2 1. Probability The likelihood that a particular event will happen For example: A Coin Toss2. A coin has a 50% chance to be heads or tails3. Is the outcome of the flip determinant on past flips?No!
3 Probability and Genetics How does probability effect genetics?The Segregation of Alleles4. When alleles segregate it is completely random, very similar to a coin toss.Interesting to think of how things could have been different don’t you think?
4 The Punnett Square5. Allows possible gene combinations to be predicted by the use of a diagramCan be used to predict and compare genetic variations that will result from a crossAs well as the probability of occurance
6 8. Homozygous Having two identical alleles for a particular trait Ex: TT or tt“True-Breeding” fora Particular TraitExamples:HydrasMushroomsBacteria
7 10. HeterozygousOrganisms having two different alleles for the same traitEx: Tt“Hybrids” for a particular traitExamples:Cross Pollinating PlantsMulesThe majority of higherorganisms
8 9. Phenotype The physical characteristics of an organism In our Punnett Square example what are our phenotypes?TallTT or TtShorttt
9 7. Genotype The genetic makeup of an organism In our Punnett Square example what would the genotypes be?TT- 25%Tt- 50%tt- 25%
10 Phenotype VS Genotype: Plant 1: Homozygous (TT)Plant 2: Heterozygous (Tt)12. Just because an organism has the same phenotype, that doesn’t mean it always has the same genotype.
11 13.Probability and Segregation Let’s look at our Hybrid Cross results:14. Mendel’s Requirements for Segregation¾ of plants displayed the Tall phenotype¼ of plants displayed the Short phenotype3:1 ratio of tall to short plantsDid Segregation occur in relation to Mendel’s model?YES!
12 Probabilities Predicting Averages 15.Probabilities predict the average outcome of large scale events, BUT not precise individual events16. For example: Coin TossYou can get 50:50 ratio but it could take you numerous tossesAre the odds in our favor for just 2 tosses?
13 Probabilities Predicting Averages 17. The larger the number of offspring in a genetic cross, the better chances that the values will show the 3:1 ratio.18. So which would offer the better data?An F1 generation of 100?An F1 generation of 1000?