Physiology Sept. 19th (rest of it)

These flashcards cover key terms and concepts related to photosynthesis and the Calvin-Benson Cycle.

Light Harvesting Complex (LHC)

A structure in photosystems that captures photons and transfers energy to the reaction center.

Photosystem I (PSI)

A photosynthetic unit that absorbs light and transfers electrons to reduce NADP+ to NADPH.

Photosystem II (PSII)

A photosystem that captures light energy to oxidize water and generate electrons.

NADPH

A reducing agent produced during the light reactions of photosynthesis; used in the Calvin-Benson cycle.

Calvin-Benson Cycle

The light-independent reactions of photosynthesis that fix carbon dioxide into organic molecules.

Rubisco

An enzyme that catalyzes the first step of the Calvin-Benson cycle, fixing CO2 to ribulose bisphosphate.

Plastoquinone (PQ)

A molecule that transports electrons within the photosynthetic electron transport chain.

Carbon Fixation

The process of converting inorganic carbon (CO2) into organic compounds in the Calvin-Benson cycle.

Glycerate-3-phosphate (GP)

A three-carbon compound produced during the Calvin-Benson cycle; key intermediate in carbohydrate synthesis.

Triose phosphate (TP)

A three-carbon sugar formed as an end product of the Calvin-Benson cycle, used to form glucose.

Proton gradient

A difference in proton concentration across a membrane, used to generate ATP during photosynthesis.

Photosynthetic electron transport chain

A series of protein complexes that transfer electrons from water to NADP+, creating a proton gradient for ATP production.

Oxygen-evolving complex

A component of PSII that oxidizes water, releasing oxygen and providing electrons for the electron transport chain.

Light-driven reactions

The phase of photosynthesis that occurs in the thylakoid membranes, capturing light energy to produce ATP and NADPH.

Non-photochemical quenching

A protective mechanism to dissipate excess light energy as heat in plants.

Xanthophyll Cycle (in Low light)

Violaxanthan predominates

Xanthophyll Cycle (in High light)

Violaxathin is enzymatically de-epoxidized to become antheraxanthin and then zeaxathin, which is highly effective at absorbing excess energy and dissipating it as heat

Second Line of Defence?

Scavenging systems (e.g superoxide dismutase and catalase)

Carboxylation

3CO2 + 3RuBP —> 6GP

Reduction of GP

6GP + 6ATP + 6NADPH —> 6TP and all the other shi

Regeneration of RuBP

(One of the TP is exported from the cycle as net sugar output) Remaining 5 r rearranged thru a series of enzymatic rxns to regenerate 3RuBP