photosynthesis in higher plants

Photosynthesis

The biological process in which plants use light energy from the sun to fuel the formation of organic molecules like glucose.

Autotrophs

Organisms, such as plants, that can produce their own food through photosynthesis.

Heterotrophs

Organisms, such as humans, that depend on other organisms, particularly green plants, for nutrition.

Chlorophyll

The green pigment found in leaves that is responsible for capturing light energy during photosynthesis.

Light reactions

The set of reactions in photosynthesis that capture solar energy and produce ATP and NADPH.

Dark reactions

The set of reactions in photosynthesis that use ATP and NADPH to convert CO2 into sugar.

Pigments

Molecules, such as chlorophyll-a, chlorophyll-b, xanthophylls, and carotenoids, that absorb light energy during photosynthesis.

Light-harvesting complexes (LHC)

Complexes of pigments in photosystems that capture and transfer light energy.

Photosystem-1 (PSI)

The photosystem in photosynthesis that has a maximum absorption at 700 nm and is involved in the production of NADPH.

Photosystem-2 (PSII)

The photosystem in photosynthesis that has a maximum absorption at 680 nm and is involved in the splitting of water and the production of ATP.

Electron transport system

The system in photosynthesis that transfers electrons from PSII to PSI, resulting in the production of ATP and NADPH.

Z scheme

The name given to the electron transport system in photosynthesis.

Cyclic photophosphorylation

The process in photosynthesis where only PSI is active, and ATP is synthesized through a cyclic flow of electrons.

Non-cyclic photophosphorylation

The process in photosynthesis where both PSII and PSI act in series, resulting in the synthesis of both ATP and NADPH.

Chemiosmosis hypothesis

The hypothesis that proposes that ATP synthesis in photosynthesis is driven by a flow of protons across a membrane.

Chemiosmosis

The process in which ATP is synthesized using the energy from a proton gradient across a membrane.

ATP synthase

An enzyme composed of two parts (F0 and F1) that synthesizes ATP using the energy from the proton gradient.

Thylakoid

A membrane-bound compartment inside chloroplasts where the light-dependent reactions of photosynthesis occur.

Dark reaction

The biosynthetic phase of photosynthesis where ATP and NADPH are used to synthesize food.

C3 pathway or Calvin cycle

The pathway in which the first stable product of carbon fixation is a three-carbon molecule called PGA (Phosphoglyceric acid).

C4 pathway or Hatch-Slack pathway

The pathway in which the first stable product of carbon fixation is a four-carbon molecule called OAA (Oxaloacetate).

RuBisCO

The most abundant enzyme on the planet that binds both CO2 and O2, and is involved in carbon fixation.

Photorespiration

A wasteful process that occurs in C3 plants when some O2 binds with RuBisCO, leading to the formation of phosphoglycerate and phosphoglycolate.

Limiting factor

The factor that determines the rate of a chemical process when multiple factors are affecting it.

Light reaction

The stage of photosynthesis where light energy is absorbed by pigments and converted into chemical energy in the form of ATP and NADPH.

ATP

Adenosine Triphosphate, a molecule that stores and releases energy for cellular processes.

NADPH

Nicotinamide Adenine Dinucleotide Phosphate, a molecule that carries high-energy electrons used in photosynthesis.

Light reaction

The first stage of photosynthesis where light energy is converted into chemical energy in the form of ATP and NADPH.

RuBisCO

Ribulose-1,5-bisphosphate carboxylase/oxygenase, an enzyme involved in the fixation of carbon dioxide during photosynthesis.

Photorespiration

An inefficient oxygenation reaction catalyzed by RuBisCO in C3 plants.

C3 plants

Plants that use the Calvin pathway for carbon fixation and produce a 3-carbon compound as the first stable product.

C4 pathway

A type of photosynthesis found in some tropical plants where the first stable product of CO2 fixation is a 4-carbon compound.