Kaplan Nursing Entrance Practice Exam

Where does the Krebs cycle take place within a cell?

1. Cytoplasm

2. Nucleus

3. Mitochondrion

4. Endoplasmic Reticulum

The correct answer is: Mitochondrion

The Krebs cycle, also known as the citric acid cycle or tricarboxylic acid cycle, occurs within the mitochondrion of a cell. This organelle is often referred to as the powerhouse of the cell due to its critical role in energy production. The Krebs cycle is essential for the aerobic respiration process, where it generates energy in the form of ATP through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. Mitochondria contain the necessary enzymes and substrates required for the various reactions of the Krebs cycle, facilitating the conversion of energy stored in food into a usable form for cellular processes. The products of the Krebs cycle, including NADH and FADH2, are then utilized in the electron transport chain, which further generates ATP. While other cellular components such as the cytoplasm, nucleus, and endoplasmic reticulum serve important functions, they are not involved in the Krebs cycle. The cytoplasm is primarily the site of glycolysis and other metabolic pathways, the nucleus houses genetic material, and the endoplasmic reticulum is involved in the synthesis of proteins and lipids but does not play a direct role in the Krebs cycle. Thus, the mitochondrial location is key to its function in cellular