1. Mendel’s Genetics

2. Where did that blonde hair come from? law of segregation and random assortment 46 23

3. GENETICS and EVOLUTION  The purpose of this chapter is to show how genetic traits are passed from one generation to another. This is called HEREDITY  If there was no genetic variation through mutation or crossing over of genes there would be no evolution

4. Gregor Mendel The Monastery

5. I. Gregor Mendel- the father of genetics theory (1822-1884) A. Background 1. entered monastery at 21 1. entered monastery at 21 2. studied math and science 2. studied math and science at University of Vienna at University of Vienna 3. 1857-1865 – investigated 3. 1857-1865 – investigated inheritance in pea plants inheritance in pea plants

6. B. Peas – A Fortunate Choice (Pisum sagivum) (Pisum sagivum) 1. seven distinct characteristics 1. seven distinct characteristics (flower color, flower position, (flower color, flower position, seed color, seed shape, pod shape, pod color, height) seed color, seed shape, pod shape, pod color, height) 2. easy to grow 2. easy to grow 3. mature quickly 3. mature quickly 4. easy to pollinate 4. easy to pollinate

8. D. Mendel’s Experiments- monohybrid crosses (one purple & one white parent) 1. P 1 Generation (Parental) 1. P 1 Generation (Parental) a. crossed plants pure for a trait – TRUE- BREEDING a. crossed plants pure for a trait – TRUE- BREEDING 2. F 1 Generation (Offsprng of P 1 ) a. all plants show one form of the trait 2. F 1 Generation (Offsprng of P 1 ) a. all plants show one form of the trait 3. F 2 Generation (Offsprng of F 1 ) 3. F 2 Generation (Offsprng of F 1 ) a. show forms of trait in 3:1 a. show forms of trait in 3:1 ratio ratio

9. Mendel’s P, F 1 and F 2 Generations

10. Examples of P 1 Cross Tall X Short (both are pure) T T X t t All offspring are tall (T t) F 1 Generation F 1 Generation (all are hybrids) Purple Flower X White Flower (both pure) P P X p p All offpsring are purple (Pp) F 1 Generation F 1 Generation (all are hybrids)

11. Mendel’s F 1 Cross (hybrid x hybrid) Tall X Tall (hybrid cross) T t X T t 3 tall plants : 1 short plant (F 2 Generation) Ratio of 3:1 Purple Flowers X Purple Flowers (hybrid) P p X P p 3 purple flower plants : 1 white flower (F 2 ) Ratio of 3:1

13. II. Vocabulary A. Dominant (represented by upper case letter) 1. allele that masks the recessive 1. allele that masks the recessive allele for the same characteristic allele for the same characteristic B. Recessive (represented by lower case letter) case letter) 1. allele that is masked by the 1. allele that is masked by the dominant allele for the same dominant allele for the same characteristic characteristic

14. II. Vocabulary C. Genotype C. Genotype 1. genetic makeup 1. genetic makeup 2. examples 2. examples a. TT, Tt, tt, a. TT, Tt, tt, b. PP, Pp, pp b. PP, Pp, pp D. Phenotype 1. external appearance 1. external appearance 2. examples 2. examples a. tall, short a. tall, short b. purple flowers, white flowers b. purple flowers, white flowers

15. E. Homozygous (pure) 1. two alleles code for the same trait 1. two alleles code for the same trait 2. examples 2. examples a. TT, tt, PP, pp a. TT, tt, PP, pp F. Heterozygous (hybrid) 1. two alleles do not code for the 1. two alleles do not code for the same trait same trait 2. examples 2. examples a. Tt and Pp a. Tt and Pp

16. III. Complete Dominance (Monohybrid Cross) A. Both parents are pure 1. homozygous x homozygous 1. homozygous x homozygous 2. example T T x t t 2. example T T x t t B. Both parents are hybrid 1. heterozygous X heterozygous 1. heterozygous X heterozygous 2. example Tt x Tt 2. example Tt x Tt

