Source of ribose is
**Core Concept**
Ribose is a pentose sugar that serves as a fundamental building block for various biomolecules, including nucleic acids (DNA and RNA), ATP, and NADH. It is a crucial component of the molecular structure of these molecules, playing a vital role in their synthesis and function. The question is testing the student's knowledge of the biosynthetic pathway of ribose.
**Why the Correct Answer is Right**
The correct answer is that ribose is synthesized from glucose via the pentose phosphate pathway. This process involves the conversion of glucose-6-phosphate into ribose-5-phosphate through a series of enzyme-catalyzed reactions. The key enzymes involved in this pathway are glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and ribose-5-phosphate isomerase. The pentose phosphate pathway is an essential metabolic pathway that generates NADPH and ribose-5-phosphate, which are used in various biosynthetic reactions.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct source of ribose. While glucose is a precursor to ribose, this option is too vague.
**Option B:** This option is incorrect because it refers to the breakdown of ribose, rather than its synthesis.
**Option C:** This option is incorrect because it does not accurately describe the biosynthetic pathway of ribose.
**Clinical Pearl / High-Yield Fact**
The pentose phosphate pathway is an essential metabolic pathway that generates NADPH, which is used in various biosynthetic reactions, including the synthesis of fatty acids and cholesterol. This pathway is also involved in the regulation of glucose metabolism and the generation of reactive oxygen species.
**Correct Answer: D. Glucose via the pentose phosphate pathway**