Glycogen Storage Disease Type II (GSD II), also known as Pompe disease, is a metabolic disorder that leads to the accumulation of glycogen in muscles and neurons throughout the body. It is caused by a defect in an enzyme that is normally housed with other enzymes that are involved in breaking down large macromolecules. What organelle is most likely affected by this disease?

Question

A.  Lysosome
B.  Golgi body
C.  Nucleus
D.  Mitochondrion
E.  Rough ER

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 know about breaking down large macromolecules like glycogen? How does it relate to the question?

Consider Possibilities
· What other information is related to the question? Which information is most useful?

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.  Lysosome

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about the glycogen storage disorder Pompe disease.
· What type of thinking is required?
        o You are being asked to apply your knowledge of different organelles to predict which would be involved in the breakdown of large macromolecules like glycogen.
· What key words does the question contain and what do they mean?
        o Accumulation of glycogen – this means that glycogen is not being broken down as it is supposed to, causing it to accumulate in neurons.
        o Defect in an enzyme –the enzyme that normally breaks down glycogen has been mutated so that it can no longer catalyze this reaction.
        o The enzyme is housed with other enzymes that are involved in breaking down large macromolecules – the enzymes are housed together in an organelle.

Gather Content
· What do you know about breaking down large macromolecules like glycogen? How does it relate to the question?
        o Enzymes used to break down large macromolecules are typically housed in the lysosome.  If one of these enzymes has a mutation and no longer functions then the macromolecule that it degrades will accumulate.

Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o The endoplasmic reticulum and Golgi are involved in protein transport, but would not store enzymes used to break down large macromolecules.
        o The nucleus would encode genes for these enzymes, but would not contain the enzymes themselves.
        o Mitochondria are responsible for ATP production in the presence of oxygen.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The best answer is that these enzymes would be present in the lysosome along with other digestive enzymes.  The lysosome contains many enzymes, and if any of these are defective it can lead to the accumulation of large macromolecules like glycogen.  The accumulation of these large macromolecules eventually inhibit the normal function of the cell, causing a disease state in the patient.

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 you to apply your understanding of the functions of different organelles to explain where a defective enzyme would be located. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you understand that the question was asking for the location of enzymes involved in degrading large macromolecules?  Did you think that the question was asking about where these enzymes would be made in the cell?