Download Genetics Coin Toss Lab

Name______________________________________Block_____Date______________
Genetics Coin Toss Lab
PRE-LAB DISCUSSION:
In heredity, we are concerned with the probability that a particular gene or
chromosome will be passed on through the egg or sperm to the offspring. As you know,
genes and chromosomes are present in pairs in each individual, and segregate during
meiosis. There are two possible alleles that each egg or sperm might obtain from the
individual’s pair, but it actually receives only one of them. If the probability of getting
either one is equal, this probability can be expressed as ½ or 50%, like the probability of
getting heads or tails when you flip a penny.
When combining two gametes to form a new organism, a simple 50/50 ratio does
not fully represent this process. We need to calculate the probability that a single allele
will be transferred into a gamete from an individual in addition to the probability it will
then combine with a specific allele of a separate gamete from a different individual. The
following activity focusing on Mendel’s pea plant experiments will help you see this.
PURPOSE:
 What is probability?
 What does random mean and how does it apply to genetics?
 How does probability relate to Punnett Squares and the offspring that are shown?
 To demonstrate the genetic probability of Mendel’s pea plant experiments.
MATERIALS
 2 Pennies
 2 Nickels
PART A: Flower Color
PROCEDURE:
1. Use 2 pennies. One penny represents a pair of genes in a parent. The other penny
represents the same pair of genes on the other parent.
 Heads = A the dominant gene (purple)
 Tails = a the recessive gene (white)
2. Both parents are heterozygous.
 What are the genotype and phenotype of parent #1?

What are the genotype and phenotype of parent #2?
3. Using the Punnett Square on the next page calculate the Expected Probability. Record
it as a percentage in the Data Table.
4. Toss the coins together. They can only turn up: AA, Aa, or aa
 Remember: each coin represents each parent and each toss can only turn up
one way, therefore, a parent can give only one gene of a pair.
6. Toss the coins 50 times and record your results under Group Tally on the Data Table.
7. Total up your tally marks and list your results on the board as directed by your
teacher. Record the class’s totals in your Data Table.
Name______________________________________Block_____Date______________
8. Using the class’s totals determine the percentage and record them under the
Calculated Probability on your Data Table.
Punnett Square:
Parent #1
Parent #2
PART A Data Table
Genotype
Phenotype
Expected
Probability
%
Group Tally
Class
Total
(TOTAL
#:
)
Calculated
Probability
%
AA
Aa
aa
QUESTIONS
1. Describe the difference between your group’s results and the class’s totals.
2. How close did your Calculated Probability come to your Expected Probability?
PART B: Seed color and texture
PROCEDURE:
1. Use 2 pennies and 2 nickels
2. 1 penny and 1 nickel represent 2 pair of genes in a parent. The other penny and
nickel represent the same pair of genes in the other parent. Ask your teacher to sign
this page.
 COLOR gene:
Penny Heads = Q (yellow), Penny Tails = q (white)
 TEXTURE gene: Nickel Heads = R (rough), Nickel Tails = r (smooth)
3. Both parents are heterozygous for both traits.
 What are parent #1’s genotype and phenotype for both traits?

What are parent #2’s genotype and phenotype for both traits?
Name______________________________________Block_____Date______________
4. Using the Punnett square below, record the resulting offspring. Calculate the
Expected Probability and record it as a percentage in your Data Table.
6. Toss all four coins (at the same time) 50 times and record the results on your Data
Table.
7. Total up your tally marks and list your results on the board as directed by your
teacher. Record the class’s total’s in your Data Table.
8. Determine the percentage for the class’s totals and record it under the Calculated
Probability on your Data Table.
Punnett Square
Parent #1
Parent #2
PART B Data Table:
Genotype
Penny
Nickel
QQ
RR
QQ
Rr
Qq
RR
Qq
Rr
QQ
rr
Qq
rr
qq
RR
qq
Rr
qq
rr
Combined
Phenotype
Expected
Probability
%
Group Tally
Class
Total
(TOTAL
#:
)
Calculated
Probability
%
Name______________________________________Block_____Date______________
QUESTIONS:
1. What fraction of actual phenotypes did the class record, i.e. how many yellow and
rough, white and smooth, etc?
2. How close are your calculated phenotypes to your expected percentages predicted?
3. What is probability?
4. What does random mean and how does it apply to genetics?
5. Why did we use the class’s totals to calculate the calculated probability?