Calvin cycle

Photosynthesis consists of two stages.

There are the so-called light reactions, in which solar energy is converted into chemical energy, and then there's the Calvin cycle, which uses that chemical energy to build G3P, the precursor to glucose and other molecules.

Both of these stages occur inside one of the organelles found in plant cells, which are called chloroplasts, and there are around 30 to 40 of them per cell.

A chloroplast has two membranes that surround a fluid called stroma, within which sacs called thylakoids are suspended.

But instead of producing ATP, photosystem I will result in the conversion of nicotinamide adenine dinucleotide phosphate, or NADP+, into NADPH.

So the light reactions in the thylakoid, which are summarized by the following equations, require sunlight and water among the reactants and generate oxygen, ATP, and NADPH as products.

ATP and NADPH are then used in the Calvin cycle, which occurs in the stroma.

This is where all the synthesis occurs.

The oxygen is released as a byproduct, which is why photosynthesis is the primary source of oxygen in the Earth's atmosphere.

The ATP and electron carriers produced in the light-dependent reactions are then used in the second stage, the light-independent reactions, also known as the Calvin cycle.

Now, the Calvin cycle depends on the products of the light reactions.

So in this cycle, carbon dioxide is fixed, meaning inorganic carbon dioxide gas is used to build the backbones of organic molecules.

An enzyme called Rubisco, this is probably my favorite enzyme name, helps combine carbon dioxide with a 5-carbon molecule, eventually leading to the production of glucose and other carbohydrates.