17. III. Complete Dominance C. Pure parent X hybrid parent 1.homozygous dominant X heterozygous a. Example T T x T t a. Example T T x T t 2.homozygous recessive x heterozygous 2.homozygous recessive x heterozygous a. Example tt x Tt a. Example tt x Tt

18. PUNNETT SQUARES

19. MENDEL”S THEORY  1. Each individual has two copies of an individual trait -these traits controlled by a pair of factors a. today factors are called alleles a. today factors are called alleles 2. There are alternate versions traits  TT = tall tall Tt= tall short tt= short short

20. MENDEL”S THEORY  3. One trait may be expressed and other may not have an effect.  dominant and recessive

22. Analysis of Mendel’s Results Analysis of Mendel’s Results 1. Principle of Dominance a. one factor (gene) can prevent a. one factor (gene) can prevent expression of another (dominance) expression of another (dominance) IE: hybrid tall plant – phenotype- tall genotype- Tt genotype- Tt

23. 2. Law of Segregation 2. Law of Segregation a. a pair of factors separate when gametes form a. a pair of factors separate when gametes form 3. Law of Independent Assortment a. factors (genes) for different a. factors (genes) for different characteristics separate characteristics separate independently independently

24.  WORK ON Inheritance lab

25. Where did that blonde hair come from? law of segregation and random assortment 46 23

26. Incomplete Dominance  The phenotype of an individual is the intermediate trait between the two parents:  Or-When two heterozygous genotypes make a third, different phenotype.  EXAMPLES: Straight haired mother and curly haired father- the child will have an intermediate trait such as wavy hair Straight haired mother and curly haired father- the child will have an intermediate trait such as wavy hair Red snapdragon when crossed with white snapdragons produce pink snapdragons. Red snapdragon when crossed with white snapdragons produce pink snapdragons.

27. 10.5 Do the Mendelian Rules of Inheritance Apply to All Traits?  In incomplete dominance, the phenotype of the heterozygotes is intermediate between the phenotypes of the homozygotes In the genes studied by Mendel, one allele was dominant over the other, which was recessive In the genes studied by Mendel, one allele was dominant over the other, which was recessive Some alleles, however, are incompletely dominant over others Some alleles, however, are incompletely dominant over others When the heterozygous phenotype is intermediate between the two homozygous phenotypes, the pattern of inheritance is called incomplete dominance When the heterozygous phenotype is intermediate between the two homozygous phenotypes, the pattern of inheritance is called incomplete dominance

28. 10.5 Do the Mendelian Rules of Inheritance Apply to All Traits?  In incomplete dominance, the phenotype of the heterozygotes is intermediate between the phenotypes of the homozygotes (continued) Human hair texture is influenced by a gene with two incompletely dominant alleles, H 1 and H 2 Human hair texture is influenced by a gene with two incompletely dominant alleles, H 1 and H 2 A person with two copies of the H 1 allele has curly hairA person with two copies of the H 1 allele has curly hair Someone with two copies of the H 2 allele has straight hairSomeone with two copies of the H 2 allele has straight hair Heterozygotes (with the H 1 H 2 genotype) have wavy hairHeterozygotes (with the H 1 H 2 genotype) have wavy hair

29. 10.5 Do the Mendelian Rules of Inheritance Apply to All Traits?  In incomplete dominance, the phenotype of the heterozygotes is intermediate between the phenotypes of the homozygotes (continued) If two wavy-haired people marry, their children could have any of the three hair types: curly (H 1 H 1 ), wavy (H 1 H 2 ), or straight (H 2 H 2 ) If two wavy-haired people marry, their children could have any of the three hair types: curly (H 1 H 1 ), wavy (H 1 H 2 ), or straight (H 2 H 2 )

30. Figure 10-13 Incomplete dominance H1H2H1H2 father H2H2 sperm mother H1H1 eggs H1H1H1H1 H1H2H1H2 H1H2H1H2 H2H2H2H2 H2H2 H1H1 H1H2H1H2

