Learning Objectives
Students will …
Compare the DNA fingerprints of several individuals.
Identify individuals that could be identical twins.
Use DNA fingerprints to identify codons that control certain traits.
Predict an individual’s phenotype using the individual’s DNA fingerprint.
Vocabulary codon, DNA, DNA fingerprint, genotype, identical twins, nitrogenous base, phenotype, trait
Lesson Overview
With the exception of identical twins, no two organisms have exactly the same DNA. Therefore, DNA is much more accurate than fingerprints or body markings for identifying an individual. DNA sequencing can also be used to diagnose genetic disorders and discover the relationship between a genotype and phenotype.
One powerful tool for determining DNA sequences is a DNA fingerprint. Using the DNA Fingerprint Analysis Gizmo™, students can identify possible twins and relate DNA sequences to frog traits.
The Student Exploration sheet contains two activities:
Activity A – Students use DNA fingerprints to identify possible identical twins.
Activity B – Students use DNA fingerprints to analyze the traits of various frogs.
Suggested Lesson Sequence
1. Pre-Gizmo activities ( variable)
To introduce students to the structure and function of DNA, work with the Building DNA and RNA and Protein Synthesis Gizmos. Review how the sequence of nitrogenous bases within the DNA molecule is divided into codons, and how each codon specifies a particular amino acid.
In addition, show students pictures of actual DNA fingerprints. Have students discuss how DNA fingerprints are similar to bar codes and how they can be used to compare the DNA of different individuals. Tell students they will learn more about how DNA fingerprints can be used while working with the DNA Fingerprint Analysis Gizmo.
2. Prior to using the Gizmo ( 10 – 15 minutes)
Before students are at the computers, pass out the Student Exploration sheets