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Big Punnett-ing

Big Punnett-ing. Catalyst: Six fingers (S) is dominant over five fingers (s). What is the phenotype of a person who is heterozygous ? How did I decide to use the letters “S” and “s” to represent dominant and recessive?. Write in complete sentences! Don’t talk during the Catalyst!.

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Big Punnett-ing

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  1. Big Punnett-ing • Catalyst: • Six fingers (S) is dominant over five fingers (s). What is the phenotype of a person who is heterozygous? • How did I decide to use the letters “S” and “s” to represent dominant and recessive? Write in complete sentences! Don’t talk during the Catalyst!

  2. Objectives By the end of today, SWBAT… • Create and analyze Punnett Squares

  3. Agenda • Catalyst Review • MAKING BABIES Lab (GASP!) • Punnett Squares • Guided Practice • Independent Practice • Closing

  4. Remember… • GENotype = Combination of alleles inherited from the parents (theGENes) • PHenotype = PHysicalexpression of the trait

  5. Before we get started, remember… • 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)

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

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

  8. Today, you are going to have 20 kids. • Oh, Lawd! • In 15 minutes, you will have 20 kids. • You will need to find someone in the class to “mate” with.

  9. Making Babies Lab! • Each partner has one lunch bag. Each lunch bag represents the genes that person gives to their child. • Inside the bag are the two alleles for ONE gene. • To make a baby… • WITHOUT looking into the bag, reach in and grab a letter (your partner will do the same). • Record the genotype in Data Table 1. • YOU HAVE JUST MADE A BABY.

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

  11. Probability…not EXACT • It is important to note that Punnett Squares only give probabilitiesfor genotypes • They don’t give you the EXACT outcomes

  12. Key Point #2 • We refer to the parent generation as P1 and the offspring of that generation as F1. P1 F1

  13. Big Pun-nett • Let’s make our own. • Step 1: Draw yourself a box and split it into 4 squares.

  14. Punnett like its Hot • Step 2, Part 1: Read the problem and find the parents’ genotypes. • Use the first letter of the dominant trait. A homozygous dominant brown eyed male mates with a heterozygous female. BB Bb

  15. Punnett Squares are COOL • Step 2, Part 2: Parents go on the top and on the left (keep each parents’ alleles together) • It doesn’t matter which parents goes on the top or the left B B B b

  16. Punnett Square Dance • Step 3: Now, bring them together. • The four boxes represent the possible kids. B B BB BB B b Bb Bb

  17. Just Punnett! • Step 4: Now, we analyze percent of each genotype. • Use quarters to figure out percentages. • How many homozygousdominant do we have? 50% • How many heterozygous do we have? 50% • How many homozygous recessive do we have? 0% B B BB BB B b Bb Bb

  18. Punnett baby one more time • Step 5: Figure out percentages by phenotypes. • What percentage will have brown eyes? 100% • What percentage will have blue eyes? 0% B B BB BB B b Bb Bb

  19. A heterozygous dimpled male mates with a heterozygous dimpled female. 1) Draw your box. 2) Find parents’ genotypes. Label box. 3) Bring them together. 4) % of each genotype. 5) % of each phenotype. Let’s mate one more time…

  20. 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 R RR RR R Rr Rr r R = round r = wrinkled

  21. GENOTYPES Homozygous Dominant (RR) Homozygous Recessive (rr) Heterozygous (Rr) PHENOTYPES Round seed Wrinkled seed A homozygous dominant round seeded plant is crossed with a heterozygous wrinkled plant. R R RR RR R Rr Rr r R = round r = wrinkled

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

  23. GENOTYPES Homozygous Dominant (FF) Homozygous Recessive (ff) Heterozygous (Ff) PHENOTYPES Free earlobes Attached earlobes A male with attached earlobes mates with a heterozygous female. F f Ff ff f Ff ff f F = free f = attached

  24. Oh, how we love Spongebob! • Punnett Squares – Spongebob Style worksheet • We’ll do some of them together… then you get to try the rest on your own!

  25. Exit Question D = dimples, d = no dimples Create a Punnett Square for two parents who are heterozygous. List the percent of children that will have each genotypeAND each phenotype.

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