Source of ATP in RBC&;s is
**Core Concept**
The question is testing the ability to recall the unique metabolic characteristics of red blood cells (RBCs). RBCs lack mitochondria and therefore cannot generate ATP through oxidative phosphorylation. As a result, they rely on glycolysis to produce ATP.
**Why the Correct Answer is Right**
In RBCs, the enzyme glyceraldehyde-3-phosphate dehydrogenase is responsible for converting glyceraldehyde-3-phosphate into 1,3-bisphosphoglycerate, generating NADH in the process. The NADH is then used to produce ATP through substrate-level phosphorylation in the glycolytic pathway. This is the primary mechanism by which RBCs produce ATP.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the production of ATP in RBCs.
* **Option B:** This option is incorrect because RBCs do not have mitochondria to generate ATP through oxidative phosphorylation.
* **Option D:** This option is incorrect because, although RBCs do have some ATP production through the pentose phosphate pathway, it is not the primary source of ATP.
**Clinical Pearl / High-Yield Fact**
RBCs have a unique metabolic profile that allows them to maintain their function for several months without mitochondria. This is due to the presence of specific enzymes that enable glycolysis to produce ATP, as well as the ability to store and release ATP through various mechanisms.
**Correct Answer:** C. Glycolysis.