A Nearly Universal Metabolic Pathway in Which the Acetyl Group of Acetyl Coenzyme a Is Effectively Oxidized to Two Co2 and Four Pairs of Electrons Are Transferred to Coenzymes. the Acetyl Group Combines with Oxaloacetate to Form Citrate Which Undergoes Successive Transformations to Isocitrate 2 Oxoglutarate Succinyl Coa Succinate Fumarate Malate and Oxaloacetate Again Thus Completing the Cycle. in Eukaryotes the Tricarboxylic Acid Is Confined to the Mitochondria. See Also Glyoxylate Cycle.
The Chemical Reactions and Pathways Including Anabolism and Catabolism by Which Living Organisms Transform Chemical Substances. Metabolic Processes Typically Transform Small Molecules But Also Include Macromolecular Processes Such As DNA Repair and Replication and Protein Synthesis and Degradation.
The Combination of Atmospheric Co2 with a 3 Carbon Molecule Phosphoenol Pyruvate (pep) in the Mesophyll Cells to Make a 4 Carbon Acid Which Is Immediately Converted to Malic Acid. the Malic Acid Is Then Passed Across to the Bundle Sheath Cells Where It Is Broken Down Again to Pyruvic Acid and Co2. the Acid Is Passed Back to the Mesophyll Cells to Be Used Again While the Co2 Is Fed Into the Reductive Pentose Phosphate Cycle (calvin Cycle) and Converted Into Sugar and Starch.
Catalysis of a Biochemical Reaction At Physiological Temperatures. in Biologically Catalyzed Reactions the Reactants Are Known As Substrates and the Catalysts Are Naturally Occurring Macromolecular Substances Known As Enzymes. Enzymes Possess Specific Binding Sites For Substrates and Are Usually Composed Wholly or Largely of Protein But RNA That Has Catalytic Activity (ribozyme) Is Often Also Regarded As Enzymatic.
Catalysis of the Cleavage of C C C O C N and Other Bonds by Other Means Than by Hydrolysis or Oxidation or Conversely Adding a Group to a Double Bond. They Differ From Other Enzymes in That Two Substrates Are Involved in One Reaction Direction But Only One in the Other Direction. When Acting On the Single Substrate a Molecule Is Eliminated and This Generates Either a New Double Bond or a New Ring.