When a human egg cell is fertilized with a sperm cell there are
many possible gene combinations. This results in great variety of
human traits, and the probability of any two humans having identical
genetic traits is very small.
By the end of this activity students should understand the concept
of probability in regard to gene combinations during fertilization.
This activity is a model of the process of independent and random
assortment of genes. Students select "genes" from the
egg and sperm cells and observe the resulting combinations in the
empty cans or paper sacks
1. Use two sets of empty containers, such as cans or sacks, to hold
the "genes" for the egg and sperm cells. One set is for
the genes in the sperm cell, the other set for the genes in the
egg cell. The number of containers will correlate to the number
of traits you want to study.
2. Use bottle tops as models for genes. Mark them as either dominant
or recessive for a particular trait. Then put each "gene"
into a separate container.
3. Choose, without looking, one "gene" from each parent
and record the resulting trait in the "offspring."
4. Keep a table of the results. Draw a sketch of the resulting offspring.
5. Calculate the mathematical probability of any two of these "offspring"
having identical traits or gene combinations.
A follow-up idea is to eliminate the "random" factor.
Let students do the activity again, this time deliberately selecting
the genes they want. Have them compare this "genetic engineering"
activity to the random selection activity done previously.
After selecting genes for all the traits, have students draw a picture
of the offspring.
Students can compare and discuss results. Were any two offspring
Standards and Benchmarks
Standard 4: Understands the principles of heredity and related concepts
4. Knows that hereditary information is contained in genes (located
in the chromosome of each cell), each of which carries a single
unit of information; an inherited trait of an individual can be
determined by either one or many genes, and a single gene can influence
more than one trait
5. Knows that the characteristics of an organism can be described
in terms of a combination of traits; some traits are inherited and
others result from interactions with the environment