Which of the following metabolic pathway in carbohydrate metabolism is required for synthesis of nucleic acids –
**Core Concept**
The question is testing the knowledge of the metabolic pathways involved in carbohydrate metabolism, specifically those that are required for the synthesis of nucleic acids. The correct answer involves the conversion of glucose to a key intermediate that serves as a precursor for nucleotide synthesis.
**Why the Correct Answer is Right**
The correct answer is the pentose phosphate pathway (PPP). This pathway is essential for the synthesis of nucleic acids as it generates ribose-5-phosphate, a precursor for the synthesis of nucleotides. The PPP is a non-oxidative pathway that converts glucose-6-phosphate into ribose-5-phosphate, which is then used to synthesize nucleotides, such as ATP, GTP, CTP, and UTP. This pathway is also crucial for the synthesis of NADPH, which is required for various anabolic reactions, including fatty acid synthesis and cholesterol synthesis.
**Why Each Wrong Option is Incorrect**
* **Option A:** Glycolysis is the first step in glucose metabolism and generates pyruvate, but it does not directly contribute to nucleic acid synthesis.
* **Option B:** The citric acid cycle is a key pathway in cellular respiration and generates ATP, NADH, and FADH2, but it is not directly involved in nucleic acid synthesis.
* **Option D:** Gluconeogenesis is the process of generating glucose from non-carbohydrate sources and is not directly involved in nucleic acid synthesis.
**Clinical Pearl / High-Yield Fact**
The pentose phosphate pathway is also involved in the synthesis of NADPH, which is required for the reduction of oxidized glutathione, a key antioxidant in the cell.
**Correct Answer:** C. The pentose phosphate pathway