Independent Assortment Simulation
Name _________________________ Block_____
Mendel’s (more on him later) second law of heredity is known as the law of independent assortment.
This law states that during meiosis the two chromosomes of a pair segregate independently of all the other
homologous pairs. Yes, this is considered one of the most difficult concepts to understand.
In order to make sense of this concept it is best to introduce this process during meiosis rather than later
in genetics. Remember that the genes are on the chromosomes and in order to understand the movement of
these genes into the gametes during fertilization, it helps to understand the movement of the entire
chromosomes first. The following activity should help you to follow the movement of chromosomes with
beans and later the movement of the genes attached to the chromosomes.
In this activity, your group will receive 4 bags. The bags are used to keep the homologous pairs separate
and to hide what’s in the bag as you “withdraw” the bean to produce the random nature of independent
assortment. Within these bags are 2 sets of four homologous bean chromosomes. The lighter-colored bean
represents 1 set of homologous chromosomes and the darker-colored bean represents 1 set of homologous
chromosomes. The morphology (structure) of each set of homologous chromosomes in all 4 bags is the same.
This may seem unrealistic to you but actually it is not uncommon for the morphology (structure) of homologous
chromosomes to be the same. In humans, chromosomes 6-12 are similar and are different only by the different
genes that make up the chromosomes.
Overview: While “withdrawing” a bean randomly from each bag, you will simulate the independent way that
homologous pairs are separated from each other. In the data table below, you will record which kinds of
chromosomes would go into the resulting cell in telophase 1. The bean chromosome will be returned to the bag
each time so that you can repeat your random “drawing” a total of 12 times.
Objective: Students will simulate the random separation of 4 sets of homologous chromosomes.
Protocol: 1. In your group, share the responsibilities of withdrawing one bean (chromosome) from each of the
4 bags of homologous chromosomes, recording the results in the data table, replacing the bean in the correct
bag, and re-drawing 11 more times. 2. When finished, share your data and then answer the conclusion
questions.
# of draws
Bag 1
1
2
3
4
5
6
7
8
9
10
11
12
Legend: D = Dark
L = Light
Results of Draws
Bag 2
Bag 3
Bag 4
Conclusion Questions:
1.
Describe the results of the simulation, specifically discussing the segregation of the homologous
chromosomes.
2.
What do homologous chromosomes have in common?
3.
Indicate where this bean simulation would have occurred in meiosis.____________________________
4.
What process increases genetic diversity besides independent assortment?
5.
What represented the centromere in this activity? ___________________________________________
6.
If your hands represented the spindle fibers and separated the sister chromatids, what phase in meiosis
is demonstrated? ______________________________________-
7.
What does independent assortment impact, making it such an important concept?
8.
In order to actually create eggs and sperm, what further steps would have had to occur?