Three scientists are using different forms of PCR for their research. Abby wants to determine changes in gene expression levels in a tissue, so she uses ______. Bob is trying to extract genetic information from a wooly mammoth fossil, so he uses ______. Chris needs to express a gene in bacteria that matches the form expressed in kidney cells, so she uses ______.

Question

A.  Quantitative RT-PCR;  PCR;  RT-PCR
B.  PCR;  quantitative RT-PCR;  RT-PCR
C.  RT-PCR;  PCR;  quantitative RT-PCR
D.  RT-PCR;  quantitative RT-PCR;  PCR
E.  Quantitative RT-PCR;  RT-PCR;  PCR

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

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

  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.  Quantitative RT-PCR;  PCR;  RT-PCR

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses PCR 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.

  Gather Content
· What do you already know about PCR techniques?
        o PCR, polymerase chain reaction, mimics the processes of DNA replication. An individual reaction is cycled through a series of steps where each step is analogous to a step in DNA replication: Denaturation, Annealing, and Synthesis. It starts with small amounts of DNA and makes more DNA.
        o RT-PCR, reverse transcription PCR, makes amplified DNA from mRNA. It can allow you to create an intron-less “gene” matching an expressed mRNA.
        o Quantitative RT-PCR is a sensitive way to determine relative levels of expression of an mRNA in a particular tissue or sample.

  Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Abby wants to determine changes in gene expression levels in a tissue. She needs a way to quantify mRNA levels, so she uses quantitative RT-PCR.
        o Bob is trying to extract genetic information from a wooly mammoth fossil. He should amplify DNA, not RNA, since DNA is more stable over millions of years. He uses PCR.
        o Chris needs to express a gene in bacteria. Bacteria cannot do alternative splicing, and she wants to use a particular expression variant from kidney cells. So she uses RT-PCR to create a DNA copy of the mRNA from those cells.
   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 The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that PCR is best when simple amplification of DNA is needed?
        o Did you recognize that RT-PCR is used when you need to create a DNA copy of an mRNA?
        o Did you recognize that quantitative RT-PCR is best for determining changes in levels of an mRNA?