Which of the following two enzymes are needed to construct a cDNA library?

Question

A.  reverse transcriptase and DNA ligase
B.  reverse transcriptase and Taq polymerase
C.  DNA ligase and Taq polymerase
D.  Taq polymerase and RNA polymerase

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 DNA libraries?
 
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.  reverse transcriptase and DNA ligase

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses DNA library construction.
· 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 A cDNA library is a collection of DNAs that represent DNA copies of a mixture of mRNA molecules from a sample.
 
Gather Content
· What do you already know about DNA libraries?
        o Libraries are collections of DNA pieces.
        o cDNA libraries are DNA copies of mRNAs.
        o The DNA is synthesized from mRNAs using reverse transcriptase.
 
Consider Possibilities
· Consider the different answer options. Which can you rule out?
        o Would Taq polymerase help you make a cDNA library? No, that enzyme is used to make more DNA copies of DNA.
        o Would RNA polymerase help you make a cDNA library? No, that enzyme is used to synthesize RNA.
 
Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Would reverse transcriptase help you make a cDNA library? Yes, that enzyme will allow you to make cDNA copies of the mRNAs.
        o Would ligase help you make a cDNA library? Yes, that enzyme will allow you to ligate the cDNAs into the vectors.

  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 what enzymes you need to make a cDNA library.
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that you need reverse transcriptase to make the cDNA, and ligase to put it in the vector plasmids?