If a bacterium containing a mutation in the avirulence gene lands on a plant that has the corresponding R gene, the bacterium may not initiate rapid cell death in the plant.

Question

Answer the following statement true (T) or false (F)

Answer 1

True

Clarify Question
• What is the key concept addressed by the question?
        o This question is asking about the extent of the effect of a mutation in an avr gene.
• What type of thinking is required?
        o This question is asking you to evaluate the consequences of a mutation in an avr gene in a bacterium.
• What key words does the question contain and what do they mean?
        o Resistance gene, which is a gene that gives a plant protection against a disease.
        o avr gene, which is a gene that aids in the recognition of a pathogen.

Gather Content
• What do you already know about about avirulence and R genes? How does it relate to the question?
        o Proteins are constructed from recipes specified in the DNA of an organism.
        o DNA is subject to change via mutation.
        o Resistance genes produce R proteins.
        o R proteins interact with avirulence (avr) proteins in pathogens, signaling the presence of the pathogen to the plant's defense system.
        o Once a pathogen is recognized, rapid cell death may occur in the plant to prevent the spread of the pathogen.

Consider Possibilities
• What other information is related to the question? Which information is most useful?
        o If the avr gene mutates, the protein will change.
        o If the avr protein changes, the R protein will not recognize it.
        o If recognition does not occur, the defense pathway will not take place.
        o Without the defense pathway, the plant is vulnerable to the pathogen.

Choose Answer
• Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o As long as genes and gene products such as the avr protein can change, as is always possible through mutation, it is possible that recognition will not occur between the R protein and the avr protein. If this recognition does not occur, the defense pathway does not occur and the plant is not protected from the pathogen.

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?
• Evaluate level:
This question asked you to evaluate the effects of mutation in a gene involved in pathogen recogntion. Answering this question correctly depended on your ability to evaluate the possibility of genetic change. If you got the correct answer, well done! If you got an incorrect answer, where did the process break down? Did you remember that recognition is based on the structure of the R protein and the avr protein, or the criteria to compare genetic change can cause a change in the shape of a protein? Did you have trouble weighing the merits of genetic change and a corresponding change in protein shape to determine the correct answer?