Chapter 11, Problem 18A

Summary Introduction

To discuss:

The types of phenotypes possible if a phenotype were due to polygenic inheritance

Introduction:

Genetic disorders result from inheritance of traits which are either dominant or recessive. The basic patterns of human inheritance follow Mendel’s law of inheritance but there are some complex inheritance of traits that do not follow inheritance pattern described by Mendel. A characteristic that has more than one pair of possible trait is said to be a polygenic trait.

Answer to Problem 18A

A polygenic inheritance will be expressed in the form of a variety of phenotypes. There will be a continuous variation in phenotypes of polygenic inheritance.

Explanation of Solution

Some phenotypic traits are due to interaction of multiple pairs of genes. Such traits are called polygenic traits. Examples are traits like skin color, eye color, hair color, height and finger print pattern.

A number of intermediate phenotypes result due to multiple pairs of genes than only extreme phenotypes. Hence there would be variation in phenotypes. Because multiple genes are involved there would be a range of phenotypes. For example eye colors could be brown, blue, hazel or, green. There is a whole lot of colors in between too.