How to set up Punnet Squares. Punnet Square Vocabulary Genotype - An organisms genetic makeup or allele combination; for one specific trait we use two

How to set up Punnet SquaresHow to set up Punnet Squares

Punnet Square VocabularyPunnet Square Vocabulary Genotype - Genotype - An organisms An organisms

genetic makeup or allele genetic makeup or allele combination; for one combination; for one specific trait we use specific trait we use two two lettersletters to represent the to represent the genotype. A genotype. A capitalcapital letter letter represents the represents the dominantdominant form of a gene (allele), form of a gene (allele), and a and a lowercaselowercase letter is letter is the abbreviation for the the abbreviation for the recessiverecessive form of the form of the gene (allele).gene (allele).

Ex. RR, Rr, rrEx. RR, Rr, rr

Punnet Square VocabularyPunnet Square Vocabulary

Phenotype - An Phenotype - An organisms appearance organisms appearance or or visiblevisible traits. traits.

Ex. Color, shapeEx. Color, shape


Homozygous - Both Homozygous - Both Genes (alleles) are the Genes (alleles) are the SAMESAME as each other as each other

Ex. Ex. RRRR, , rrrr


Heterozygous - Both Heterozygous - Both Genes (alleles) are Genes (alleles) are DIFFERENTDIFFERENT from from each othereach other

Ex. Ex. RrRr


Homozygous Homozygous DOMINANT - Both DOMINANT - Both Genes (alleles) are Genes (alleles) are DOMINANT DOMINANT (Capitol (Capitol letters) AND ARE THE letters) AND ARE THE SAMESAME AS EACH AS EACH OTHEROTHER

Ex. Ex. CCCC


Homozygous Homozygous RECESSIVE - Both RECESSIVE - Both Genes (alleles) are Genes (alleles) are RECESSIVE RECESSIVE (lower (lower case letters) AND ARE case letters) AND ARE THE THE SAMESAME AS EACH AS EACH OTHEROTHER

Ex. Ex. cccc


Heterozygous - Both Heterozygous - Both Genes (alleles) are Genes (alleles) are DIFFERENTDIFFERENT from from each othereach other

Ex. Ex. CcCc (one Capitol (one Capitol letter one and lower letter one and lower case letter)case letter)

ProblemProblem

Cross a short person Cross a short person with one that is with one that is heterozygous for heterozygous for tallnesstallness??

Examining the problem…Examining the problem…

Here, you have to use your understanding of Here, you have to use your understanding of the vocabulary to figure out what letters to use the vocabulary to figure out what letters to use in the genotypes of the parents. Where "T" = in the genotypes of the parents. Where "T" = tall Dominant, & "t" = short recessive. One tall Dominant, & "t" = short recessive. One parent is Heterozygous which always means parent is Heterozygous which always means one of each letter, so we'd use "one of each letter, so we'd use "TtTt" The only " The only way for a person to be short is when it has 2 way for a person to be short is when it has 2 lowercase "t's", so that parent is “lowercase "t's", so that parent is “tttt".".

1. determine the genotypes of the 1. determine the genotypes of the parent organismsparent organisms

Parent # 1Parent # 1– Short personShort person

Homozygous RecessiveHomozygous Recessive

Parent # 2Parent # 2– Tall personTall person

HeterozygousHeterozygous

t tt t

T tT t

2. write down your "cross" 2. write down your "cross" (mating)(mating)

So the cross ends-up written like this…So the cross ends-up written like this…

T tT t x x t tt t

3. draw a p-square3. draw a p-square

4. "split" the letters of the genotype for each 4. "split" the letters of the genotype for each parent & put them "outside" the p-squareparent & put them "outside" the p-square

Take the Take the genotype letters genotype letters of one parent, of one parent, split them and split them and put them on the put them on the left, outside the left, outside the rows of the p-rows of the p-square.square.

4. "split" the letters of the genotype for each 4. "split" the letters of the genotype for each parent & put them "outside" the p-squareparent & put them "outside" the p-square

Now take the two Now take the two letters of the letters of the second parent's second parent's genotype, split genotype, split them up, and them up, and place them place them above each of above each of the two columns the two columns of the p-square.of the p-square.

5. determine the possible genotypes of 5. determine the possible genotypes of the offspring by filling in the p-squarethe offspring by filling in the p-square

I kind of gave this away I kind of gave this away already, but to already, but to "determine the "determine the genotypes of the genotypes of the offspring" all we have to offspring" all we have to do is fill-in the boxes of do is fill-in the boxes of the p-square. Again we the p-square. Again we do this be taking a letter do this be taking a letter from the left & matching from the left & matching it with a letter from the it with a letter from the top. Like so:top. Like so:

Fill in the rest of the boxes…Fill in the rest of the boxes…



6. summarize results (genotypes 6. summarize results (genotypes & phenotypes of offspring)& phenotypes of offspring)

Parents Parents ("P" Generation)("P" Generation)

Offspring Offspring ("F1" Generation)("F1" Generation)

GenotypesGenotypes

TtTt x x tttt

PhenotypesPhenotypes

TallTall x x shortshort

GenotypesGenotypes

50% (2/4) 50% (2/4) TtTt 50% (2/4) 50% (2/4) tttt

Phenotypes:Phenotypes:

50% 50% talltall 50% 50% shortshort

Punnet Square StepsPunnet Square Steps 1. determine the genotypes of the parent1. determine the genotypes of the parent

organismsorganisms 2. write down your "cross" (mating)2. write down your "cross" (mating) 3. draw a p-square3. draw a p-square 4. "split" the letters of the genotype for each 4. "split" the letters of the genotype for each parent & put them "outside" the p-squareparent & put them "outside" the p-square 5. determine the possible genotypes of the 5. determine the possible genotypes of the offspring by filling in the p-squareoffspring by filling in the p-square 6. summarize results (genotypes & 6. summarize results (genotypes & phenotypes of offspring)phenotypes of offspring)

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How to set up Punnet Squares. Punnet Square Vocabulary Genotype - An organisms genetic makeup or allele combination; for one specific trait we use two