As suggested by the name, the light-independent reaction occurs without the precence of light. To start, carbon dioxide combines with ribulose bisphosphate (RuBP) to produce two molecules of glycerate 3-phosphate (GP). From this, the GP is reduced to triose phosphate (TP) with the help of NADPH, or reduced NADP (a co-factor), and energy in the form of ATP. Triose phospahe is then converted to glucose, which is an organic susbtance.