Lesson: Sex and Autosomal Linkage Biology

In this lesson, we will learn how to identify sex-linked traits and explain how autosomal linkage impacts inheritance of genes.

Lesson Plan

Students will be able to

give examples of sex-linked traits including color blindness and hemophilia,
interpret genetic diagrams displaying inheritance of these traits,
distinguish between sex-linked, sex-influenced, and sex-limited traits,
describe and explain autosomal linkage,
analyze genetic diagrams that demonstrate the sex-linked inheritance (e.g., inheritance of eye color in Drosophila, as shown by Thomas Morgan).

Lesson Explainer

Lesson Worksheet

Q1:

The gene for milk production in humans is located on an autosome. However, the gene is only expressed in females and it is turned off in males. What is this an example of?

Q2:

Duchenne muscular dystrophy (DMD) is an X-linked recessive condition in humans that causes muscle weakness and wasting.

The allele that correctly produces the dystrophin protein (D) is dominant to the allele that causes DMD (d).

A female with the genotype X^DX^d reproduces with a male with the genotype X^DY.

What is the probability, in percent, that the offspring will be a male with the disease?

Q3:

Autosomes are chromosomes that do not determine the sex of a human. What is meant by autosomal linkage?