Step 6 of Glycolysis i. The energy of 1,3-BPG is trapped to synthesize one ATP molecule with the help of bisphospho glycerate kinase. ii. This is an example of substrate-level phosphorylation, where energy is trapped directly from the substrate, without the help of the complicated electron transpo chain reactions. iii. When energy is trapped by oxidation of reducing equivalents such as NADH, it is called oxidative phosphorylation. Step 6 is reversible. Since reversal of this reaction occurs in gluconeogenesis.Ref: DM Vasudevan, 7th edition, page no: 110