31. 10.5 Do the Mendelian Rules of Inheritance Apply to All Traits?  A single gene may have multiple alleles An individual may have at most two different gene alleles An individual may have at most two different gene alleles A species may have multiple alleles for a given characteristic A species may have multiple alleles for a given characteristic However, each individual still carries two alleles for this characteristicHowever, each individual still carries two alleles for this characteristic

32. IV. Incomplete Dominance (both alleles influence the trait) A. Pure X Pure = all hybrids 1.example (red flower and white flower) a. RR x WW B. Hybrid X Hybrid 1. e (pink x pink flower)a. RW x RW 1. e (pink x pink flower)a. RW x RW C. Pure X hybrid 1.ex (red x pink or white x pink) 1.ex (red x pink or white x pink) a. RR x RW or WW x RW a. RR x RW or WW x RW

33. Incomplete Dominance Four O’clock Flowers Pink (RW) White (WW) Red (RR)

34. Codominant traits  Both traits are shown – for instance the person with AB blood type is a child with one parents that was A blood type and one parent with B blood type.  Neither trait is dominant. Both are in the genotype and phenotype.

35. V. Codominance (both alleles are expressed) A. Pure X Pure 1. example (white horse x red horse) a. WW x RR 1. example (white horse x red horse) a. WW x RR B. Hybrid x Hybrid 1. example (roan horse x roan horse) a. RW x RW 1. example (roan horse x roan horse) a. RW x RW C. Pure X Hybrid 1. example(redxroan /white xroan) 1. example(redxroan /white xroan) a. RR x RW or WW x RW a. RR x RW or WW x RW

36. VI. Multiple Allele Problems (Blood Types) A. PHENOTYPE Type A Type A Type B Type B Type AB Type AB Type O Type O B. GENOTYPE AA, AO ( I A I A, I A i ) BB, BO ( I B I B, I B i ) AB ( I A I B ) OO ( ii )

40. Blood Donors and Recipients

41. VII. Sex-linked Inheritance (X linked-carried on X chromosome) A. Examples of sex-linked traits 1. color blindness 1. color blindness 2. hemophilia 2. hemophilia 3. muscular dystrophy 3. muscular dystrophy 4. Icthyosis 4. Icthyosis

42. Individual Chromosomes Individual Chromosomes Normal Male Male with Disease Normal Female Female Carrier Female - Disease X Y X Y X* Y X* Y X X X X X* X X* X X* X* X* X*

43. Problem Solving- Sex Linked Diseases A. A man is colorblind and his wife is a carrier for colorblindness. What is the probability that they will have a child who is colorblind? (A son? A daughter?) B. A man and woman are both colorblind. Can they have a child who is not colorblind? (A son? A daughter?)

44.  Website –sex linked traits  www.edc./weblabs www.edc./weblabs  http://www.biology.arizona.edu/mendelian _genetics/problem_sets/sex_linked_inherit ance/sex_linked_inheritance.html http://www.biology.arizona.edu/mendelian _genetics/problem_sets/sex_linked_inherit ance/sex_linked_inheritance.html http://www.biology.arizona.edu/mendelian _genetics/problem_sets/sex_linked_inherit ance/sex_linked_inheritance.html

46. Pedigree-a genetic family tree www.genetics.gsk.com/graphics/autosomal_recessive.gif www.genetics.gsk.com/graphics/autosomal_recessive.gif h tt : / /

