Download Guidelines to the Citric acid cycle

Lecturer Dr BS Wilhelmi May 2010
The Citric Acid Cycle
REFERENCES
Voet and Voet, Chapter 21, p 765
Mathews and Von Holde, Chapter 14, p 467
Garrett and Grisham, Chapter 20, p 639
AIM
An introduction to the reactions, regulation and function of the citric acid cycle.
PURPOSE
The citric acid cycle is a series of reactions, which forms the central hub of the
metabolic system. It accounts for the major portion of carbohydrate, fatty acid and
amino acid metabolism, and it also generates numerous biosynthetic precursor
molecules.
OUTCOMES
The student must be able to:
1. List the reaction sequences of the citric acid cycle, complete with structures,
names of structures, enzyme names and cofactors involved in the cycle.
2. Explain the regulation of the citric acid cycle.
3. Explain the mechanism of the action of the pyruvate and -ketoglutarate
complexes dehydrogenase multi-enzyme complexes.
4. Explain the cataplerotic and anaplerotic nature of the citric acid cycle.
KEY CONCEPTS
Oxidation of the acetyl group of acetyl-CoA, pyruvate dehydrogenase multi-enzyme
complex, product inhibition, oxidative phosphorylation, substrate availability, rate
controlling enzymes.
SELF EVALUATION
1. Explain all key concepts.
2. Summarise the events of one turn of the citric acid cycle.
3. Describe the reaction mechanism of the pyruvate dehydrogenase and
ketoglutarate complexes.
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4. Explain what is meant by the 'cataplerotic and anaplerotic nature' of the citric acid
cycle under the following headings:
4.1 The biosynthetic roles of the citric acid cycle intermediates (use a diagram).
4.2 Examples of reactions that replenish the citric acid cycle
intermediates.