1. Review Genetics

2. Terms the letters and symbols the physical appearance or what you see a capital letter and a lower case letter 2 capital letters or 2 lower case letters the stronger trait the weaker trait Dominant Genotype Recessive Phenotype Hybrid Purebred

3. In Hamsters, the following conditions were found to be true: Purebred brown ______ Purebred white______ Purebred long______ Purebred short ______ Purebred straight ______ Purebred curly ______ Hybrid brown_______ Hybrid long_______ Hybrid straight ________ White ________ Short ________ Curly________ Brown hair was dominant over white hair Long hair was dominant over short hair Straight hair was dominant over curly hair

4. In petunia plants, the following conditions were found to be true: Can there be hybrid red flowers? _________ Can there be hybrid white flowers? _________ Can there be hybrid narrow leaves? _________ Can there be hybrid broad leaves? _________ Can there be hybrid short plants? _________ Red flowers were dominant over white flowers Tall plants were dominant over short plants Broad leaves were dominant over narrow leaves

5. In Hamsters, the following conditions were found to be true: Genotype of hybrid brown, hybrid long ___________ Genotype of short, white ___________ Genotype of purebred straight, hybrid long __________ Genotype of purebred curly, white ___________ Genotype of hybrid brown, purebred long___________ Brown hair was dominant over white hair Long hair was dominant over short hair Straight hair was dominant over curly hair

6. In petunia plants, the following conditions were found to be true: Phenotype of BB TT RR ________________________ Phenotype of Bb Tt Rr _________________________ Phenotype of bb TT Rr ________________________ Phenotype of bB tt rr _________________________ Phenotype of BB Tt rr _________________________ Red flowers were dominant over white flowers Tall plants were dominant over short plants Broad leaves were dominant over narrow leaves

7. Genetics and Prediction

8. Sunny with a chance of clouds What will the weather be tomorrow? Meteorologists use radar and other tools to predict the weather. But even if you know the forecast, you won’t actually know the weather until tomorrow. Genetics also have tools to predict probable offspring phenotypes.

9. Probability – predicting the likelihood of an event or outcome When you flip a coin, you can get either heads or tails – there are two possibilities. The probability of getting heads on any one flip is ½. If you flipped a coin ten times, you would expect heads to appear about 5 times or 50%.

10. Probability Can be measured as a fraction (1/2), a percentage (50%), or a ratio (1:1) How do you think probability can be used in science?

11. Scientists use a tool to make predictions about genetics, much like a meteorologist uses radar to make predictions about the weather. Punnett Square – a grid for organizing genetic information Predicts probability, not actual results Punnett squares can be used to make predictions about a cross between two organisms

12. How to make a Punnett square: 1. Make the grid – place the alleles of one parent along the top and the alleles of the other parent along the side. Both parents are heterozygous for yellow

13. How to make a Punnett square: 2. Fill in the grid – combine the parent alleles inside the boxes Y y YyYy

14. How to make a Punnett square: 3. Fill in the offspring – use the Law of Dominance to determine the phenotype of the offspring Y y YyYy YY Yy Yy yy

15. Genotypic ratio – ratio of possible letter combinations Y y YyYy YY Yy Yy yy How many YY? How many Yy? How many yy? Genotypic ratio = 1:2:1 How would you write the genotype in percentages?

16. Phenotypic ratio – ratio of possible appearances Y y YyYy YY Yy Yy yy How many yellows? How many greens? Phenotypic ratio = 3:1 How would you write the phenotype in fractions?

17. Keep in mind… Again, a Punnett square tells you the probability of the offspring genotypes, not the guaranteed outcome

18. What would be the results of a cross between a purebred round pea plant (RR) and a hybrid round pea plant (Rr)?

19. Types of crosses Monohybrid cross – studying only one trait at a time Yellow or Round Dihybrid cross – studying two traits at a time Yellow and Round

20. Dihybrid Crosses We want to cross parents who are both heterozygous for yellow round peas. YyRr x YyRr

21. Mendel’s Law of Independent Assortment states that alleles will sort into all possible outcomes Parent 1 = YyRr Parent 2 = YyRr YR Yr yR yr

22. Dihybrid Crosses 1. make the grid YyRr x YyRr YR Yr yR yr YR Yr yR yr

23. Dihybrid Crosses 2. Fill in the grid YR Yr yR yr YR Yr yR yr

24. Dihybrid Crosses 2. Fill in the offspring YR Yr yR yr YR Yr yR yr YYRR YYRr YyRR YyRr YYRr Yyrr YyRr Yyrr YyRR YyRr yyRR yyRr YyRr Yyrr yyRr yyrr What is the phenotypic ratio?