Cancer cells derive energy from –
**Core Concept**
Tumors exhibit altered metabolism, a phenomenon known as the Warburg effect, where cancer cells preferentially utilize glycolysis for energy production even in the presence of adequate oxygen. This results in increased glucose uptake and lactate production.
**Why the Correct Answer is Right**
The Warburg effect is characterized by an overexpression of glycolytic enzymes, particularly hexokinase, which facilitates the conversion of glucose to glucose-6-phosphate. This process bypasses the normal oxidative phosphorylation pathway, allowing cancer cells to maintain high energy production and biomass synthesis. The lactate produced as a byproduct of glycolysis is then used to promote tumor growth and invasion.
**Why Each Wrong Option is Incorrect**
**Option A:** Aerobic respiration is the normal metabolic pathway for energy production in healthy cells, where glucose is converted to carbon dioxide and water with the generation of ATP. However, cancer cells preferentially use glycolysis for energy production.
**Option B:** Fatty acid oxidation is an alternative energy source, but it is not the primary mechanism by which cancer cells derive energy. In fact, cancer cells often have impaired fatty acid oxidation due to genetic mutations.
**Option C:** Gluconeogenesis is the process by which glucose is synthesized from non-carbohydrate sources, such as lactate or amino acids. While gluconeogenesis can occur in cancer cells, it is not the primary mechanism by which they derive energy.
**Clinical Pearl / High-Yield Fact**
The Warburg effect is a hallmark of cancer metabolism, and targeting glycolytic enzymes or the lactate transporter MCT1 has shown promise in cancer therapy.
**Correct Answer: A. Glycolysis**