Investigators have found a new species bacteria that lives under both aerobic and anaerobic conditions. They hypothesize that different genes are expressed in each condition. What experiment could test this hypothesis and identify important genes?

Question

A.  Completely sequence the genome of the bacteria in both aerobic and anaerobic conditions
B.  Collect mRNA from both anaerobic and aerobic conditions and generate two cDNA libraries
C.  Measure levels of RNA Polymerase in both conditions
D.  Design primers to a specific region of the genome and sequence this region during both anaerobic and aerobic conditions

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 gene expression?
transcriptional.

  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

B.  Collect mRNA from both anaerobic and aerobic conditions and generate two cDNA libraries

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses gene expression.
· 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 Aerobic and anaerobic conditions refer to conditions with or without oxygen.

  Gather Content
· What do you already know about gene expression?
        o Gene expression is controlled at multiple levels: transcriptional, post-transcriptional, transational, and post-translational.
        o In bacteria, however, the most common and important level of regulation is transcriptional.

  Consider Possibilities
· Consider the different answer options. Which can you rule out?
        o Would an experiment to sequence the genome address the hypothesis? No, because the genome always stays the same, and the hypothesis was specifically about gene expression.
        o Would an experiment to PCR a region of the genome address the hypothesis? No, because the entire genome will remain the same in both conditions, and the hypothesis was specifically about gene expression.
        o Would an experiment to measure levels of RNA Polymerase address the hypothesis? No, because levels of RNA Polymerase are unlikely to change, and would not be a likely way of regulating gene expression.

  Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Would creating two cDNA libraries address the hypothesis? Yes, because that would allow you to see differences in transcript levels for different genes in each condition.
   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 how to test a hypothesis about gene expression in two different conditions.
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that the hypothesis was saying that gene expression would be different, and that basically means the set of expressed mRNAs?