Name: ______________________________________  Date:_______________

 

POLYGENIC TRAITS

 

 

Introduction:

 

Polygenic traits or quantitative genetics is a topic that is often skipped by biology teachers. It seems that teachers have no real model or lab in which to demonstrate this complicated topic. We have found that if we used pennies to represent genes (heads dominant; tails recessive), we could show students how people fall into a bell curve type arrangement and how different heights are passed on to children.

Polygenic traits are traits that are controlled by more than one gene, ie. height, weight, hair color, skin color (basically anything dealing with color). This allows for a wide range of physical traits. For example, if height was controlled by one gene A and if AA = 6' and Aa = 5'7" and as = 5', then people would either be 6', 5'7", or 5'. Since height is controlled by more than one gene, a wide range of heights is possible.

 

Materials:

 

6 pennies

graph paper

colored pencils

 

Procedure:

 

1. Each group will carefully flip all six coins on the table at the same time.

 

2. Record the number of heads and tails that result from the flip in Data Table 1.

 

3. Continue to flip the coins and continue to record data that result until the table is complete.

 

4. Complete Data Table 2 by adding up the number of times the following situations occurred:

0 tails and 6 heads, 1 tails and 5 heads, 2 tails and 4 heads, 3 tails and 3 heads, 4 tails and 2 heads, 5 tails and 1 heads, 6 tails and 0 heads.

 

5. Record your results from Data Table 2 on the board with the class results.

 

6. Record the class results in Data Table 2.

 

7. Construct a bar graph from the CLASS data. The number of heads and tails will go on the X axis (you will have seven bars) while the number of times that the situation occurred will go on the Y axis. Please use colored pencils to make your graph. Please put an appropriate title on your graph.

 

8. Answer questions.

 

 

 

 

Results:

Data Table 1:

 

Flip Group

# of Heads

# of Tails

1

 

 

2

 

 

3

 

 

4

 

 

5

 

 

6

 

 

7

 

 

8

 

 

9

 

 

10

 

 

 

            Data Table 2:

 

Flip Situation

Your Group Total

Class Total

(Graph these results only!!)

0 tails, 6 heads

 

 

1 tails, 5 heads

 

 

2 tails, 4 heads

 

 

3 tails, 3 heads

 

 

4 tails, 2 heads

 

 

5 tails, 1 heads

 

 

6 tails, 0 heads

 

 

 

 

 

Conclusion:

 

Use the following Height Table to answer the questions below.

 

Flip Situation

Height

0 tails, 6 heads

6 feet 1 inch

1 tails, 5 heads

5 feet 11 inches

2 tails, 4 heads

5 feet 9 inches

3 tails, 3 heads

5 feet 7 inches

4 tails, 2 heads

5 feet 5 inches

5 tails, 1 heads

5 feet 3 inches

6 tails, 0 heads

5 feet 1 inch

Remember: Heads are dominant alleles for this lab activity and tails are recessive alleles.

 

 

 

 

 

Questions:

 

  1. Do parents give all or half of their genetic material to their children?
  2. If a man is 5 feet 7 inches tall, he has 3 heads (dominant alleles) and 3 tails (recessive alleles). He can give three genes to his child. These three genes can be given randomly (Mendelís Principle of Independent Assortment).
    1. He can give 3 dominant alleles and 0 recessive alleles.
    2. He can give 2 dominant alleles and 1 recessive allele.
    3. He can give 1 dominant allele and 2 recessive alleles.
    4. He can give 0 dominant alleles and 3 recessive alleles.

These are all the possible combinations that he can give his child. The height of the mother will dictate the alleles that she will give the child. The combinations of the motherís alleles and the fatherís alleles will dictate the height of the child.  Using this information, if a male is 5 feet 9 inches tall, it means he has 4 dominant alleles and 2 recessive alleles. He will only give three alleles to his child. What are the possible combinations of alleles that he can give?

a.       He can give ______dominant alleles and ______recessive alleles.

b.      He can give ______ dominant alleles and ______ recessive alleles.

c.       He can give ______ dominant alleles and ______ recessive alleles.

 

3. If a father is 5 feet 7 inches and a mother is 5 feet 5 inches, is it possible for them to give their child the necessary genes so the child can be 5 feet 11 inches tall? Explain how this is possible.

 

 

 

4. If two parents are both 5 feet 7 inches, is it possible to have a child that is 6 feet tall?  Explain how this is possible.

 

 

 

5. If the father is 5 feet 7 inches tall and the mother is 5 feet 3 inches tall, what is the shortest height their child could have? Explain your answer.

 

 

 

6. If the father is 5 feet 7 inches tall and the mother is 5 feet 3 inches tall, what is the tallest height their child could have? Explain your answer.

 

 

 

 

7. List 3 other polygenic traits besides height.

 

 

 

8. What does your graph of the class results for height look like?

 

 

 

 

Graph: