Create a gene and a corresponding allele on your whiteboard Gene: _____________ Allele: ________, _________ Alleles (variations of trait) -Purple, blue, white -curly, straight, wavy -Short, tall Gene (trait) -Flower Color -Hair type -Plant Height

 Phenotype  Physical appearance terms  ex. Tall, short, brown hair etc.  Genotype  Genes in cell, written with letters that represent the genes (ex: “T” for tall, or “t” for short)

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

1. RR= 2. Ll= 3. Yy 4. Ee

1. A fish is homozygous recessive for fin color 2. A cat is heterozygous for tail length. 3. A turtle is homozygous dominant for shell color. 4. A polar bear is homozygous recessive for claw length.

Sample Problem T represents the gene for TALL in pea plants t represents the gene for short in pea plants So: TT & Tt both result in a TALL plant, because T is dominant over t. t is recessive. What will tt result in? Remember there are two genes for every trait!

 Write the 3 possible genotypes and phenotypes for the following:  Green eyes are dominant to blue eyes  (use the first letter of the dominant trait)  GG=  Gg=  gg=

 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)  CC=  Cc=

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 TTtt

TTtt Each gene (allele) separates from the other so that the offspring get only one gene from each parent for a given trait. TTtt TT x t t

 Predict the offspring if a tall plant (TT) is crossed (mates) with a short plant (tt) TT x tt

TtTtTt t The genes from one parent go here. The genes from the other parent go here.

TT tTtTtTt t

TT t t If a box receives a capital letter and a lower- cased letter we write the capitol letter first

Possible offspring Genotype =

Possible offspring Genotype = Tt.

What percent of offspring will have the following genotypes: TT= Tt= tt=

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

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

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

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=

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%

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 _____________

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.

Black rabbits are dominant to brown. Two heterozygous rabbits have offspring. Predict what percentage of their offspring will be brown?

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

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

Tt TTTTt t tt

 Determine the genotype percentages and write on whiteboard  TT=  Tt=

Tt TTTTt t tt Genotype percentage : TT – 25%

Tt TTTTt t tt Genotype percentage: TT – 25%, Tt – 50%

Tt TTTTt t tt Genotype percentage: TT – 25%, Tt – 50%, tt – 25%

 Determine the Phenotype percentages and write on whiteboard  Tall=  Short=

Tt TTTTt t tt Genotype percentage: TT – 25%, Tt – 50%, tt – 25% Phenotype percentage: Tall – 75%

Tt TTTTt t tt Genotype percentage: TT – 25%, Tt – 50%, tt – 25% Phenotype percentage: Tall – 75%, short – 25%

Round seeds are dominant to wrinkled seeds.  Rr x rr What percentage of the offspring will be round? _______________

 Classwork: Punnett Packet Pages 1-?  Homework: Punnett Packet Pages ?-? (due tomorrow)