 |
Name ______________________ Date ____________________
Firebreathing Activity: Understanding a sex linked, recessive trait
GenScope File: Firebreathing.gs
Bring up the Firebreathing.gs file by
double clicking on it. When GenScope opens, you will see a pedigree
window set to show fire. There are three dragons in it -- two females and
one male. Note that you cannot see the genotype of any of the three.
|
1. Your task will be to figure out how firebreathing is inherited. Let's begin with some predictions. If Joe and Jennie have kids, do you think any of them will be firebreathing? Circle your answer below.
a. I believe that Joe and Jennie can have firebreathing children.2. How about Joe and Jane? If Joe and Jane have kids, do you think any of them will be firebreathing? Circle your answer below.b. I do not believe that Joe and Jennie can have firebreathing children.
a. I believe that Joe and Jane can have firebreathing children.b. I do not believe that Joe and Jane can have firebreathing children.
3.
OK, now try it. First, use the cross tool to mate Joe and Jennie. Then
circle all of the statements below that are TRUE.
a. All of Joe and Jennie's kids are firebreathing.4. After you've circled the true statements, use the scissors tool to remove the pedigree. Now use the cross tool to mate Jane and Joe and circle the TRUE statements below:b. Some of Joe and Jennie's kids are firebreathing.
c. All of Joe and Jennie's firebreathing kids are girls.
d. Some of Joe and Jennie's girls are firebreathing, some are not.
e. None of Joe and Jennie's girls are firebreathing.
f. All of Joe and Jennie's boys are firebreathing.
g. Some of Joe and Jennie's boys are firebreathing and some are not.
h. None of Joe and Jennie's boys are firebreathing.
a. All of Jane and Joe's kids are firebreathing.5. Do you think it's possible for Joe and Jennie to have a firebreathing boy? Use the cross tool again to give them a bigger family and see whether they could ever have a firebreathing son. What happened?b. Some of Jane and Joe's kids are firebreathing.
c. All of Jane and Joe's firebreathing kids are girls.
d. Some of Jane and Joe's girls are firebreathing, some are not.
e. None of Jane and Joe's girls are firebreathing.
f. All of Jane and Joe's boys are firebreathing.
g. Some of Jane and Joe's boys are firebreathing and some are not.
h. None of Jane and Joe's boys are firebreathing.
6. Explain what you think is the reason that this happened. Hint: take a look at the chromosomes of the children. What chromosome is the firebreathing gene on? Why is this important?
7. Let's take this one step further. Do you think they could ever have firebreathing grandchildren?
8. Cross two of the F1 generation and see what happens. Hint: take a look at the chromosomes of the F1 generation and choose the parents of the generation carefully.
Were any of the grandsons in the F2 generation firebreathers?
9.
Based on the information you have gathered during this exercise, what do
you think Jane, Jennie and Joe's alleles for firebreathing are? Circle
all the answers in the table you think are possible.
| Jane | FF | Ff | ff | F- | f- |
| Jennie | FF | Ff | ff | F- | f- |
| Joe | FF | Ff | ff | F- | f- |
[ Table of Contents ] [ Previous Activity: Mutations ] [ Next Activity: Hitchhiker's Thumb ]