NANP Board Practice Exam

Where does the Krebs Cycle take place?

1. Cytoplasm

2. Mitochondrial matrix

3. Nucleus

4. Rough Endoplasmic Reticulum

The correct answer is: Mitochondrial matrix

The Krebs Cycle, also known as the citric acid cycle or tricarboxylic acid (TCA) cycle, occurs in the mitochondrial matrix. This is the innermost compartment of the mitochondria, which is where the reactions of the Krebs Cycle take place, allowing for the efficient production of energy. The mitochondria are often referred to as the powerhouse of the cell because they generate ATP, the energy currency of the cell, through this cycle. The other options represent cellular components where different processes occur: the cytoplasm is where glycolysis and other metabolic processes take place, the nucleus houses genetic material and is involved in transcription and replication, and the rough endoplasmic reticulum is primarily involved in protein synthesis and folding. Each of these locations has distinct functions that do not pertain to the Krebs Cycle, further emphasizing the uniqueness of the mitochondrial matrix in energy metabolism.