47.  Pedigree chart tells us two things 1. WHETHER IT IS AN AUTOSOMAL(22 BODY PAIRS) OR SEX-LINKED (1PAIR OF SEX TRAITS XX OR XY) If male and female is close to equal it is autosomal 1. WHETHER IT IS AN AUTOSOMAL(22 BODY PAIRS) OR SEX-LINKED (1PAIR OF SEX TRAITS XX OR XY) If male and female is close to equal it is autosomal 2. WHETHER IT IS DOM. OR RECESS. TRAIT- IF THE TRAIT IS PASSED TO NEXT GENERATION – BUT SKIPPED A GENERATION IT IS RECESSIVE- 2. WHETHER IT IS DOM. OR RECESS. TRAIT- IF THE TRAIT IS PASSED TO NEXT GENERATION – BUT SKIPPED A GENERATION IT IS RECESSIVE- IF THE PARENTS WERE NORMAL(WERE CARRIERS) AND HAD A CHILD WITH THE TRAIT IT IS RECESSIVE IF THE PARENTS WERE NORMAL(WERE CARRIERS) AND HAD A CHILD WITH THE TRAIT IT IS RECESSIVE

48. Autosomal pedigree chart

49. Sex-linked pedigree

50.  ROYAL FAMILY PEDIGREE

51. Dihybrid Cross  A cross that involves two traits.  Example:  Predict the results of two pea plants that are heterozygous for  seed shape – R-round r-wrinkled  Seed color- Y- yellow y- green

52. 10.4 How Are Multiple Traits Inherited?  Mendel concluded the origination of single traits inheritance  He then pursued more complex questions relative to the inheritance of multiple traits  Initial experiments included crossbreeding plants that differed in two traits Seed color (yellow or green)Seed color (yellow or green) Seed shape (smooth or wrinkled)Seed shape (smooth or wrinkled)

53. Figure 10-10 Traits of pea plants studied by Gregor Mendel Seed shape Seed color Pod shape Pod color Plant size Flower color Flower location TraitDominant formRecessive form smooth wrinkled yellow green yellow green inflatedconstricted white purple at tips of branches at leaf junctions dwarf (about 8 to 16 inches) tall (about 6 feet)

54. 10.4 How Are Multiple Traits Inherited?  From the many pea plant phenotypes, he chose seed color (yellow vs. green peas) and seed shape (smooth vs. wrinkled peas) Yellow color is dominant to green colorYellow color is dominant to green color Smooth shape is dominant to wrinkledSmooth shape is dominant to wrinkled  The allele symbols were assigned, as follows: Y = yellow (dominant), y = green (recessive)Y = yellow (dominant), y = green (recessive) S = smooth (dominant), s = wrinkled (recessive)S = smooth (dominant), s = wrinkled (recessive)

55. 10.4 How Are Multiple Traits Inherited?  The two-trait cross was between two true-breeding varieties for each characteristic, one dominant for both traits, the other recessive for both traits P: SSYY (smooth, yellow)  ssyy (wrinkled, green)P: SSYY (smooth, yellow)  ssyy (wrinkled, green) The SSYY plant produced only SY gametes, and the ssyy plant produced only sy gametesThe SSYY plant produced only SY gametes, and the ssyy plant produced only sy gametes Therefore, the F 1 consisted solely of SsYy individuals, with smooth skins and yellow coloringTherefore, the F 1 consisted solely of SsYy individuals, with smooth skins and yellow coloring

56. 10.4 How Are Multiple Traits Inherited?  Mendel next allowed the F 1 individuals to self- fertilize: SsYy  SsYy  Crossing the F 1 plants yielded 315 plants with smooth, yellow seeds; 101 with wrinkled, yellow seeds; 108 with smooth, green seeds; and 32 with wrinkled, green seeds This is a ratio of approximately 9:3:3:1This is a ratio of approximately 9:3:3:1  Two-trait crosses of other traits produced similar proportions of phenotype combinations

57. Figure 10-11 Predicting genotypes and phenotypes for a cross between parents that are heterozygous for two traits sYsY self-fertilize eggs sy SySy Ss YySs Yy seed shapeseed color phenotypic ratio (9:3:3:1) Using probabilities to determine the offspring of a two-trait cross wrinkled green wrinkled yellow smooth yellow wrinkled   green smooth   green wrinkled   yellow smooth   yellow smooth green SY sYsY sy SySy SY S s YY SsYySsYy SSY y SSYY S sy Y S syy SS yy SS y Y ss YY ss Y y s SY ys SYY ssy Y ssyy s S yy sSyYsSyY Punnett square of a two-trait cross sperm

