D. ATP molecules are produced in photosynthesis and used up in respiration. Answer in the space provided. Glycolysis and gluconeogenesis are two opposing pathways for the breakdown and synthesis of glucose, respectively. Describe the general mechanisms that are used to regulate these two processes. Circulating hormones such as insulin and epinephrine activate susceptible cells to undergo either glycolysis or gluconeogenesis, depending on the needs of the organism.
Allosteric regulation affects the two pathways in individual cells.
While most enzymes are common to the two pathways, several key regulatory enzymes are unique to each. In glycolysis, ATP synthesis occurs by substrate-level phosphorylation. ATP is supplied by high-energy phosphate bonds in chemical intermediates of glycolysis, such as phosphoenol pyruvate. In respiration, ATP synthesis occurs by oxidative phosphorylation. The energy for the ATP synthesis reaction comes from the potential energy of the proton gradient formed by electron transport.