1. 1 Review What is probability Use Models How are Punnett squares used to predict the outcomes of genetic crosses 2 Review What is independent assortment Calculate An F1 plant that is homozygous for shortness is crossed with a heterozygous F1 plan. What is the probability that a seed from the cross will be tall. Use a Punnett Square to explain your answer and to compare the probable genetic variations in the F2 plants 3 Review How did Gregor Mendel contribute to our understanding of inherited traits Apply Concepts Why is the fruit fly an ideal organism for genetic research

2. Ch 11 Introduction to Genetics
11.2 Applying Mendel’s Principles

3. Probability Math prediction as to chances of something happening
Chance of passing on a particular gene
Coin has two sides, a head and a tail, if you flip it, the chance of getting a head is ½.

4. If you flip a coin three times in a row, what is the probability that it will land heads up every time
Each flip is and independent event with a chance of ½
1/2 × 1/2 × 1/2 = 1/8.

5. F1 plant had one tall allele and one short allele (Tt)
1/2 of the gametes would carry the short allele (t).

6. The only way to produce a short (tt) plant is for two gametes carrying the t allele.

7. ½ x ½ = ¼. Chance of getting t allele is ½
Probability of being short (tt) is
½ x ½ = ¼.

8. For each of Mendel’s seven crosses, about ¾ of the plants showed the trait controlled by the dominant allele
¼ showed the recessive trait.

9. Probabilities predict the average outcome
The larger the sample the closer to the predicted.

10. Homozygous Heterozygous Two of the same alleles TT or tt
One of each version of the alleles, Hybrid
Tt.

11. Genotype Phenotype What the actual genes are, you can’t physically see
TT, Tt, or tt
Phenotype
What the trait looks like, what you can physically see
Tall or short.

12. Punnett Squares
Genetic cross to predict the genotype and phenotype using mathematical probability
Monohybrid
One trait cross
Dihybrid
Two trait cross.

13. How To Make a Punnett Square
Start with the Parents
Figure out the Gametes
Line them up
Fill in the Punnett Square
Figure out the Results.

14. Start with the Parents Bb and Bb.
Write the genotypes of the two parents
Bb and Bb.

15. Figure out the Gametes
Determine what alleles would be found in all of the possible gametes that each parent could produce.

16. Line them up
Draw a table with enough spaces for each pair of gametes from each parent
Enter the genotypes of the gametes produced by both parents on the top and left sides of the table.

17. Fill in the Punnett Square
Fill in the table by combining the gametes’ genotypes.

18. Figure out the Results
Determine the genotypes and phenotypes of each offspring
Calculate the percentage for each.

19. Homozygous round x Homozygous wrinkled

20. Homozygous round x Homozygous wrinkled

21. Homozygous round x Homozygous wrinkledRr

22. Homozygous round x Homozygous wrinkled

23. Independent Assortment
Genes for different traits can segregate independently during gamete formation
A past coin flip won’t influence a future coin flip.

24. Mendel crossed true-breeding round yellow peas with wrinkled green peas.

25. Round yellow peas had the genotype RRYY, which is homozygous dominant.

26. Wrinkled green peas had the genotype rryy, which is homozygous recessive.

27. All of the F1 offspring produced round yellow peas
F1 offspring was RrYy, heterozygous for both seed shape and seed color.

28. Mendel then crossed the F1 plants to produce F2 offspring.

29. Alleles for seed shape segregated independently of those for seed color
Mendel’s experimental results were very close to the 9:3:3:1 ratio that the Punnett square shown predicts.

30. Start with Parents

31. Figure out the Gametes

32. Line them Up

33. Fill in the Punnett Square

34. Figure out the Results

35. Thomas Hunt Morgan
Repeated Mendel’s work using fruit flies.