Photosynthesis

Photosynthesis

The process by which light energy is converted to chemical energy.

Chemical equation of photosynthesis

6CO2 + 6H2O → C6H12O6 + 6O2, representing raw materials used to manufacture sugars.

Prokaryotic photosynthesis

Early photosynthesis that contributed to atmospheric oxygen production and laid the foundation for eukaryotic photosynthesis.

Light reactions

Also called light-dependent reactions; they use light energy to produce ATP and NADPH.

Dark reactions

Also called light-independent reactions; they use ATP and NADPH to convert CO2 into carbohydrates.

Chloroplast

Organelles in plant cells where photosynthesis occurs.

Stroma

The fluid-filled region inside a chloroplast where the dark reactions take place.

Grana

Stacks of thylakoids within the chloroplast.

Thylakoids

Disc-like structures within the grana that contain chlorophyll and enzymes involved in photosynthesis.

Chlorophyll

A light-absorbing pigment that drives the process of photosynthesis.

Antenna complexes

Groups of pigments that gather light energy and transfer it to the reaction center.

Photosystem I (PS I) and Photosystem II (PS II)

Two types of reaction centers that use different types of chlorophyll.

Photolysis

The process of splitting water into oxygen, hydrogen ions, and electrons to replenish those lost in photosystem II.

Proton gradient

Established when hydrogen ions are pumped into the thylakoid lumen, driving ATP production.

NADP+

The final electron acceptor that is reduced to NADPH in photosystem I.

Calvin-Benson Cycle

The light-independent reactions where CO2 is fixed into carbohydrates.

CAM plants

Plants that temporally separate carbon fixation and the Calvin cycle by opening stomata at night.

C4 plants

Plants with specialized leaf anatomy that fix CO2 in a different part of the leaf to reduce photorespiration.