1. Wednesday – September 23, 2009 Objectives:  SWBAT create and analyze Punnett Squares. Catalyst:  What is the difference between a gene and an allele?  How do we represent dominant alleles? Recessive alleles?

2. Agenda  Catalyst Review  Making Babies Lab (GASP!)  Punnett Squares  Guided Practice  Independent Practice  Closing

3. Catalyst  A gene codes for a trait- eye color, ear lobes, dimples, etc.  An allele is a different version of a gene.  Ex: Brown vs. Blue eyes  Ex: Attached vs. Free hanging earlobes  Ex: Dimples vs. No dimples

4. Review Yesterday’s Vocab  Traits  Allele  Homozygous  Heterozygous  Dominant  Recessive Check your awesome notes!

5. Remember…  GENOTYPE = combination of alleles inherited from the parents (the genes)  PHENOTYPE = physical expression of the trait

6. Today, you are going to have 20 kids.  What?  Yes. In 15 minutes, you will have 20 kids.  You will need to find someone in the class to mate with.  We will demonstrate how this works.

7. Key Point #1  Punnett Squares are diagrams that are used to predict the genotypes of offspring.

8. Probability…not EXACT  It is important to note that Punnett Squares only give probabilities for genotypes  It doesn’t give you the EXACT outcomes  You will see when we start creating our Punnett Squares

9. Key Point #2  You can never know for sure what offspring will look like, you can only predict based on probability.

10. Key Point #3  We refer to the parent generation as P1 and the offspring of that generation as F1. P1 F1

11. Before we get started…  CAPTIALIZED letters are DOMINANT  lowercase letters are recessive Examples: B = brown hair (DOMINANT) b = blonde hair (recessive) Y = yellow (DOMINANT) y = green (recessive) P = purple (DOMINANT) p = white (recessive)

12. Before we get started… D = dimples d = no dimples D = dimples d = no dimples Homozygous dominant Genotype: DD Phenotype: have dimples Homozygous dominant Genotype: DD Phenotype: have dimples Homozygous recessive Genotype: dd Phenotype: no dimples Homozygous recessive Genotype: dd Phenotype: no dimples Heterozygous Genotype: Dd Phenotype: have dimples Heterozygous Genotype: Dd Phenotype: have dimples

13. Before we get started… B = brown eyes b = blue eyes B = brown eyes b = blue eyes Homozygous dominant Genotype: BB Phenotype: brown eyes Homozygous dominant Genotype: BB Phenotype: brown eyes Homozygous recessive Genotype: bb Phenotype: blue eyes Homozygous recessive Genotype: bb Phenotype: blue eyes Heterozygous Genotype: Bb Phenotype: brown eyes Heterozygous Genotype: Bb Phenotype: brown eyes

14. Big Pun-nett  Let’s make our own. First things first, draw yourself box and split it into 4 squares.

15. Punnett like its Hot  Now, read the problem and find the parents’ genotypes.  *Remember, use the first letter of the dominant trait. A homozygous dominant brown eyed male mates with a blue eyed female. BB bb

16. Punnett Squares are COOL  Parents go on the top and on the left (keep them together)  It doesn’t matter which parents goes on the top or the left BB b b b b

17. Punnett Square Dance  Now, bring em together.  The four boxes represent the possible kids. BB b b Bb

18. Just Punnett!  Now, we analyze.  Use quarters to figure out percentages. BB b b Bb How many homozygous dominant do we have? 0% How many heterozygous do we have? 100% How many homozygous recessive do we have? 0%

19. Punnett baby one more time  Lastly, figure out percentages by phenotypes. BB b b Bb What percentage will have brown eyes? 100% What percentage will have blue eyes? 0%

20. Let’s do one more on the board  A heterozygous dimpled male mates with a heterozygous dimpled female.

21. Whiteboard Guided Practice: Seed Shape  Solve the following Punnett Square.  A homozygous dominant round seeded plant is crossed with a heterozygous wrinkled plant.  Find the genotype and phenotype probabilities. R = round r = wrinkled Rr RR R R r R

22. Guided Practice: Earlobes  Solve the following Punnett Square  A male with attached earlobes mates with a heterozygous free hanging earlobe female.  Find the genotype and phenotype percentages. F = free f = attached ffFf ffFf f F f f

23. Oh, how we love Spongebob!  Your teacher will now pass out the GP & IP “Punnett Squares – Spongebob Style” worksheets  We’ll do some of them together…then you get to try the rest on your own!

24. Wrap Up  Punnett Squares are diagrams that are used to predict the genotypes of offspring.  You can never know for sure what offspring will look like, you can only predict based on probability.  We refer to the parent generation as P1 and the offspring of that generation as F1.

25. Exit Question Create a Punnett Square. Do a cross of two heterozyous parents for brown eyes. List the genotypes & phenotypes probabilities of both the P1 and F1 generations.