Final answer:
Bacteria may use the Entner-Doudoroff (ED) pathway and the pentose phosphate pathway (PPP) simultaneously, with the PPP being used for nucleotide and amino acid biosynthesis and the ED pathway providing alternative fermentation products during glycolysis.
Step-by-step explanation:
Organisms, specifically bacteria, may utilize different pathways for glycolysis based on their metabolic needs. The Entner-Doudoroff (ED) pathway is an alternative to the well-known Embden-Meyerhof-Parnas (EMP) pathway and is predominantly used by certain bacteria like Pseudomonas aeruginosa.
Unlike organisms that use EMP for glycolysis, organisms with the ED pathway produce different fermentation products such as pyruvate, ethanol, and/or acetic acid, along with CO₂.
Simultaneously, organisms may utilize the pentose phosphate pathway (PPP), which operates in parallel to glycolysis, generating NADPH and five-carbon sugars. The PPP is crucial for the production of ribose 5-phosphate, a precursor for nucleotide synthesis, and is also essential for fatty acid and amino acid biosynthesis.
Therefore, the utilization of ED and PPP pathways allows the organism to flexibly manage energy production with the biosynthetic requirements for nucleic acids and proteins.
Organisms will favor the PPP for glycolysis when a greater need for nucleic acid and protein synthesis exists, given the role of PPP intermediates in these biosynthesis processes. This demonstrates a strategic adaptation where metabolic pathways are engaged depending on the cellular demands.