Photosynthesis: Light Reactions and the Calvin Cycle

This set of vocabulary flashcards covers the mechanisms of the light reactions and the Calvin cycle as described in the lecture notes.

Photons

Little packets of light energy coming from the sun that strike the pigment molecules in a photosystem.

Thylakoid membrane

A phospholipid bilayer where photosystems and the electron transport chain (ETC) are embedded.

Photosystem II

The cluster of molecules where light strikes and water molecules are split to replenish electrons.

Reaction center

The core of a photosystem where specific chlorophyll molecules reside and release electrons when they receive sufficient energy.

Electron transport chain (ETC)

A series or chain of molecules that move electrons and generate energy for the production of ATP.

NADP+

A molecule that picks up electrons and hydrogen ions to become NADPH, an electron carrier.

Thylakoid space

The area inside the center of the thylakoid where water splitting occurs and high concentrations of hydrogen ions are built up.

Stroma

The area outside the thylakoid membrane.

Fluorescence

The light energy given off when excited electrons return to their unexcited state because they have nowhere to go.

$$p680$$

The specific chlorophyll molecules in the reaction center of Photosystem II that most strongly absorb light at a wavelength of $680\,nm$.

$$p700$$

The special chlorophyll molecules found in Photosystem I that most strongly absorb light at a wavelength of $700\,nm$.

ATP synthase

An enzyme that uses the energy of hydrogen ions flowing down their concentration gradient to produce ATP from ADP and a phosphate.

Reduction

In chemistry and photosynthesis, the process of adding electrons to a molecule, such as adding electrons to $NADP+$ to form $NADPH$.

$CO_2$ fixation

The process in the Calvin Cycle where inorganic carbon dioxide is changed into an organic carbon-containing molecule like glucose.

Sucrose

A disaccharide that serves as the primary form of sugar for export and movement within a plant.

Starch

The primary form used by plants for the long-term storage of glucose.

Photosynthesis equation

The chemical formula summarizing the process: $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$.