Module 9: Patterns of Electron Flow Through Light Reaction Events

Flashcards covering key vocabulary, stages, molecules, and historical contributions related to light reaction events and electron flow in photosynthesis.

Photosynthesis

A biological process that captures energy from outer space and converts it into chemical compounds.

Light-dependent Reactions

The first stage of photosynthesis that uses light as a reactant, takes place within the thylakoid membrane, and converts solar energy into chemical energy in the form of NADPH and ATP.

Light-independent Reactions (Calvin-Cycle)

The second stage of photosynthesis that does not use light as a reactant, takes place in the stroma, and uses ATP, NADPH, and $CO_2$ to produce sugar.

Thylakoid

A sheet-like membrane-bound structure in chloroplasts wherein light-dependent photosynthesis reactions occur.

Photosystem I ($P700$) and Photosystem II ($P680$)

Pairs of photosystems contained within thylakoids in most photosynthetic organisms that work in tandem to produce energy that will later be used in the stroma.

Robert Hill and Fay Bendall (1960)

Researchers who proposed photoelectronic transfer in 1960, in which two light reactions (light I and II reaction) move electrons from water to carbon dioxide.

Chlorophyll

The pigment responsible for capturing light energy for photosynthesis; it absorbs mainly red and blue light while reflecting and transmitting green light.

ATP

Usable chemical energy acting as the energy currency of the cell, produced in light reactions to power the Calvin Cycle.

NADPH

A high-energy electron carrier produced during light reactions that powers the Calvin Cycle.

Non-Cyclic Electron Flow

The main, linear route of electron movement in light reactions where electrons move in one direction from water to $NADP^+$.

Cyclic Electron Flow

One of the two main pathways of electron movement in the light reactions of photosynthesis.

P680

A specific pair of chlorophyll a molecules located in the reaction center of Photosystem II that absorbs light energy passed from the light-harvesting complex.