INHERITANCE PROBLEMS

 

Make punnet squares for the 4 following inheritance problems

 

Recommended procedures:

            1. Always use the letter A – big “A” for dominant, small “a” for recessive

            2. Before you start each problem write down the big “A” and the small “a” and

    indicate which one has the disease (or in problem #2 dwarfism)


 

1.         The gene for Huntington’s chorea (a disease) is dominant.  A mating occurs between someone who is heterozygous for the disease and a normal person (one without the disease). 

 

What are the chances of their offspring having the disease? 

Write the genotypic and phenotypic ratios.

 

 

 

 

 

 

 

 

 

 

 

 

2.         The gene for achondroplasia (dwarfism) is dominant.  A mating occurs between two individuals who are heterozygous for the achondroplasia gene.

 

            What are the chances of the offspring being achondroplasia dwarfs

            Write the genotypic and phenotypic ratios

 

 

 

 

 

 

 

 

 

 

 

 

 

3.         The gene for cystic fibrosis (a disease) is recessive.  A mating occurs between two heterozygous individuals.

 

            What are the chances of the offspring having the disease

            What are the chances of the offspring being phenotypically normal

            What are the chances of the offspring being homozygous normal

            Write the genotypic and phenotypic ratios

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.         The gene for phenylketonuria (a disease) is recessive.  A mating occurs between a

            heterozygous male and homozygous normal female.

 

What percentage of offspring will have a normal phenotype