Lesson Plan #: AELP-GET0200
Introduction to Genetics
An Educator's Reference Desk Lesson Plan
Submitted by: Robert Petrunak
School/University/Affiliation: University of Pittsburgh at Johnstown
Endorsed by: Bernard Poole
University of Pittsburgh at Johnstown
Date: January 26, 2001
Grade Level: 9, 10
Duration: 50 minutes
Description: This lesson introduces students to genetics. Students learn about Mendel's work, genetic terms (homozygous, heterozygous, phenotype, genotype), the construction of Punnett Squares, and the construction of Pedigree Tests.
Goals: SWBAT (Students will be able to) determine and predict the genotypes and phenotypes of parents and their offspring.
- SWBAT determine and predict the genotypes and phenotypes of parents and their offspring.
- SWBAT list and discuss the parts of Mendel’s Law of Segregation.
- SWBAT define homozygous, heterozygous, phenotype, and genotype.
- SWBAT use a Punnett Square.
- SWBAT perform a Pedigree Test.
- Homozygous - Pair of identical alleles for a character.
- Heterozygous - Having 2 different alleles for a character.
- Phenotype - An organism's outward appearance.
- Genotype - An organism’s genetic makeup.
- Punnett Square - A square used to show all the possible combinations of gametes.
- Pedigree Test - A test in which you look at the offspring of parents to determine the genotypes of the parents.
Ask students to take a look at their physical features and to think about how their features compare with those of their parents. Display the transparencies and begin discussion about genetics. (Go over Mendel's work, genetic vocabulary, and the Punnett Square.) During discussion of the Punnett Square, give students the hand-out entitled, "Matings Involving Segregation at One Gene." Conclude the transparencies by discussing the Pedigree Test. Give students the hand-out which shows four examples of Pedigree charts. Students can refer to these charts when they are completing the next activity.
Divide students into small groups. Inform them that they will have an opportunity to create Pedigree charts. Pass out the worksheet called "Pedigree Activity," which involves eye color. From the information provided (4 children: 2 brown-eyed and 2 blue-eyed), students will predict the genotypes of the parents and grandparents and construct a Pedigree chart showing the traits for the grandparents, parents, and children. [ Author's Note: Since the ratio of brown to blue is 1:1, students can predict that one parent is homozygous recessive and the other is heterozygous. It doesn't matter which parent is which. The Pedigree chart for the parents and children would look like Pedigree chart D.]
As an extension to the eye color activity, have students choose one offspring. Ask students to predict the children that offspring would have if the offspring mated with a homozygous dominant, a homozygous recessive, or a heterozygous mate (remind students that brown-eyed is dominant). Students should compare the different outcomes in each instance.
As an alternative to eye color, students can construct Pedigree charts for other traits such as earlobes (free earlobes dominant and attached earlobes recessive) or tongue rolling (rolling dominant and non-rolling recessive).
If there is time remaining at the end of class, conduct a "Quickfire Review." Concepts that can be reviewed include the following:
- List and discuss the parts of Mendel’s Law of Segregation.
- Define homozygous, heterozygous, phenotype, and genotype.
- List other traits that students feel are inherited. Of the traits listed, what do students feel are the dominant and recessive traits of each?
Assessment: Students' progress will be determined through teacher observation during the Pedigree activity. Collect students' worksheets to check the accuracy of the Pedigree charts.
Useful Internet Resources:
* The Biology Project ~ Mendelian Genetics
* Pea Experiment
Special Comments: Technology Integration Scenarios:
If a computer and LCD panel are available, connect to the "Biology Project ~ Mendelian Genetics" web site. Complete the monohybrid cross test set with the students as a review of the lesson.
If a computer lab is available, have students visit the "Pea Experiment" site. Students can simulate Mendel's experiment by mating pea plants. Have the students carry out the pea experiment after the lecture.