Linked Traits (cont.)

49 Fruit fly eye Color R = Red eyes r or w = white eyes What is the probability of having a white eyed male? Sex-Linked Traits (cont.)

50 A female fruit fly that is homozygous for red eyes mates with a male who has white eyes. What is the probability of having a female with white eyes? Sex-Linked Traits (cont.)

51 A woman who is heterozygous for colorblindness has a son with a man who is colorblind. What is the probability that their son will be colorblind? Sex-Linked Traits (cont.)

52 Polyploidy One or more extra chromosomes. 2n = normal number of chromosomes Humans 46 chromosomes/ 23 pairs 1n = half the number of chromosomes Sperm or Egg 23 chromosomes

53 Triploid (3n)– 3 complete sets of chromosomes = 69 Most plants; sometimes earthworms and goldfish; Humans always Lethal! Polyploidy

54 Karyotype: photographic arrangement of a complete set of chromosomes Karyotype: photographic arrangement of a complete set of chromosomes Studying Inheritance

55 FROM THIS……..

56 ……TO THIS

57 Chromosomes # 1-22 are autosomes (body chromosomes) Chromosomes # 23 are the sex chromosomes. Looking at a karyotype you can see a chromosome mutation. Studying Inheritance

58 ______Chromosomal________ Abnormalities 1 infant in 200 newborns has a chromosomal abnormality 28% of first trimester miscarriages have a chromosomal abnormality Abnormalities in larger chromosomes dont usually survive

59 ____________________________: Change in the ______________ or ____________ of chromosomes CHROMOSOMAL MUTATIONS structure number

60 Homologous chromosomes ________________ during MEIOSIS = _________________________ One cell gets 2 copies of the chromosome the other cell gets none. NONDISJUNCTION fail to separate

61 Nondisjunction

62 Nondisjunction can lead to: Down Syndrome Turners Syndrome Klinefelters Syndrome

63 Down syndrome (=____________) TRISOMY 21

64 Down syndrome (Trisomy 21) 1 in 800 births Similar facial features Slanted eyes Protruding tongue

65 Turner syndrome

66 Turner syndrome ____ 1 in 5000 births Females have only one X chromosome Small size Slightly decreased intelligence 35% have heart abnormalities Hearing loss common Broad chest Reproductive organs dont develop at puberty Cant have children XO

67 Klinefelter syndrome XXY

68 Klinefelter syndrome 1 in 1000 births Males have extra X chromosomes (Can be XXy, XXXy, or XXXXy) Average to slight decrease in intelligence Small testes/cant have children Usually not discovered until puberty when dont mature like peers

69 Obtaining Fetal Cells ~Making a Karyotype~ 1.Amniocentesis: sample of fluid around baby 2.Chorionic Villus Sampling: sample of tissue from the placenta

70 Amniocentesis

71 Chorionic Villus Sampling

72 Pedigree: chart that tracks the inheritance of a trait through multiple generations Pedigree: chart that tracks the inheritance of a trait through multiple generations Studying Inheritance (cont.)

73 Generation Symbols P = Parental P = Parental F 1 = Offspring of P generation F 1 = Offspring of P generation F 2 = Offspring of F 1 generation F 2 = Offspring of F 1 generation

74 P Generation F 1 Generation F 2 Generation Generation Symbols (cont.)

75 Interpreting the Pedigree CarrierAffectedMaleFemale

76 Dominant Disorder Example:

77 Recessive Pedigree Example:

78 Create A Pedigree: One couple has a son and a daughter with normal pigmentation. Another couple has one son and two daughters with normal pigmentation. The daughter from the first couple has three children with the son of the second couple. Their son and one daughter have albinism; their other daughter has normal pigmentation. One couple has a son and a daughter with normal pigmentation. Another couple has one son and two daughters with normal pigmentation. The daughter from the first couple has three children with the son of the second couple. Their son and one daughter have albinism; their other daughter has normal pigmentation.


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