Chapter 11, Problem 7A

Summary Introduction

To describe:

The inheritance pattern of the genetic disorder that the given tree frog would have

Introduction:

Genetic disorders result from inheritance of traits which are either dominant or recessive. Most disorders are due to recessive alleles but some disorders like Huntington’s disease is due to dominant allele. Those who do not have the disorder are homozygous recessive for the trait.

Answer to Problem 7A

The frog in the given picture is dwarf. It has a small body and limbs are also short. Hence it is suffering from a rare genetic disorder called achondroplasia which is a common form of dwarfism. This is a dominant gene disorder so it will be expressed in homozygous as well as in heterozygous genotypes. It will not be expressed in homozygous recessive condition.

Explanation of Solution

Achondroplasia is a dominant genetic disorder, a form of dwarfism in humans. As can be seen in the given picture, the tree frog has a small body and short limbs. So it is suffering from some kind of dwarfism. Since it is assumed that all animals suffer from same genetic disorders that humans have, it can be concluded that the tree frog is suffering from achondroplasia. In this disorder a gene that affects bone growth is abnormal.

In a dominant genetic condition, the genotype will be seen in phenotype. It will be expressed even if one allele is present in an individual; that is in heterozygous as well as in homozygous condition. It is quite interesting that 75% of individuals with achondroplasia are born to parents with average height. This may be due to mutations or some genetic change.