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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
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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)
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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).
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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
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1. RR= 2. Ll= 3. Yy 4. Ee
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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.
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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!
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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=
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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=
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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
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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
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Predict the offspring if a tall plant (TT) is crossed (mates) with a short plant (tt) TT x tt
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TtTtTt t The genes from one parent go here. The genes from the other parent go here.
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TT tTtTtTt t
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TT t t If a box receives a capital letter and a lower- cased letter we write the capitol letter first
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Possible offspring Genotype =
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Possible offspring Genotype = Tt.
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What percent of offspring will have the following genotypes: TT= Tt= tt=
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Possible offspring Genotype = Tt. What percent of offspring will have the following genotypes: TT= 0% Tt= 100% tt= 0%
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Possible offspring Genotype = Tt. What percent of offspring will have the following genotypes: TT= 0% Tt= 100% tt= 0% Possible offspring phenotype =
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Possible offspring Genotype = Tt. What percent of offspring will have the following genotypes: TT= 0% Tt= 100% tt= 0% Possible offspring phenotype = tall.
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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=
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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%
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Black rabbits are dominant to brown. Two heterozygous rabbits have offspring. Predict what percentage of their offspring will be brown.
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Step 1: Determine the genotype of parents. Always use the first letter of the dominant trait. ____________x _____________
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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 _____________
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Step 2: Set up a Punnett Square
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Step 3: Complete Punnett Square
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Step 4: Predict offspring phenotype.
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Black rabbits are dominant to brown. Two heterozygous rabbits have offspring. Predict what percentage of their offspring will be brown?
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Tall plants are dominant to short. Cross two heterozygous pea plants. 1. Determine parent’s genotype and write on whiteboard Your Turn!!
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Set up a punnett square and fill it in. Hold up whiteboard
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Tt TTTTt t tt
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Determine the genotype percentages and write on whiteboard TT= Tt=
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Tt TTTTt t tt Genotype percentage : TT – 25%
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Tt TTTTt t tt Genotype percentage: TT – 25%, Tt – 50%
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Tt TTTTt t tt Genotype percentage: TT – 25%, Tt – 50%, tt – 25%
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Determine the Phenotype percentages and write on whiteboard Tall= Short=
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Tt TTTTt t tt Genotype percentage: TT – 25%, Tt – 50%, tt – 25% Phenotype percentage: Tall – 75%
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Tt TTTTt t tt Genotype percentage: TT – 25%, Tt – 50%, tt – 25% Phenotype percentage: Tall – 75%, short – 25%
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Round seeds are dominant to wrinkled seeds. Rr x rr What percentage of the offspring will be round? _______________
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Classwork: Punnett Packet Pages 1-? Homework: Punnett Packet Pages ?-? (due tomorrow)
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