PUNNETT PRACTICE PREDICTING INHERITANCE Punnett Squares diagram that

PUNNETT PRACTICE

PREDICTING INHERITANCE • Punnett Squares: diagram that determines the probable distribution of inherited traits in the offspring. • UPPERCASE letters are used to represent dominant genes (traits). • lowercase letters are used to represent recessive genes (traits).

HOMOZYGOUS VS. HETEROZYGOUS Homozygous: Both alleles are the same. Either both capitols (dominant) or both lowercased (recessive) Example: • BB (homozygous dominant) • bb (homozygous recessive)

HOMOZYGOUS VS. HETEROZYGOUS Homozygous: Both alleles are the same. Either both capitols (dominant) or both lowercased (recessive) Example: • BB (homozygous dominant) • bb (homozygous recessive) Heterozygous: Both alleles are different. One capital letter and one lower-cased letter. Example: Bb

WHITE BOARD PRACTICE

WRITE HET OR HOM FOR THE FOLLOWING GENOTYPES 1. RR= 2. Ll= 3. gg= 4. Ee =

WRITE THE GENOTYPES FOR THE FOLLOWING ORGANISMS. USE THE LETTER R 1. A fish is homozygous recessive for fin color 2. A cat is heterozygous for tail length.

WRITE THE GENOTYPES FOR THE FOLLOWING ORGANISMS. USE THE LETTER R 1. A turtle is homozygous dominant for shell color. 2. A polar bear is homozygous recessive for claw length.

WHITE BOARD PRACTICE

SAMPLE PROBLEMS Write the 3 possible genotypes for eye color. Green eyes are dominant to blue eyes (use the first letter of the dominant trait) 1. ____ 2. ____ 3. ____

SAMPLE PROBLEMS Write the 3 phenotypes for eye color. Green eyes are dominant to blue eyes GG= Gg= gg=

SAMPLE PROBLEMS Write the 3 possible genotypes and phenotypes for the following: Curled toes are dominant to straight toes (use the first letter of the dominant trait) 1. ____= ____ 2. ____= ____ 3. ____= ____

PRACTICE PROBLEM #1 Let’s cross a homozygous tall plant (TT) with a short plant (tt). Each plant will give only one of its’ two genes to the offspring. TT x tt T T t t

MENDELS’ LAW OF SEGREGATION Each gene (allele) separates from the other so that the offspring get only one gene from each parent for a given trait. TT x t t T T tt tt Mendel’s Law of Segregation

CROSS TT X tt BY USING A PUNNETT SQUARE Tt Tt The genes from one parent go here. The genes from the other parent go here. Tt t

CROSS TT X tt BY USING A PUNNETT SQUARE T T t Tt Tt

CROSS TT X tt BY USING A PUNNETT SQUARE If a box receives a capital letter and a lower -cased letter we write the capitol letter first T T t Tt Tt

INTERPRETING THE RESULTS Possible offspring Genotype =

INTERPRETING THE RESULTS Possible offspring Genotype = Tt. What percent of offspring will have the following genotypes: TT= Tt= tt=

INTERPRETING THE RESULTS Possible offspring Genotype = Tt. What percent of offspring will have the following genotypes: TT= Tt= tt=

INTERPRETING THE RESULTS Possible offspring Genotype = Tt. What percent of offspring will have the following genotypes: TT= 0% Tt= 100% tt= 0% Possible offspring phenotype =

INTERPRETING THE RESULTS Possible offspring Genotype = Tt. What percent of offspring will have the following genotypes: TT= 0% Tt= 100% tt= 0% Possible offspring phenotype = tall. What percent of offspring will have the following phenotypes: Tall= Short=

INTERPRETING THE RESULTS Possible offspring Genotype = Tt. What percent of offspring will have the following genotypes: TT= 0% Tt= 100% tt= 0% Possible offspring phenotype = tall. What percent of offspring will have the following phenotypes: Tall= 100% Short= 0%

PRACTICE PROBLEM #2 Black rabbits are dominant to brown. Two heterozygous rabbits have offspring. Predict what percentage of their offspring will be brown.

PRACTICE PROBLEM Black rabbits are dominant to brown. Two heterozygous rabbits have offspring. Predict what percentage of their offspring will be brown. Step 1: Determine the genotype of parents. Always use the first letter of the dominant trait. ______x _______

Step 2: Set up a Punnett Square Step 3: Complete Punnett Square Step 4: Predict offspring phenotype

PRACTICE PROBLEM Black rabbits are dominant to brown. Two heterozygous rabbits have offspring. Predict what percentage of their offspring will be brown? % Black= _____ % Brown= _____

WHITE BOARD PRACTICE

Tall plants are dominant to short. Cross two heterozygous pea plants. 1. Determine parent’s genotype and write on whiteboard

Set up a punnett square and fill it in. Hold up whiteboard

PUNNETT SQUARES T t T TT Tt tt

Determine the genotype percentages and write on whiteboard 1. TT= 2. Tt= 3. Tt=

Determine the Phenotype percentages and write on whiteboard • Tall= • Short=

ONE MORE WHITEBOARD PRACTICE Round seeds are dominant to wrinkled seeds. Rr x rr What percentage of the offspring will be round? ________