Who Punnet? Monohybrid Cross - ONE Trait we are interested in. A Punnett square is a chart that helps us predict the probability that an offspring with a particular genotype and phenotype will be produced. Students should have been introduced to Punnet Squares in 7th grade. Vocabulary that should have been introduced prior to using this presentation: genes, alleles, dominant, recessive, homozygous, heterozygous. Monohybrid Cross - ONE Trait we are interested in.

Academic Vocabulary Review G Genotype - actual set of alleles Example: PP, Pp, pp Homozygous dominant PP Heterozygous Pp Homozygous recessive pp enotype P henotype Phenotype - physical appearance [i.e. what you SEE] As a way to help students remember the difference b/n Genotype & Phenotype, have students draw an eye in the P of phenotype and remind them that it describes physical appearance of the possible offspring. Black coat Red flower Tall ; Short

Punnet Square Basics Step 1: - Draw a box and divide it into four quadrants [parts]

Punnet Square Basics R r Step 2: - Label one side of the box with the genotype of one parent. Example: R = tongue roller r = non-tongue roller Parent 1 will be Rr for this example R r Heredity basics to talk about during presentation: 1. Parents do not transmit traits but genes that control traits. [review] 2. For each trait an individual receives 2 alleles; one from Mom and one from Dad. [The presentation includes pictures of the gametes to indicate this]

Punnet Square Basics R r R r Step 3: - Label the other side of the box with the genotype of the other parent. R r Example: R = tongue roller r = non-tongue roller Parent 2 will be Rr for this example R r This may be a good time to review the terms: heterozygous and homozygous as a quick “Checking for Understanding”

Punnet Square Basics R r R r RR Rr rr Step 4: - Combine the letters in each box. Capital letter always goes first! Example: R = tongue roller r = non-tongue roller R r R r RR Rr rr

Analyzing a Punnet Square The letters represent alleles. The boxes represent the possible genotypes for the offspring of these two parents. R r R r RR Rr rr Remind students that the R = dominant allele and r = recessive allele. Make sure to use the terms: heterozygous, homozygous The possible genotypes: 1 RR : 2 Rr : 1 rr 25% : 50% : 25%

3 tongue rollers : 1 non-tongue roller P henotype The boxes also represent the possible Phenotypes for the offspring of these two parents. [how the possible offspring look] R r R r RR Rr rr Remind students that the R = dominant allele and r = recessive allele. The possible phenotypes: 3 tongue rollers : 1 non-tongue roller 75% : 25%

I do… Watch a Professional go to work!  A cross between a female with straight hair (SS) and a male with curly hair (ss) Genotype(s) ??? Phenotype(s) ??? Make sure all students are focused before beginning. Talk through it.

WE do… A cross between a black dog (Bb) and a brown dog (bb)   Genotypes ??? Phenotypes ??? As name suggests, do as a class. I usually will pretend I have amnesia and I need the help of the students to solve the problem. Ask students to describe why they are having you do what they tell you [they can refer back to the notes].

YOU do… A cross between a yellow corn (Yy) and another yellow corn (Yy) (y = white corn)   Genotypes ??? Phenotypes ??? Allow students to complete individually. Walk around and monitor student work – noting those who need help and those who “got it”. This serves as the Checking for Understanding

Academic Vocabulary Review Genes Allele Dominant Recessive Heterozygous 6. Homozygous 7. Genotype 8. Phenotype 9. Punnet Square 10. Monohybrid cross