Module 6 Mendelian Genetics
Lesson 3.6.3
Lesson 3—Multiple Alleles and Incomplete Dominance Crosses
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Get Focused
Life is rarely black and white or, in the case of flowers, red and white! Instead, many physical characteristics observed in plants, or in people, have a variety of phenotypes; certainly more than the two that can be accounted for by Mendel’s dominant and recessive inheritance pattern. While our study of genetics could very quickly become more complex, there are two ways we can add a bit of variety and still use Mendel’s simple laws to explain them. Staying with monohybrid crosses, we will consider multiple alleles and incomplete dominance. By examining these two new inheritance patterns, you will be able to explain a little bit more of the variety you see around you.
In this lesson, you will explore traits that do not follow Mendel’s patterns of simple dominance, but can still be explained by his laws. You will also come to understand how genes can have more than two alternate forms.
In this lesson, the following focusing questions will be examined:
- What happens when one allele is not completely dominant over another?
- How does having more than two alleles for a gene affect the possible phenotypes for a trait?
This lesson will take approximately 80 minutes to complete.
Module 6: Lesson 3 Assignment
You will complete a lab on chicken genetics for assessment. You will then complete the online assignment for this lesson.
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.
Here is a tutorial video for this lesson that you can watch if it suits your learning style. Bio30 tut#3.6.3 Exceptions to Mendel