Updated Photosynthesis 54 terms

Absorption spectrum

The range of wavelengths of light absorbed by a pigment, such as chlorophyll, during photosynthesis.

Accessory pigment

A pigment that assists in photosynthesis by capturing additional light wavelengths that chlorophyll cannot absorb.

Anoxygenic photosynthesis

A form of photosynthesis that does not produce oxygen, typically found in certain bacteria.

Antenna complex

A collection of pigment molecules that gather photons and pass the energy to the reaction center in a photosystem.

ATP Synthase

An enzyme in the thylakoid membrane that produces ATP from ADP and inorganic phosphate using the proton gradient.

CAM plants

Plants that fix carbon at night using crassulacean acid metabolism, minimizing water loss by opening stomata at night.

C3 photosynthesis

The most common form of photosynthesis, where CO2 is initially fixed into a three-carbon compound.

C3 plants

Plants that use the C3 pathway for carbon fixation, which is most efficient under cool, moist conditions.

C4 plants

Plants that fix CO2 into a four-carbon compound as part of a process that reduces photorespiration, typically adapted to hot, dry environments.

Calvin cycle

The cycle of reactions that take place in the stroma of chloroplasts during photosynthesis, where carbon fixation occurs and glucose is produced.

Carbon fixation

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

Carotenoids

Accessory pigments that absorb blue and green light and reflect yellow, orange, or red, aiding in photosynthesis.

Charge separation

The process in photosynthesis where excited electrons are transferred from the reaction center to an acceptor molecule.

Chemiosmosis

The process by which the movement of protons across a membrane drives the production of ATP.

Chlorophyll

The green pigment that captures light energy for photosynthesis.

Chlorophyll a

The primary pigment in photosynthesis that absorbs light mainly in the blue and red wavelengths.

Chlorophyll b

An accessory pigment that broadens the range of light a plant can use for photosynthesis by absorbing light in the blue and orange wavelengths.

Cyclic photophosphorylation

A process in photosynthesis where electrons are cycled back to the photosystem, generating ATP without producing NADPH or oxygen.

Cytochrome b6-f complex

A component of the electron transport chain in the thylakoid membrane that pumps protons across the membrane to create a proton gradient.

Electron transport

The movement of electrons through a series of protein complexes in the thylakoid membrane to create an electrochemical gradient.

Ferredoxin

An iron-sulfur protein that acts as an electron carrier in photosynthesis, transferring electrons to NADP+ reductase.

Light-dependent reactions

The set of reactions in photosynthesis that convert light energy into chemical energy in the form of ATP and NADPH.

Light-independent reactions

Reactions that do not require light, such as the Calvin cycle, where ATP and NADPH produced in the light-dependent reactions are used to fix carbon into sugars.

Glyceraldehyde 3-phosphate (G3P)

A three-carbon sugar produced in the Calvin cycle that can be used to form glucose and other carbohydrates.

Grana

Stacks of thylakoid membranes within the chloroplasts where light-dependent reactions of photosynthesis take place.

NADP+

An electron carrier that is reduced to NADPH during the light-dependent reactions of photosynthesis.

NADP reductase

The enzyme that catalyzes the transfer of electrons from ferredoxin to NADP+, forming NADPH.

NADPH

The reduced form of NADP+ that carries electrons and hydrogen ions for use in the Calvin cycle during photosynthesis.

Non-cyclic photophosphorylation

The process in photosynthesis where electrons move linearly through the electron transport chain, resulting in the production of both ATP and NADPH.

Oxygenic photosynthesis

Photosynthesis that produces oxygen, as seen in plants, algae, and cyanobacteria.

Pigments

Molecules that absorb certain wavelengths of light and reflect others, used by plants to capture light energy for photosynthesis.

Phosphoenolpyruvate (PEP)

A three-carbon molecule involved in the C4 photosynthetic pathway as an intermediate for carbon fixation.

3-phosphoglycerate (PGA)

A three-carbon compound formed in the Calvin cycle during the fixation of CO2.

Photoelectric effect

The process by which light energy excites electrons, causing them to move to a higher energy state.

Photon

A particle of light that carries energy, which can excite electrons in pigments during photosynthesis.

Photorespiration

A wasteful process in plants where oxygen is fixed instead of carbon dioxide by rubisco, reducing the efficiency of photosynthesis.

Photosystem I

The second photosystem in the electron transport chain of photosynthesis that absorbs light to excite electrons for NADPH production.

Photosystem II

The first photosystem in the electron transport chain of photosynthesis that absorbs light, initiating the electron transport chain and splitting water molecules.

Photosynthesis

The process by which plants, algae, and some bacteria convert light energy, water, and carbon dioxide into glucose and oxygen.

Phycobiliproteins

Accessory pigments found in cyanobacteria and red algae that help capture light energy for photosynthesis.

Plastocyanin

A copper-containing protein that transfers electrons between the cytochrome b6-f complex and photosystem I.

Plastoquinone

An electron carrier in the thylakoid membrane that transfers electrons between photosystem II and the cytochrome b6-f complex.

Porphyrin ring

The light-absorbing part of the chlorophyll molecule, responsible for capturing light energy during photosynthesis.

Proton gradient

A difference in proton concentration across a membrane, which powers ATP synthesis during photosynthesis.

Primary photoevent

The initial absorption of light by pigments in photosystems, resulting in the excitation of electrons.

Reaction center

A complex of proteins and pigments where charge separation occurs, triggering the electron transport chain in photosynthesis.

Reduction

A chemical reaction where a molecule gains electrons, often associated with energy gain.

Regeneration of RuBP

The final stage of the Calvin cycle where RuBP is regenerated, allowing the cycle to continue.

Ribulose 1,5-bisphosphate (RuBP)

A five-carbon compound that combines with CO2 in the Calvin cycle to form 3-phosphoglycerate.

Rubisco

Ribulose bisphosphate carboxylase/oxygenase; the enzyme that catalyzes the first step of carbon fixation in the Calvin cycle.

Stomata

Small openings on the surface of leaves that allow gas exchange, including the intake of CO2 for photosynthesis.

Stroma

The fluid-filled space in chloroplasts surrounding the thylakoid membranes where the Calvin cycle takes place.

Thylakoid membrane

The internal membrane in chloroplasts that contains the components for the light-dependent reactions of photosynthesis.