58. 10.4 How Are Multiple Traits Inherited?  Mendel hypothesized that traits are inherited independently Mendel predicted that if the two traits were inherited independently, then for each trait, three- quarters of the offspring should show the dominant phenotype and one-quarter should show the recessive phenotype Mendel predicted that if the two traits were inherited independently, then for each trait, three- quarters of the offspring should show the dominant phenotype and one-quarter should show the recessive phenotype a 3:1 ratio, as he had found for the single trait flower colora 3:1 ratio, as he had found for the single trait flower color

59. 10.4 How Are Multiple Traits Inherited?  Mendel hypothesized that traits are inherited independently (continued) He found 423 plants with smooth seeds (of either color) and 133 with wrinkled seeds (a ratio of about 3:1) He found 423 plants with smooth seeds (of either color) and 133 with wrinkled seeds (a ratio of about 3:1) He found 416 plants produced yellow seeds (of either shape) and 140 produced green seeds (also about 3:1) He found 416 plants produced yellow seeds (of either shape) and 140 produced green seeds (also about 3:1)

60. 10.4 How Are Multiple Traits Inherited?  Mendel hypothesized that traits are inherited independently (continued) The independent inheritance of two or more traits is called the law of independent assortment The independent inheritance of two or more traits is called the law of independent assortment Multiple traits are inherited independently because the alleles of one gene are distributed to gametes independently of the alleles for other genes Multiple traits are inherited independently because the alleles of one gene are distributed to gametes independently of the alleles for other genes Independent assortment will occur when the traits being studied are controlled by genes on different pairs of homologous chromosomes Independent assortment will occur when the traits being studied are controlled by genes on different pairs of homologous chromosomes

61. 10.4 How Are Multiple Traits Inherited?  Mendel hypothesized that traits are inherited independently (continued) The physical basis of independent assortment has to do with the way homologous pairs line up during meiosis The physical basis of independent assortment has to do with the way homologous pairs line up during meiosis Which of the two homologues is “on top” occurs randomly for all pairs, so the homologues assort randomly and independently of one another at anaphase I Which of the two homologues is “on top” occurs randomly for all pairs, so the homologues assort randomly and independently of one another at anaphase I

62. Animation: The Inheritance of Multiple Traits

63. Figure 10-12 Independent assortment of alleles Y S independent assortment produces four equally likely allele combinations during meiosis pairs of alleles on homologous chromosomes in diploid cells replicated homologous pair during metaphase of meiosis I, orienting like this or like this chromosomes replicate meiosis I meiosis II y s Y S y s Y S y s Y S y s Y S y s Y S y s Y S y s Y S y s Y S y s y s Y S S y Y s SySy sYsY SY sy

64. 10.4 How Are Multiple Traits Inherited?.  In an unprepared world, genius may go unrecognized Mendel’s work was published in 1865 but went unnoticed Mendel’s work was published in 1865 but went unnoticed Three biologists—Carl Correns, Hugo de Vries, and Erich Tschermak—independently (of Mendel and each other) rediscovered Mendel’s principles of inheritance in 1900 Three biologists—Carl Correns, Hugo de Vries, and Erich Tschermak—independently (of Mendel and each other) rediscovered Mendel’s principles of inheritance in 1900 Mendel was credited in new papers as laying the groundwork of genetics 30 years previously Mendel was credited in new papers as laying the groundwork of genetics 30 years previously

65. 10.5 Do the Mendelian Rules of Inheritance Apply to All Traits?  Each trait is completely controlled by a single gene  Only two possible alleles of each gene exist  One allele is completely dominant to the other, recessive, allele  Most traits are influenced in more varied and subtle ways

66. Dihybrid cross  Parent- round and yellow RrYy RrYy

67. Dihybrid Cross

69.  Fill in all the genotypes for the previous slide.