Calvin cycle

What is calvin cycle?

The Calvin cycle is the second stage of photosynthesis, happening in the chloroplast stroma. It uses ATP and NADPH (from the light-dependent reactions) to fix carbon dioxide into glyceraldehyde-3-phosphate (G3P), eventually producing glucose. Three phases: CO₂ fixation (catalysed by RuBisCO), reduction (G3P from GP using ATP + NADPH), and regeneration of ribulose bisphosphate (RuBP). Named after Melvin Calvin (1961 Nobel Prize). Independent of light directly, but stops when ATP/NADPH run out.