Pigments - photosyn

Light-dependent Reaction

The part of photosynthesis that occurs in the presence of solar energy and involves the absorption of light by pigments to generate ATP and NADPH.

Photosynthesis

The process by which autotrophs convert solar energy into chemical energy, occurring in the chloroplasts.

Light absorption

The process by which chlorophyll absorbs light energy, exciting electrons and causing them to move to a higher energy level.

Photosystem II

A protein complex embedded in the thylakoid membrane that absorbs light energy and uses it to split water molecules into oxygen, protons, and electrons.

Electron transport chain

A series of electron carriers through which excited electrons move, releasing energy that is used to pump protons across the thylakoid membrane.

Photosystem I

Another protein complex embedded in the thylakoid membrane that absorbs light energy and uses it to boost the energy of electrons, which are then used to reduce NADP+ to NADPH.

Proton gradient

The accumulation of protons on the inside of the thylakoid membrane, created by the electron transport chain, which is used by ATP synthase to generate ATP.

Photolysis of water

The process of splitting water molecules into oxygen, protons, and electrons to replenish the electrons lost in the light-dependent reactions and reduce NADP+ to NADPH.

Chloroplast

The organelle that houses the components involved in photosynthesis, consisting of a double-membrane structure and containing the stroma, grana, and thylakoids.

Stroma

The fluid-filled space within the chloroplast that surrounds the thylakoids and contains enzymes and proteins involved in the Calvin cycle.

Grana

Stacks of flattened, sac-like structures called thylakoids, where the light-dependent reactions of photosynthesis take place.

Thylakoids

Membranous sacs that make up the grana and contain chlorophyll and other proteins involved in light-dependent reactions.

Carbon fixation (RuBisCO activation)

The first step of the Calvin cycle, in which carbon dioxide is attached to a five-carbon molecule called ribulose-1,5-bisphosphate (RuBP) by the enzyme RuBisCO, forming two molecules of 3-phosphoglycerate (3PGA).

Reduction

The conversion of two molecules of 3PGA into two molecules of glyceraldehyde 3-phosphate (G3P) using ATP and NADPH.

Regeneration

The process of regenerating some of the G3P molecules to form RuBP, allowing the Calvin cycle to continue, and requiring ATP.

Requirements for Glucose (C₆H₁₂O₆)

The quantities of 18 ATP, 12 NADPH, 6 CO2, 6 RUBP, and 2 G3P needed for the synthesis of one molecule of glucose.

ATP Needed for one Glucose

18

NADPH Needed for one Glucose

12

CO2 and RUBP Needed for one Glucose

6

G3P Needed for one Glucose

2