Glycolysis, Gluconeogenesis, and the Citric Acid Cycle

CHEM A394 – Survey of Biochemistry Question Creation Set
Glycolysis, Gluconeogenesis, and the Citric Acid Cycle

Choose three of the four options and write a multiple choice question that addresses the prompt. Refer to the Guidelines document for a grading rubric and examples. A few reminders:

You can use any resource you like to understand the concept. This includes things you find on the internet. Please cite any sources you use as links.
Do not paraphrase questions from your sources unless you are explicitly given permission to do so.
Your work must be your own, but asking a classmate for feedback is just fine. (Asking a classmate to write your questions for you is not fine.)
If your question is too similar to a classmate’s question, you’ll both be asked to re-do your questions.
Each question needs to have four answer options.
Wrong answers are a great opportunity to show that you’ve thought through the

prompt and the concept.

Indicate which option is the correct option; use only one right answer.
You will not have an opportunity to revise your questions.

Option 1: Consider the ways that glycolysis and gluconeogenesis are reciprocally regulated. Create a multiple choice question that proposes an increase or decrease in a particular allosteric regulator, and asks which of four possible outcomes is the most plausible. The proposed outcomes must be specific. Wrong answers must involve critical thinking and discernment. Here is an example of this type of question from our unit on hemoglobin:

Q: An increase in 2,3-BPG levels will result in…

a. ThestabilizationoftheTstateandresultingincreaseinhemoglobin’soxygenaffinity.

The stabilization of the T state and resulting decrease in hemoglobin’s oxygen affinity.
The stabilization of the R state and resulting increase in hemoglobin’s oxygen affinity.
The stabilization of the R state and resulting decrease in hemoglobin’s oxygen affinity.

(Correct answer: b)

Option 2: Consider one of the enzymatic mechanisms for any of the glycolysis, gluconeogenesis, or citric acid cycle enzymes covered in your book. Draw one of the substeps including an explicit side chain or molecule. (In other words, you cannot choose a step that involves a generic base (“B”).) Propose a set of four mutations to one of the amino acids involved, and ask your imaginary student to select the most or least disruptive mutation. You may also, if you wish, propose more detailed outcomes, like reduced activity, reduced binding of a particular substrate, etc.

Loyola University New Orleans
Department of Chemistry & Biochemistry Allyn Schoeffler, PhD

Question Creation Set CHEM A394 11/11/2020 30 points

Option 3: We’ve discussed how the pyruvate dehydrogenase complex is regulated through phosphorylation and secondary allosteric control. Write a question that demonstrates your understanding of this regulation. Your question should take one of the following forms:

Form A: Your question should state that PDC activity has either increased or decreased. Your four answer options should describe situations that might have caused this change; only one of them should be correct.

Form B: Your questions should describe a situation: a mutation, a phosphorylation event, an increase or decrease in the expression level of a particular protein, etc. The four answer options should describe possible outcomes in terms of PDC activity; only one of them should be correct. (You may incorporate multiple layers of outcomes in order to satisfy the four-answer-option requirement. For example, you may choose to include both phosphorylation and activity impacts in your answers.)

Option 4: Propose, in your question, either the deactivation (via mutation) or overexpression of one of the citric acid cycle enzymes (not including the pyruvate dehydrogenase complex). Then, in your answer options, propose secondary outcomes for this event. Choose your TCA enzyme wisely! You want its perturbation to have an impact on one of the pathways connected to the citric acid cycle. In your answers, you can involve the production of specific molecules or classes of molecules (like amino acids). You can also invoke allosteric control of other pathways.

Here’s an example of a question of this sort, but for glycolytic enzymes:

Q: Imagine that phosphoglucose isomerase is overexpressed. Which of the following is a plausible secondary effect of this overexpression?

a. Inhibitionofhexokinasebybuilt-upglucose6-phosphate
b. Activationofphosphofructokinasebyfructose2,6-bisphosphate c. Enhancedfluxthroughgluconeogenesis
d. Reduced flux through the citric acid cycle.

The correct answer is b. Overexpression of phosphoglucose isomerase will lead to higher levels of fructose 6-phosphate, which can be converted to fructose 2,6-bisphosphate. F-2,6-BP is an allosteric activator of PFK.