Corn Snake Genetics
Phenotype activity
By: Meredith Penland CCU GK-12 fellow
This activity gives students the chance to see different phenotypes of a corn snake, Elaphe
guttata, based on the coloration of each snake presented to them. Students are asked to find a
cross that will create a corn snake of a certain phenotype type. This activity covers the concepts
of dihybrid crosses, phenotype, genotypes, dominant traits and recessive traits.
State standards
This activity focuses on indicator B4-6. Students are supposed to understand how to predict
inherited traits by using the principles of Mendelian genetics (including segregation,
independent assortment, and dominance).
B-4. The student will demonstrate an understanding of the molecular basis of heredity.
Objectives
1.
2.
3.
4.
Students will be able to perform a dihybrid cross.
Student will problem solve to create the type of snake they need.
Students will have a complete understanding of dominant and recessive traits
Students will understand what a phenotype is and how it is different from a genotype.
Lesson Plan
Background information
It is important that students already know the basics of Mendelian genetics and how to
perform and monohybrid cross
1. Show students how to perform dihybrid cross using a variation of the mathematical foil
method.
2. Emphasize it is important to have four, two letter traits on each side of the 16 square
block.
3. Review the importance of behavior around animal
4. Have Mr. Reed assist with the snakes while you go over the power point lesson.
5. Power point includes different phenotypes of corn snakes, genes that code for color,
explain what wild type means.
See attached power point lesson
Activity
1. Students must apply what they have learned about the snakes to problem solving.
2. Students are asked to find a way to create an Anerythristic snake by crossing the
available snakes.
3. Students must perform 4 dihybrid crosses all resulting in an Anerythrisitc snake.
Assessment
A worksheet is provided
Teacher information
You can contact Mr. Ryan Reed and invite him to your biology class by email at
rcreed@coastal.edu. Check his website for more information
http://www.freewebs.com/rrherps/index.htm
Name_________________________Block_________________________Date_____________
Corn snake genetics
1. What are they two alleles code for color in a corn snake?
2. When referring to a phenotype, what does wild type mean?
3. Given the genotype rrBb, what is the phenotype of the corn snake?
4. Given that Mr. Reed has three phenotypes of corn snakes (wild type, amelanistic, and
snow) could he create the fourth phenotype, anerythristic?
5. What is the genotype for an anerythrisitc snake (no red pigment)?
6. Which parental genotypes could you cross to create an anerythrisitc snake? List all
possible crosses. Remember that Mr. Reed only has one wild type snake. Also remember that you only
know the phenotype of each snake.
7. Pick four of your crosses from question 6 and perform the dihybrid crosses in Punnett squares in
the space below. List genotype and phenotype ration for each Punnett square.