GN: Pedigree Lesson

What's Your Pedigree?

Pick a trait to trace throughout your family, such as eye color or hair color. Collect information about the members of your family and see how many generations you can trace.

How would you represent that information?

Would you write a story or would a picture be better?

When scientists study traits passed through generations, they create a pedigree.

Pedigrees do not just refer to animals, such as horses and dogs.

As you make your way through the microlesson, you will learn how pedigrees relate to humans and how they are used to study traits throughout generations.

What is a Pedigree?

A pedigree is a graphic method of illustrating the inheritance of genetic traits within several generations of families. Geneticists, genetic counselors, and animal breeders all use pedigrees to answer questions about inheritance using these tools.

Examine the pedigree below. Pay special attention to the symbols that are used to construct it. Think about what a pedigree might look like for your family. Sketch one out if you can.

• Males/females are represented by different shapes
• Mating is represented by horizontal lines between shapes
• Offspring are represented by vertical lines extending down from a mating
• Children are listed in birth order from left to right
• An affected individual is one who carries or expresses the trait of interest

What's a Carrier?

In addition to these standard symbols, some pedigrees will also include a half-colored symbol to indicate that an individual has one dominant and one recessive allele for the trait. This individual is called a carrier.

The Queen's Pedigree

Examine the pedigree of Queen Victoria's bloodline below. Can you see how the disease was transmitted from mothers to affected (hemophiliac) sons, and by way of daughters who were carriers? A key is located below the pedigree to help you.

Pedigree Challenge and Before You Go

Practice Time! Use the knowledge you learned from the lesson to complete the practice activities below.

Before You Go - You Need To Know

The following key points are from the explore section of the lesson. You must know the following information before moving to the next lesson. This is just a summary of the key points.

1. What is a pedigree?
   • A graphic way to represent how traits are passed down through generations.
2. What is hemophilia?
   • It is a blood disorder where the blood fails to clot properly. Queen Victoria’s pedigree shows how this disease was passed on through the generations and how some of the females were carriers of this disease.
3. What shapes/symbols are commonly used in pedigrees?

• • Squares usually represent males, while circles represent females.
  • Shaded shapes indicated a person had the trait.
  • A horizontal line connects married individuals.
  • A vertical line represents the offspring of two individuals.

IMAGES CREATED BY GAVS (FREEPIK)