The Calvin Cycle Basics
Ever wonder how plants turn air into food? That's exactly what the Calvin Cycle does! It's essentially a sugar factory that takes the ATP and NADPH produced during light reactions and combines them with carbon dioxide from the air to create sugars.
The Calvin Cycle is called a cycle because the starting materials get recycled and used again. It's an efficient system where most molecules stay in the loop while only a small portion becomes the actual sugar product.
Step One: Carbon Fixation involves an enzyme called Rubisco that combines CO₂ with a 5-carbon sugar called RuBP. This forms an unstable 6-carbon compound that quickly splits into two 3-carbon sugars called 3-PGA. For every three CO₂ molecules, you get six 3-PGA molecules.
Step Two: Reduction transforms these 3-PGA molecules using energy from ATP and NADPH. Six ATP molecules convert to ADP+P, and six NADPH convert to NADP⁺. This creates high-energy 3-carbon compounds called G3P.
Quick Tip: Think of Rubisco as a "carbon catcher" - it's actually the most abundant protein on Earth because plants need so much of it to grab carbon dioxide from the air!
