You are the scientific consultant for a television show about forensic analysis. In an upcoming episode, investigators will compare the DNA of a suspect and a DNA sample collected from the victim’s fingernails. You are to write up a brief explanation of the technique required for comparing the DNA. Which technique should you explain?

Question

A.  DNA fingerprinting
B.  Fluorescent in situ hybridization
C.  RNAi
D.  RT-PCR

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

  Gather Content
· What do you already know about molecular techniques?

  Consider Possibilities
· Consider the different answer options. Which can you rule out?

  Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

  Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

A.  DNA fingerprinting

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses molecular techniques.
· What type of thinking is required?
        o This question is asking you to take what you already know and apply it to this unfamiliar situation.
· What key words does the question contain and what do they mean?
        o Forensic analysis is the science of analzying data from crime scenes.

  Gather Content
· What do you already know about molecular techniques?
        o There are a variety of molecular techniques for many purposes.
        o Some are used on RNA, some on proteins, and some on DNA.

  Consider Possibilities
· Consider the different answer options. Which can you rule out?
        o Would fluorescent in situ hybridization allow the investigators to compare the DNA? No, because FISH is used to detect one particular small target sequence in a mixture of DNA, not to compare two samples overall.
        o Would RNAi allow the investigators to compare the DNA? No, because that is used to inhibit expression of a gene.
        o Would RT-PCR allow the investigators to compare the DNA? No, because that is used to create DNA copies of mRNAs.

  Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Would DNA fingerprinting allow the investigators to compare the DNA? Yes, that is the purpose of that technique.

  Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked which technique is used to identify the source of DNA at a crime scene.
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you remember that DNA fingerprinting is the tecnique used to compare DNA samples?