EXERCISE 1
GENETICS OF COAT COLOR IN HORSES

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Use information from the World Wide Web to answer the questions below.

The site that you will be using to answer these questions is Coat Color Genetics from the University of California at Davis. As you will see, the color of a horse's coat is determined by the interaction of a number of different genes.

Print out the worksheet below and use the link above to answer the following questions.

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Name _____________________________________________________

 

Link and Think: Genetics of Coat Color in Horses

Starting at the Coat Color Genetics Web site, read first the Gene W then the Gene E sites to find the information needed to complete this worksheet. (http://www.vgl.ucdavis.edu/~lvmillon/coatcolor/coatclr3.html)

Read the introductory section and the section about the W gene. This gene controls whether or not any pigment can be deposited in a horse's hair. Using that information as your guide, circle your answers to the following questions.

1. What is the genotype at the W locus of an albino horse?

WW

ww

2. What color will a horse that is homozygous for the dominant allele at the W locus (WW) be?

White

Gray

Black

Red

3. What color will a horse that is heterozygous for the dominant allele at the W locus (Ww) be?

White

Gray

Black

Red

4. If a WW mare is crossed with a Ww stallion what proportion of the foals will be albino?

None

1/4

1/2

3/4

All

5. If the same WW mare is crossed with a WW stallion, what proportion of the foals will be albino?

None

1/4

1/2

3/4

All

Before you answer the next set of questions, read the section about the E gene. This gene determines whether or not a horse deposits black pigment in its hair. Then circle your answers to the following questions.

6. Will a horse that is genotype wwEE have any black hair?

Yes

No

7. Will a horse that is genotype wwEe have any black hair?

Yes

No

8. Will a horse that is genotype wwee have any black hair?

Yes

No

9. If a WWEE mare is crossed with a wwEE stallion, what proportion of the foals will be white?

None

1/4

1/2

3/4

All

10. If a wwee mare is crossed with a wwEE stallion, what proportion of the foals will have some black hair?

None

1/4

1/2

3/4

All

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Check your work here.

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