Glucose produced during photosynthesis contains energy absorbed from sunlight. The energy released from the breakdown of glucose is used to synthesise ATP, mostly by a process called chemiosmosis. A small amount of ATP is made directly by substrate-level phosphorylation, for example in glycolysis.Respiration is a multi-step pathway with enzymes catalysing each of the reactions. In the cell, the processes are continuous, but the first stage of respiration is called glycolysis.Glycolysis is an anaerobic process of 10 enzyme-catalysed reactions which occurs in the cytoplasm. Glucose is split into 2 pyruvate molecules and ATP and reduced nicotinamide adenine dinucleotide (NAD) are formed.