Student Exploration: DNA Fingerprint Analysis
Vocabulary: codon, DNA, DNA fingerprint, genotype, identical twins, nitrogenous base, phenotype, trait
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
The two navy officers shown at left are identical twins. Why do you think identical twins look so similar?
Most brothers and sisters don’t look exactly the same. What causes most siblings to have different appearances?
Most of an organism’s traits, or characteristics, are coded for by DNA. Traits are determined by a unique sequence of nitrogenous bases in the DNA molecule.
Except for identical twins, the order of every individual’s nitrogenous bases is unique. Scientists use this fact when studying DNA fingerprints—patterns of bands made from analyzing a strand of DNA. In the DNA Fingerprint Analysis Gizmo™, you will analyze DNA fingerprints of frogs.
1. Select the POPULATION tab. What are the three main traits that vary between the frogs?
2. Which frog would you expect to have the most similar DNA to frog A? Why? ____________
|Activity A: |Get the Gizmo ready: |[pic] | | |Select the FIND THE TWINS tab. | | |Identical twins | | |
Question: How are DNA fingerprints used to analyze relationships?
1. Observe: Look at the three frogs on the TWINS tab. How does their appearance compare?
2. Predict: What do you expect the DNA fingerprints of the three frogs to look like? _______
3. Identify: Drag frog A to the scanning station and click SCAN. Drag the resulting DNA fingerprint to the bin at the upper right of the Gizmo. Each band on the fingerprint represents a single nitrogenous base of DNA. The band is dark if that base is present and pink if that base is absent.
Scan frogs B and C. Drag their DNA fingerprints into the bin. If two frogs are identical twins, they will have exactly the same DNA fingerprint. Compare the three fingerprints.
Could any of these frogs be identical twins? If so, which frogs? _______________________
4. Analyze: DNA is composed of four different nitrogenous bases. For the type of DNA fingerprint used by the Gizmo, a complete DNA fingerprint would have scan readouts for all four nitrogenous bases. Knowing this, why can you not be entirely certain the frogs are identical twins using the simplified fingerprints on the Gizmo?
5. Apply: Click New. For the new frogs, find the possible pair of identical twins.
A. Which two frogs could be identical twins? _________________________________ B. How do you think DNA fingerprints can be used in the real world to identify relationships between individuals?...
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