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Probability and Genetics pg. 656-666 b Objectives: b Describe the principles of probability and how Mendel applied them to inheritance b State how geneticists.

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Presentation on theme: "Probability and Genetics pg. 656-666 b Objectives: b Describe the principles of probability and how Mendel applied them to inheritance b State how geneticists."— Presentation transcript:

1 Probability and Genetics pg b Objectives: b Describe the principles of probability and how Mendel applied them to inheritance b State how geneticists use Punnett squares

2 Vocabulary b probability b Punnett square b phenotype b genotype b homozygous b heterozygous b codominance

3 Questions b How are punnet squares useful to geneticists? b What is the difference between a genotype and a phenotype? b A white cow is crossed with a red bull. The calf is neither white nor red, but roan. Explain how this happens!

4 What was the chance of Pettygrove winnng the coin toss? b Probability- the liklihood that a particular event will occur.

5 Heads up Tails up -equally likely to occur -equally likely to occur

6 Math terms b Probability that coin will land heads up is 1 in 2 b Probability that coin will land tails up is 1 in 2 1/2 or 50 %

7 Toss a coin 20 times b Likely or Expect: 10 heads up / 10 tails up b Will occur: 11 heads / 9 tails or 8 heads / 12 tails 8 heads / 12 tails Laws of probability is what is ‘likely’ to occur.

8 When you toss a coin more than once the results of one toss do not affect the results of the next toss. ? Is it more likely to land tails ?

9 NO. -Still have a 1 in 2 or 50% chance of landing heads.

10 Is ‘Probability’ related to ‘Genetics’ ? b Yes! b It can help predict the results of ‘Genetic Crosses’  Remember Mendel ? (the guy in a dress) b T x T = T T T T b t x t = t t t t  T x t = T T T t 1/4 will be short, 3/4 will be Tall

11 Cool Tool Punnett Square-shows all the possible combinations of alleles that can result from a genetic cross. b Possible combination of alleles that parents can pass on b Possible combinations of alleles that offspring can inherit b All by chance b 4 possible combinations T 25% T t 25% T t 25% t 25% Tt T t

12 You can predict 100 % will be Red

13 Organism with Bb alleles Bb B b BB Bb bb

14 Other Genetic Terms to use b Phenotype-physical appearance, visible traits ex: traits you can see b Genotype-genetic make- up ex: traits you can’t see b Homozygous-identical alleles ex: T T or t t, Not purebred b Heterozygous-two different alleles ex: Tt or hybrid PhenotypeGenotype Tall T T Tall T t Short t t

15 EXCEPTION b Remember Mendel only found Dominant and recessive genes b Codominance-alleles are neither dominant or recessive b no masking takes place b Sooooo…….. b Red Reindeer + white Reindeer =

16 Pink Reindeer ! YIKES !

17 Probability Quiz b 1. An organisms’ genetic makeup, or allele combinations. b 2. An organism’s physical appearance, or visible traits. b 3. The likelihood that a particular event will occur. b 4. Having two identical alleles for a trait. b 5. A chart that shows all the possible combinations of alleles that can result from a genetic cross. b 6. Having two different alleles for a trait. b 7. A condition in which neither of two alleles of a gene is dominant or recessive.

18 Questions: b 8. How are punnet squares useful to geneticists? b 9. What is the difference between a genotype and a phenotype? b 10. A white cow is crossed with a red bull. The calf is neither white nor red, but roan. Explain how this happens?

19 Answers to Probability Quiz b 1. genotype b 2. phenotype b 3. probability b 4. homozygous b 5. punnett square b 6. heterozygous b 7. codominance

20 Answers: b 8. Shows possible genetic outcomes of offspring and the probability of each outcome. b 9. Phenotype is the physical appearance, Genotype is the genetic makeup. b 10. Co dominance. ____/10


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