A Punnett square is a chart that helps

A Punnett square is a chart that helps us predict the probability that an offspring with a particular genotype and phenotype will be produced. Monohybrid Cross - ONE Trait we are interested in.

G P Genotype - actual set of alleles Example: PP, Pp, pp enotype henotype Homozygous dominant PP Heterozygous Pp Homozygous recessive pp Phenotype - physical appearance [i. e. what you SEE] Black coat Red flower Tall ; Short

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

Step 2: - Label one side of the box with the genotype of one parent. Example: R = tongue roller r = non-tongue roller R r Rr Parent 1 will be for this example

Step 3: - Label the other side of the box with the genotype of the other parent. R Example: R = tongue roller r = non-tongue roller Rr Parent 2 will be for this example R r r

Step 4: - Combine the letters in each box. Capital letter always goes first! Example: R = tongue roller r = non-tongue roller R R RR r 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 RR Rr rr The possible genotypes: 1 RR : 2 Rr : 1 rr 25% : 50% : 25%

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

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) ? ? ?

A cross between a black dog (Bb) and a brown dog (bb) Genotypes ? ? ? Phenotypes ? ? ?

YOU do… A cross between a yellow corn (Yy) and another yellow corn (Yy) (y = white corn) Genotypes ? ? ? Phenotypes ? ? ?

1. Genes 2. Allele 3. Dominant 4. Recessive 5. Heterozygous 6. Homozygous 7. Genotype 8. Phenotype 9. Punnet Square 10. Monohybrid cross