photosythesis terms

Absorption Spectrum

The range of a pigment’s ability to absorb various wavelengths of light.

Accessory Pigment

Pigments that absorb light at different wavelengths than chlorophyll and pass the energy to chlorophyll for photosynthesis.

Anoxygenic Photosynthesis

Photosynthesis that does not produce oxygen, occurring in certain bacteria that use electron donors other than water.

Antenna Complex

A complex of pigments that captures light energy and transfers it to the reaction center in photosynthesis.

ATP Synthase

An enzyme that creates ATP from ADP and inorganic phosphate during chemiosmosis in the mitochondria and chloroplasts.

CAM Plants

Plants that use crassulacean acid metabolism (CAM) to fix carbon, adapted to dry environments by opening stomata at night to reduce water loss.

C3 Photosynthesis

The most common form of photosynthesis, where the Calvin cycle fixes carbon dioxide into a 3-carbon compound.

C3 Plants

Plants that use C3 photosynthesis, fixing carbon dioxide into a 3-carbon compound in the Calvin cycle.

C4 Plants

Plants that use a modified form of photosynthesis where carbon dioxide is initially fixed into a 4-carbon compound to minimize photorespiration.

Calvin Cycle

The cycle of reactions in photosynthesis that uses ATP and NADPH to convert CO₂ into sugars.

Carbon Fixation

The process of converting inorganic carbon (CO₂) into an organic form (sugar) during photosynthesis.

Carotenoids

Pigments that absorb excess light energy and protect chlorophyll from damage, such as β-carotene.

Charge Separation

The movement of an excited electron to a higher energy state in photosynthesis, initiating the electron transport chain.

Chemiosmosis

The movement of protons across a membrane to generate ATP, driven by the energy from the electron transport chain.

Chlorophyll

The green pigment found in the chloroplasts of plants that captures light energy for photosynthesis.

Chlorophyll a

The primary type of chlorophyll that absorbs light for photosynthesis, with absorption peaks in the violet-blue and red parts of the spectrum.

Chlorophyll b

An accessory pigment that helps chlorophyll a capture additional light energy by absorbing blue and red-orange light.

Cyclic Photophosphorylation

A type of photosynthesis where the electron transport chain produces ATP but no NADPH or oxygen.

Cytochrome b6-f Complex

A protein complex in the thylakoid membrane that transfers electrons from plastoquinone to plastocyanin in photosynthesis.

Electron Transport

The movement of electrons through a series of proteins and other molecules to produce energy in the form of ATP or NADPH.

Ferredoxin

A protein that transfers electrons to NADP+ to form NADPH during the light reactions of photosynthesis.

Light-Dependent Reactions

The reactions of photosynthesis that require light, producing ATP and NADPH.

Light-Independent Reactions

The reactions of photosynthesis that do not require light and use ATP and NADPH to convert CO₂ into sugars.

Glyceraldehyde 3-Phosphate (G3P)

A 3-carbon sugar formed in the Calvin cycle and used to synthesize glucose and other organic compounds.

Grana

Stacks of thylakoids in the chloroplast where the light-dependent reactions of photosynthesis occur.

NADP+

A coenzyme that carries electrons during the light reactions of photosynthesis, later reduced to form NADPH.

NADP Reductase

An enzyme in the thylakoid membrane that reduces NADP+ to NADPH during the light-dependent reactions of photosynthesis.

NADPH

The reduced form of NADP+, which carries electrons and is used in the Calvin cycle to help produce sugars.

Non-Cyclic Photophosphorylation

A process in photosynthesis where both ATP and NADPH are produced, and oxygen is released as a byproduct.

Oxygenic Photosynthesis

Photosynthesis that produces oxygen as a byproduct, occurring in plants, algae, and cyanobacteria.

Pigments

Molecules that absorb light at specific wavelengths and play a role in capturing energy for photosynthesis.

Phosphoenolpyruvate (PEP)

A 3-carbon compound involved in the carbon fixation process in C4 and CAM plants.

3-Phosphoglycerate (PGA)

A 3-carbon molecule formed in the Calvin cycle after CO₂ is fixed by rubisco.

Photoelectric Effect

The emission of electrons from a material when it absorbs light energy.

Photon

A particle of light energy that can excite electrons during the light-dependent reactions of photosynthesis.

Photorespiration:

Photosynthesis

• Definition: The process by which plants, algae, and some bacteria use light energy, CO₂, and water to produce glucose and oxygen.

• Term: Phycobiliproteins

• Definition: Pigments in cyanobacteria and red algae that absorb light and pass the energy to chlorophyll for photosynthesis.

• Term: Plastocyanin

• Definition: A copper-containing protein in the electron transport chain of photosynthesis that transfers electrons to photosystem I.

• Term: Plastoquinone

• Definition: A molecule in the electron transport chain that transfers electrons from photosystem II to cytochrome b6-f complex.

• Term: Porphyrin Ring

• Definition: A ring-shaped structure in chlorophyll that plays a central role in capturing light energy during photosynthesis.

• Term: Proton Gradient

• Definition: The concentration difference of protons (H⁺ ions) across a membrane, which drives the synthesis of ATP.

• Term: Primary Photoevent

• Definition: The initial event in photosynthesis where a photon is absorbed, exciting an electron in a pigment molecule.

• Term: Reaction Center

• Definition: The complex in a photosystem where energy from absorbed light is used to excite electrons, initiating electron transport.

Reduction

• Definition: The gain of electrons by a molecule during a chemical reaction, often accompanied by the gain of energy.