HEREDITY = The passing of traits from parents to offspring. Transmitted by means of information stored in molecules of DNA.

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2 HEREDITY = The passing of traits from parents to offspring. Transmitted by means of information stored in molecules of DNA.

3 GENEITCS =Scientific study of heredity Based on knowledge that traits are transmitted by chromosomes. Our chromosomes are made up of our genes, which are pieces of DNA that code for certain traits.

4 Humans have 46 chromosomes in all your somatic (body) cells. 23 chromosomes from your mom and 23 chromosomes from your dad.

5 With MENDELIAN traits (the type of traits that Mendel studied), heterozygotes DO NOT have a blend of the two alleles. Instead, one type of allele dominates We show the characteristics of this allele only it is the DOMINANT trait.

6 The other version of the trait is still there on half of our chromosomes (so we might still pass it on to our children, depending on meiosis) BUT it DOES NOT affect us right now it is the RECESSIVE trait.

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8 Whether we are heterozygous(ex. Tt), Homozygous with the dominant trait(ex. TT), or homozygous with the recessive trait (EX. tt) it is called our GENOTYPE (type of genes that we have). Which trait we physically show is our PHENOTYPE (the type of allele that is expressed).(ex. Blue eyes)

9 Mendel produced pure strains by allowing the plants to self-pollinate for several generations. These strains were called the parental generation or P 1 strain.

10 Mendel cross-pollinated two strains tracked each trait through two generations. (ex: TT x tt ) and Trait = plant height Alleles = T (tall), t (short)

11 P 1 cross = TT x tt t t T Tt Tt T Tt Tt F 1 Genotypic ratio = 100% Tt (4/4) F 1 Phenotypic ratio 100% Tall (4/4) =

12 t T Tt T Tt The offspring of this cross were all hybrids showing ONLY the t Tt Tt dominant trait & were called the First Filial or F 1 generation.

13 Mendel then crossed two of his F 1 plants and tracked their traits; known as an F 1 cross. Trait = plant height Alleles = T (tall), t (short)

14 F 1 cross = Tt x Tt T t T TT Tt t Tt tt F 2 Genotypic ratio = 1/4 TT: 2/4 Tt: 1/4 tt F Phenotypic ratio = 2 3 Tall: 1 short (3/4 tall; ¼ short)

15 When 2 hybrids were crossed, 75% (3/4) of the offspring showed the dominant trait & 25% (1/4) showed the recessive trait Two hybrids ALWAYS create a 3(dominant trait): 1 (recessive trait) ratio. The offspring of this cross were called the F 2 generation.

16 Inheritable factors or genes are responsible for all heritable characteristics. Phenotype is based on genotype.

17 Each trait is based on two genes, one from the mother and the other from the father. True-breeding individuals are homozygous (both alleles) are the same. Formulated 3 laws of heredity in the early 1860's.

18 1. Law of Dominance states that when different alleles for a characteristic are inherited (heterozygous), the trait of only one (the dominant one) will be expressed. The recessive trait's phenotype only appears in truebreeding (homozygous) individuals.

19 Trait: Pod Color Genotypes: GG Gg gg Phenotype: Green Pod Green Pod Yellow Pod

20 2. The Law of Segregation = states that each genetic trait is produced by a pairof alleles which separate (segregate) during reproduction. Rr R r Explains the disappearance of a specific trait in the F 1 generation and its reappearance in the F 2 generation.

21 3. The Law of Independent Assortment= states that each factor (gene) is distributed (assorted) randomly and independently of one another in the formation of gametes (egg or sperm). RrYy RY Ry ry ry

22 Explains that different traits are inherited independently, if on different chromosomes Ex: wrinkled seeds do not have to be yellow. They can be green.

23 Ex: A gamete with RrYy R and r gametes separate into different Y and y Separate into different gametes They can then recombine 4 ways to form gametes: RY Ry ry ry

24 Use Punnett Squares to solve genetic problems!

25 You cannot tell by looking at an organism that shows the dominant trait whether it is heterozygous (Rr) or homozygous(rr) for that trait To determine the genotype of an organism showing the dominant trait a test cross would be done. Test cross = the organism of unknown dominant genotype is crossed with a homozygous recessive (rr) organism.

26 Black coat color in guinea pigs is dominant over white coat color. Using a Punnett square, show the results of crossing a hybrid black with pure white. Then show the results of crossing a hybrid black and a hybrid black.

27 Black Trait B (dominant) White Trait b (recessive) Hybrid black Bb Pure white bb

28 P 1 cross: B b Bb b Bb Bb x bb b bb bb Genotypes of F 1 offspring 2/4 Bb 2/4 bb Phenotypes of F 1 offspring 2 black : 2 white (or 50% black and 50% white)

29 P 1 cross: B B BB Bb Bb x B _ b _ Genotypes of F 1 offspring 1/4BB: 2/4Bb: 1bb b Bb bb Phen/4otypes of F 1 offspring 3Black: 1white

30 1.) In pigs, the white color (W) is dominant; the black color (w) is recessive. Using Punnett squares, show the expected results of the following crosses. (smartboard)

31 P 1 cross: W W_W_ x W w_w_ F G: 1 100% Ww w Ww Ww F P: 1 100% White w Ww Ww

32 P 1 cross: W_w x W_w _ W w W w 1WW: 2Ww: 1ww F 2 G: WW Ww Ww ww F 2 P: 3White: 1black

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34 Because each parent and offspring are using two traits, each one should have 4 alleles, 2 for each trait. Each gamete produced by generations will contain 2 each trait. the P 1 alleles, one for

35 Example: A plant that is heterozygous for being tall and having green seeds is crossed with a homozygous yellow and short Traits = seed color and plant height Alleles G =green T = tall g = yellow t = short Cross: TtGg x ttgg

36 Determine the gametes produced by each parent by using the FOIL method. TtGg produces 4 different gametes: TG Tg tg tg ttgg produces only 1 gamete: tg

37 tg tg TG Tg tg tg TtGg Ttgg ttgg ttgg TtGg Ttgg ttgg ttgg Phenotypes: 4 tall/green seeds 4tall/yellow seeds 4short/green seeds 4short/yellow seeds tg tg TtGg TtGg Ttgg ttgg ttgg Ttgg ttgg ttgg Genotypes: 4TtGg: 4Ttgg: 4ttGg: 4ttgg

38 Smart board practice The father has black hair (heterozygous) and brown eyes (heterozygous) and the mother has blonde hair and blue eyes. Genotype Genotype of father = of mother = Probability AND rule: If you want to know the probability of 2 traits happening at the same timeyou MULTIPLY the probability of the two traits together.