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Genetics History.

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Presentation on theme: "Genetics History."— Presentation transcript:

1 Genetics History

2 Directions: I am going to roll 6 dice…one at a time. In order, write the numbers you think I will roll. If correct, you will win a prize.

3 What were the odds of you winning?
Pretend these were the numbers you guessed. What are the odds the 1st number is 5? 2nd number is 2? 3rd number is 6? 4th number is 5? 5th number is 1? 6th number is 3? How do you calculate the overall odds? 1 6 1 6 1 6 1 6 1 6 1 6 X X X X X 1 46,656 = %

4 What is Genetics? Genetics: Study of heredity
Heredity: passing of traits from parent to child (offspring) Gregor Mendel Austrian monk Uncovered pattern for how traits can be passed from generation to generation

5 Mendel’s 7 traits studied

6 Mendel’s Experiment P Generation: F1 Generation:
Male: purple flowers Female: Purple flowers F1 Generation: 100% purple Learned? Traits are inherited from parents male female F1 Generation

7 Mendel’s Experiment P Generation: F1 Generation: Male: white flowers
Female: white flowers F1 Generation: 100% white male female F1 Generation

8 Mendel’s Experiment P Generation: F1 Generation: Learned?
Male: purple flowers Female: White flowers F1 Generation: 100% purple Learned? Some traits are dominant Some traits are recessive P Generation male female F1 Generation

9 Mendel’s Experiment F1 Generation: F2 Generation: Learned?
Male: purple flowers Female: Purple flowers F2 Generation: 75% purple 25% white Learned? Offspring won’t always resemble the parents Traits can skip generations male female Remember… these had a white parent F2 Generation F1 Generation

10 Mendel’s 7 traits studied

11 Each trait had a 3:1 ratio. No way that can be a coincidence!

12 Common Vocabulary P P Genotype: combination of two alleles
Gene for dominant purple flowers Gene for dominant purple flowers Genotype: combination of two alleles An allele is a version of a gene. Homozygous Dominant: combination of 2 dominant alleles P P Homozygous dominant allele

13 Common Vocabulary p p Genotype: combination of two alleles
Gene for recessive white flowers Gene for recessive white flowers Genotype: combination of two alleles Homozygous Dominant: combination of 2 dominant alleles Homozygous Recessive: combination of 2 recessive alleles p p Homozygous recessive allele

14 Common Vocabulary P p Genotype: combination of two alleles
Gene for dominant purple flowers Gene for recessive white flowers Genotype: combination of two alleles Homozygous Dominant: combination of 2 dominant alleles Homozygous Recessive: combination of 2 recessive alleles Heterozygous: Combination of 1 dominant, 1 recessive allele P p Heterozygous allele

15 pp Common Vocabulary PP Pp Genotype: combination of two alleles
Homozygous Dominant: combination of 2 dominant alleles Homozygous Recessive: combination of 2 recessive alleles Heterozygous: Combination of 1 dominant, 1 recessive allele Phenotype: Physical expression of the gene PP Phenotype: PURPLE flowers Pp Phenotype: pp White Flowers

16 30 Seconds: Discuss with your neighbor:
Choices: YY Tall Yy SS yY gg Smooth Green TT Dwarf Which choice(s) are examples genotypes?

17 30 Seconds: Discuss with your neighbor:
Choices: YY Tall Yy SS yY gg Smooth Green TT Dwarf Which choice(s) are examples heterozygous genotypes?

18 30 Seconds: Discuss with your neighbor:
Choices: YY Tall Yy SS yY gg Smooth Green TT Dwarf Which choice(s) are examples phenotypes?

19

20 Punnett Squares p p P P P P P P 100% p p p p
Homozygous dominant Homozygous recessive Defined: Genetics tools used to predict offspring probability Setting Up Punnett Squares: 1) Parent genotypes on outside of the squares 2) Simply fill in each square 3) Inside squares represent the possible offspring genotypes Probability of growing purple flowers? p p P P P p P p P p P p 100%

21 P p P P P P p P p p p p 1) List the genotypes. PP, Pp, pp
1 minute: Cross a heterozygous purple (Pp) plant with another heterozygous purple (Pp) plant P 1) List the genotypes. 2) List the phenotypes. 3) What is the probability of having a white plant? p PP, Pp, pp P P P P p purple and white P p p p p 25%

22 Autosomal Recessive Inheritance
Hh Hh Autosome: Non-sex chromosome Autosomal disorders are caused by genes found on the non-sex chromosomes ex: Sickle cell = chromosome #11 ex: Cystic fibrosis = chromosome #7 Sufferers must inherit 2 alleles to have the disease H = healthy h = disease H H h H h h healthy Healthy (carrier) disease

23 1 Minute: Maria is a heterozygous healthy (Hh) female and Jeff suffers from recessive cystic fibrosis (hh). h h Key H = healthy h = cystic fibrosis H H h H h h h h h h 1) Probability of having a healthy child? _________ 2) Probability of having a homozygous dominant child? ________ 50% 0%

24 Quiz 1) How are dominant alleles expressed? Recessive?
2) Which of the following are genotypes? Phenotypes? TT Green yY Pp Purple gg Smooth 3) Which of the following are heterozygous genotypes? 4) Genes may often be found in two forms (dominant and recessive). What are these alternate forms of a gene called? 5) If item A is found in a 2:1 ratio compared to item B, what percentage is item A? 6) If item A is found in a 4:1 ratio compared to item B, what percentage is item A? 7) Cross a heterozygous tall with a homozygous recessive short pea plant. List the genotypes in a Punnett square. What’s the probability of growing a tall plant? What’s the probability of growing a homozygous dominant plant? What’s the probability of growing a homozygous recessive plant?


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