As a scientist working for an anti-bioterrorism task force, you are asked to evaluate some biological samples for the presence of Yersinia pestis, the organism that causes the plague. After confirming that the samples do contain Y. pestis, you instruct your team to begin sequencing the strain. Since the genome sequence of Y. pestis is already known, why would sequencing this strain be useful?

Question

A.  To provide better data for the genome database
B.  To establish the course of infection, and determine whether the strain is altered by causing infection
C.  To help determine the source of the strain, and learn whether it has been genetically engineered
D.  To create a vaccine for this particular strain

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 genome analysis?

  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

C.  To help determine the source of the strain, and learn whether it has been genetically engineered

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses genome analysis.
· What type of thinking is required?
        o This question is asking you to weigh and judge, or evaluate, evidence to choose the best of the possible answers.
· What key words does the question contain and what do they mean?
        o Bioterrorism is terrorism that uses disease organisms to harm and frighten people.
        o Yersinia pestis, the organism that causes the plague, is a Gram-negative bacterium that has been responsible for killing millions of people in historical outbreaks.
        o The genome sequence is the complete sequence of its DNA. Since Yersinia is a bacterium, sequencing the small genome is not as difficult as for a eukaryote.

  Gather Content
· What do you already know about genome analysis?
        o We have learned that every organism carries small polymorphisms – little sequence differences in the genome.
        o How might these be useful here?

  Consider Possibilities
· Consider the different answer options. Which can you rule out?
        o Would sequencing the genome help by providing better data for the genome database? No, that’s not really a big priority.
        o Would sequencing the genome help by establishing the course of infection, and determining whether the strain is altered by causing infection? No, that’s not likely.
        o Would sequencing the genome help to create a vaccine for this particular strain? No, if a vaccine was being developed they would focus on particular proteins, not the whole genome.

  Choose Answer
  · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Would sequencing the genome help to determine the source of the strain, and learn whether it has been genetically engineered? Yes. Small differences, or polymorphisms, could connect the strain to a source. This would help identify who was spreading it. Furthermore, it would be important to know whether it had been engineered to be even more deadly.

  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 why you would sequence a genome of a possible bioterrorism germ.
        o The question required you to weigh and judge, or evaluate, evidence to choose the best of the possible answers.
        o Did you recognize that sequencing the genome could reveal polymorphisms to help trace the strain to its source?
        o Genome sequencing might also reveal a genetically engineered change to the genome.