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?  Copy the following chart on a new sheet of paper:  Number down to 20. FIRST FIVE! HW! TRIAL #BABY’S GENOTYPE HETEROZYGOUS OR HOMOZYGOUS? BABY’S PHENOTYPE 1.

Objectives By the end of today, SWBAT…  Create and analyze Punnett Squares

Agenda  Catalyst Review  MAKING BABIES Lab (GASP!)  Punnett Squares  Guided Practice  Independent Practice  EQ

Remember…  GENotype = Combination of alleles inherited from the parents (the GENes)  PHenotype = PHysical expression of the trait

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)

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 recessive Genotype: Dd Phenotype: have dimples Heterozygous recessive Genotype: Dd Phenotype: have dimples

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 recessive Genotype: Bb Phenotype: brown eyes Heterozygous recessive Genotype: Bb Phenotype: brown eyes

Today, you are going to have 20 kids.  In 10 minutes, you will have 20 kids. Trait: Eye Color Alleles: B = Brown eyes, b = blue eyes TRIAL #BABY’S GENOTYPE HETEROZYGOUS OR HOMOZYGOUS? BABY’S PHENOTYPE 1.

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.

Answer the following questions: (6 minutes) 1.Which phenotype is dominant? Which is recessive? 2.Out of 20 trials, how many times did you get BB? Bb? bb? (Write it as a fraction. Convert to percent.) 3.Out of 20 trials, how many times did you get babies with brown eyes? blue eyes? (Write it as a fraction. Convert to percent.) 4.Based on these findings, what is the genotype and phenotype of the mother? The father? EXPLAIN how you know. Use complete sentences!

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

Probability…not EXACT  It is important to note that Punnett Squares only give probabilities for genotypes  They don’t give you the EXACT outcomes

Key Point #2  Parent generation = P1  Offspring = F1 P1 F1

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

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

Punnett Squares are COOL  Step 2, Part 2: Parents go on the top and on the left (keep each parents’ alleles together) BB B b

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

Just Punnett!  Step 4: Now, we analyze percent of each genotype. BB B b BB Bb How many homozygous dominant? 50% How many heterozygous? 50% How many homozygous recessive? 0%

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

Help me out here…  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.  Homozygous dominant  Homozygous recessive  Heterozygous 5) % of each phenotype.  Dominant phenotype  Recessive phenotype

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

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

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

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

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!

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