Question

Joan was born with six toes on each foot, a dominant trait called polydactyly. Two of her five siblings and her mother, but not her fathers, also have extra digits. What is Joan’s genotype for the number of digits character? Explain your answer. Use D and d symbolize the alleles for this character.

Short answer

Joan has the condition of polydactyly that is inherited from her mother. Joan has inherited the allele d from the father.D is the dominant allele, and d is the recessive allele.

Step-by-step solution

Description of gene

The gene is the heritable genetic material that is responsible for the unique characters of the organism. Gene mutation can result in the inheritance of certain new characters and is the cause of certain diseases.

Description of polydactyly

The condition due to the presence of extra fingers is known as polydactyly. The location of different fingers can occur in the thumb, middle finger, and little finger. Genetic mutations are the primary cause for this condition.

Inheritance of genotypic characters of Joan

The Dd is the genotype found in Joan. The dominant allele is D for this condition. The genotype such as DD or Dd is responsible for the state of polydactyly.

In the given question, Joan’s father does not have the polydactyly condition. So, the genotype of Joan’s father is dd. Joan has inherited the d allele from the father and D from the mother.