Question

mendelian genetics worksheet name hour
fill in the punnett squares for each cross given to determine the phenotype and genotype ratios of the offspring
crosses with one homozygous dominant parent:
aa x aa
aa x aa
aa x aa
offspring genotypes:
aa__ aa aa__
aa__ aa aa__
aa__ aa aa__
offspring phenotypes:
dominant____
dominant____
dominant____
recessive____
recessive____
recessive____
crosses with one heterozygous parent:
aa x aa
aa x aa
aa x aa
offspring genotypes:
aa__ aa aa__
aa__ aa aa__
aa__ aa aa__
offspring phenotypes:
dominant____
dominant____
dominant____
recessive____
recessive____
recessive____
crosses with one homozygous recessive parent:
aa x aa
aa x aa
aa x aa
offspring genotypes:
aa__ aa aa__
aa__ aa aa__
aa__ aa aa__
offspring phenotypes:
dominant____
dominant____
dominant____
recessive____
recessive____
recessive____

Explanation:

Step1: Analyze \(AA\times AA\)

• Genotype:
• When \(AA\times AA\), using the Punnett - square method (\(A\) from one parent and \(A\) from the other parent in all four boxes of the Punnett square).
• The possible genotypes of the offspring are \(AA\). The number of \(AA\) is \(4\), \(Aa = 0\), \(aa=0\).
• Phenotype:
• Since \(A\) is dominant, all offspring (\(4\) out of \(4\)) show the dominant phenotype. The number of recessive phenotypes (\(aa\) - related) is \(0\).

Step2: Analyze \(AA\times Aa\)

• Genotype:
• The Punnett - square has two \(AA\) (from \(A\times A\) and \(A\times A\)) and two \(Aa\) (from \(A\times a\) and \(A\times a\)). So \(AA = 2\), \(Aa=2\), \(aa = 0\).
• Phenotype:
• Both \(AA\) and \(Aa\) show the dominant phenotype. So the number of dominant phenotypes is \(4\) and recessive phenotypes is \(0\).

Step3: Analyze \(AA\times aa\)

• Genotype:
• All offspring have the genotype \(Aa\) (from \(A\times a\) in each box of the Punnett square). So \(AA = 0\), \(Aa=4\), \(aa = 0\).
• Phenotype:
• \(Aa\) shows the dominant phenotype. So the number of dominant phenotypes is \(4\) and recessive phenotypes is \(0\).

Step4: Analyze \(Aa\times AA\)

• Genotype:
• Similar to \(AA\times Aa\), we have \(AA = 2\), \(Aa=2\), \(aa = 0\).
• Phenotype:
• Both \(AA\) and \(Aa\) show the dominant phenotype. So the number of dominant phenotypes is \(4\) and recessive phenotypes is \(0\).

Step5: Analyze \(Aa\times Aa\)

• Genotype:
• Using the Punnett - square (\(A\times A\), \(A\times a\), \(a\times A\), \(a\times a\)), we get \(AA = 1\), \(Aa = 2\), \(aa=1\).
• Phenotype:
• \(AA\) and \(Aa\) show the dominant phenotype (\(3\) in total), and \(aa\) shows the recessive phenotype (\(1\)).

Step6: Analyze \(Aa\times aa\)

• Genotype:
• From the Punnett - square (\(A\times a\) and \(a\times a\) in two boxes each), we have \(AA = 0\), \(Aa=2\), \(aa = 2\).
• Phenotype:
• \(Aa\) shows the dominant phenotype (\(2\)) and \(aa\) shows the recessive phenotype (\(2\)).

Step7: Analyze \(aa\times AA\)

• Genotype:
• All offspring have \(Aa\) (from \(a\times A\) in each box). So \(AA = 0\), \(Aa=4\), \(aa = 0\).
• Phenotype:
• \(Aa\) shows the dominant phenotype. So the number of dominant phenotypes is \(4\) and recessive phenotypes is \(0\).

Step8: Analyze \(aa\times Aa\)

• Genotype:
• Similar to \(Aa\times aa\), \(AA = 0\), \(Aa=2\), \(aa = 2\).
• Phenotype:
• \(Aa\) shows the dominant phenotype (\(2\)) and \(aa\) shows the recessive phenotype (\(2\)).

Step9: Analyze \(aa\times aa\)

• Genotype:
• All offspring have \(aa\) (from \(a\times a\) in each box). So \(AA = 0\), \(Aa=0\), \(aa = 4\).
• Phenotype:
• \(aa\) shows the recessive phenotype. So the number of dominant phenotypes is \(0\) and recessive phenotypes is \(4\).

Answer:

• \(AA\times AA\):
• Genotypes: \(AA = 4\), \(Aa=0\), \(aa = 0\)
• Phenotypes: Dominant \(= 4\), Recessive \(=0\)
• \(AA\times Aa\):
• Genotypes: \(AA = 2\), \(Aa=2\), \(aa = 0\)
• Phenotypes: Dominant \(= 4\), Recessive \(=0\)
• \(AA\times aa\):
• Genotypes: \(AA = 0\), \(Aa=4\), \(aa = 0\)
• Phenotypes: Dominant \(= 4\), Recessive \(=0\)
• \(Aa\times AA\):
• Genotypes: \(AA = 2\), \(Aa=2\), \(aa = 0\)
• Phenotypes: Dominant \(= 4\), Recessive \(=0\)
• \(Aa\times Aa\):
• Genotypes: \(AA = 1\), \(Aa=2\), \(aa = 1\)
• Phenotypes: Dominant \(= 3\), Recessive \(=1\)
• \(Aa\times aa\):
• Genotypes: \(AA = 0\), \(Aa=2\), \(aa = 2\)
• Phenotypes: Dominant \(= 2\), Recessive \(=2\)
• \(aa\times AA\):
• Genotypes: \(AA = 0\), \(Aa=4\), \(aa = 0\)
• Phenotypes: Dominant \(= 4\), Recessive \(=0\)
• \(aa\times Aa\):
• Genotypes: \(AA = 0\), \(Aa=2\), \(aa = 2\)
• Phenotypes: Dominant \(= 2\), Recessive \(=2\)
• \(aa\times aa\):
• Genotypes: \(AA = 0\), \(Aa=0\), \(aa = 4\)
• Phenotypes: Dominant \(= 0\), Recessive \(=4\)