Correct option is A
Succinate and citrate are intermediates of the citric acid cycle but do not directly serve as carbon skeletons for amino acid synthesis. Key intermediates such as α-ketoglutarate and oxaloacetate provide carbon skeletons for glutamate, aspartate, and other amino acids. Similarly, 3-phosphoglycerate and phosphoenolpyruvate are glycolytic intermediates contributing to amino acid biosynthesis. Ribose 5-phosphate and erythrose 4-phosphate are part of the pentose phosphate pathway, aiding in synthesizing aromatic amino acids.
Information Booster:
1. Succinate and citrate are involved in the TCA cycle but do not contribute directly to amino acid synthesis.
2. 3-phosphoglycerate and phosphoenolpyruvate are precursors for serine, glycine, and cysteine.
3. Ribose 5-phosphate and erythrose 4-phosphate are precursors for aromatic amino acids (phenylalanine, tyrosine, and tryptophan).
4. α-ketoglutarate is the precursor for glutamate and proline synthesis.
5. Oxaloacetate is the precursor for aspartate, which further gives rise to asparagine, methionine, lysine, and threonine. Amino acid synthesis relies on specific intermediates from glycolysis, the TCA cycle, and the pentose phosphate pathway.
6. The integration of metabolic pathways is essential for biosynthesis and energy regulation.
Additional Knowledge:
Succinate and citrate: While crucial for energy metabolism in the citric acid cycle, these intermediates do not directly provide carbon skeletons for amino acid synthesis.
3-phosphoglycerate and phosphoenolpyruvate: Derived from glycolysis, these intermediates form amino acids like serine, glycine, and cysteine. Phosphoenolpyruvate (PEP) also contributes to the synthesis of aromatic amino acids via the shikimate pathway in plants and microorganisms.
Ribose 5-phosphate and erythrose 4-phosphate :Products of the pentose phosphate pathway, these serve as precursors for aromatic amino acids (phenylalanine, tyrosine, and tryptophan) via the shikimate pathway in plants and some microorganisms.
α-ketoglutarate and oxaloacetate: These are primary precursors in the TCA cycle for synthesizing amino acids such as glutamate (from α-ketoglutarate) and aspartate (from oxaloacetate).
