1. 7D59 Gene Combo
Coin Toss Model

2. Background
An Austrian monk named Gregor Mendel studied the genetics of pea plants in 1860.
Based on the results of his experiments with seed color and other traits, Mendel proposed a model for how organisms inherit traits from their parents.

3. Hypothesis
Here you will investigate a hypothesis that is very similar to Mendel’s hypotheses.
Tossing coins is one way to model how genes are passed from parent to offspring. All of Skye and Poppy’s offspring, including two named Ocean and Lucy, have blue tails. Why do some of Ocean and Lucy’s offspring have orange tails. Find out by modeling Gen 3.

4. Coin Tossing Model
A coin toss (heads or tails) represents the one version of a tail color gene from a parent critter. Heads = blue color, Tails = orange color.
A future offspring critter receives one of the tail color genes from each parent.
Each side of the coin represents 1 of the 2 tail color genes carried by each Generation Two critter, such as Ocean and Lucy.

5. Dominant Gene
Blue tail color is dominant to orange. So if a critter has at least 1 blue version of the gene, its tail is blue. A critter has orange tail only if it has NO blue versions of the tail-color gene.
If T=blue tail gene and t=orange tail gene, tail color trait is called the phenotype. The gene and letter combinations, like TT, Tt, tT, or tt, are called the genotype.

6. Challenge Question
How can tossing coins help you understand how organisms inherit genes from parents? Write your paragraph answer in your lab book.

7. Procedure A
In your group of 4 students, divide into two pairs. Each pair should complete steps 2-5.
Decide who will toss a penny to represent Ocean; the other person will toss a penny to represent Lucy. The outcome of each toss determines the tail-color gene each parent passes on to each critter pup.
Each person will toss a penny. Shake it well.

8. Offspring Genes TT, Tt, tT, or tt Offspring Tail Color blue or orange
Procedure B
4. Work with your partner to fill in the first row of your worksheet. Use these symbols for genes: heads=T=blue tail gene, tails=t=orange tail gene For example, if Ocean’s coin toss results in heads (T), and Lucy’s coin toss results in tails (t), your first entry will be:
Offspring
Ocean T/t
Lucy T/t
Offspring Genes TT, Tt, tT, or tt
Offspring Tail Color blue or orange 1 T t Tt
blue

9. Procedure C
5. Repeat Steps 2-4 until you have filled in every row of the table. 6. Prepare a simple results-summary table. Include the total number of times you got each gene combo (TT, Tt, tT, or tt) and the number of times you got each tail color (blue or orange). 7. Check your work and return results to teacher.

10. D59 Gene Analysis: 1 paragraph
If you toss two coins 100 times, predict how many times the outcome would be:
head-head b) head-tail c) tail-head d)tail-tail
Are you sure of getting exact results in #1?
Look back at D58 Creature Features. How do the Generation 3 results compare to these?
Write your own definition of dominant trait. Does it always mean that every time a pair of critters mate, most offspring will be blue tail?