5.2 The Light-Dependent Reactions of Photosynthesis Flashcards

A set of vocabulary flashcards covering the light-dependent reactions of photosynthesis, including light properties, pigments, and the function of photosystems.

Visible light

The fraction of electromagnetic radiation (solar energy) emitted from the sun that humans can see.

Wavelength

The distance between two consecutive, similar points in a series of waves, such as from crest to crest or trough to trough.

Electromagnetic spectrum

The range of all possible wavelengths of radiation emitted from the sun.

Chlorophyll a

A pigment found in all photosynthetic organisms that absorbs wavelengths from the blue and red ends of the visible spectrum and reflects green.

Chlorophyll b

A pigment that absorbs blue and red-orange light for photosynthesis.

Carotenoids

A type of pigment in photosynthetic organisms identified by its specific absorption spectrum of visible light.

Absorption spectrum

The specific pattern of wavelengths a pigment absorbs from visible light.

Photosystem

A grouping of pigment molecules and proteins located in the membranes of thylakoids where the light-dependent reactions begin.

Photon

A quantity or "packet" of light energy absorbed by a pigment molecule.

Photosystem II

The photosystem that transfers a free electron to the electron transport chain and splits a molecule of water to replace the donated electron.

Electron transport chain

A series of proteins inside the thylakoid membrane that uses energy from electrons to pump hydrogen ions against their concentration gradient.

Photosystem I

The photosystem that accepts an electron from the transport chain and uses a photon to re-energize it for the formation of NADPH.

ATP synthase

An embedded protein complex that allows hydrogen ions to pass through the thylakoid membrane, attaching a third phosphate to ADP to form ATP.

Chemiosmosis

The flow of hydrogen ions from an area of high concentration to low concentration through a semi-permeable structure like ATP synthase.

Photophosphorylation

The process of forming ATP from ADP using the energy generated by the hydrogen ion stream in the light-dependent reactions.

NADPH

An energy-carrier molecule formed from $NADP^+$ and a hydrogen ion ($H^+$) during the light-dependent reactions.