Module 6 Mendelian Genetics

Lesson 8—Polygenetic Traits

Get Focused

On the top of a chicken’s head is a fleshy growth known as its comb. There are four possible phenotypes for chicken combs; rose, pea, walnut, and single. Up until this lesson, if you were presented with this information you would need to suspect multiple alleles were responsible for this trait. However, a walnut chicken can be crossed with another walnut chicken and their offspring can display all four of the possible phenotypes. That would just not be possible with any amount of alleles if this trait was explained by a single gene. This type of inheritance could only be possible if more than one gene was acting to create the same trait!

In this lesson, you will study traits that are controlled by many genes. You will recognize inheritance patterns that show gradual changes in phenotypes, and you will understand that the expression of one gene can turn the expression of another on or off.

In this lesson, the following focusing question will be examined:

• How might multiple genes combine to form a single trait?

This lesson will take approximately 60 minutes to complete.

Module 6: Lesson 8 Assignment

Once you have completed all of the learning activities for this lesson, complete the online assignment.

Bio30 3.6.8 online assignment

The other questions and activities in this lesson are not marked by the teacher; however, you should still attempt all of the work offered here. They are designed to help you review important information and build key concepts that may be applied in future lessons.