Photosynthesis and the Calvin Cycle

Vocabulary terms and definitions related to the structures and biochemical processes of photosynthesis as described in the lecture notes.

Glyceraldehyde 3-phosphate (G3P)

An important precursor to the carbohydrate glucose ($C_6H_{12}O_6$) generated through anabolic redox reactions; two molecules of this substance are required to create one molecule of glucose.

Mesophyll

A type of leaf tissue found between layers of epidermis and a waxy cuticle where chloroplasts are abundant.

Stomata

Openings in each leaf that allow for the diffusion of $CO_2$ and $O_2$ to and from chloroplasts through the protective epidermis and cuticle.

Thylakoids

Membrane-bound sacs inside each chloroplast where light-dependent reactions take place; their internal space is referred to as the thylakoid space or lumen.

Stroma

A fluid-filled space surrounding the thylakoids where light-independent reactions, such as the Calvin cycle, take place.

Photosystem II (PS II)

The initial phase of photosynthesis in which water molecules are broken down into hydrogen ions ($H^+$), electrons ($e^-$), and oxygen.

ATP-synthase

An enzyme that allows chemiosmosis to take place; as $H^+$ flow through its internal structure back into the stroma, ADP is joined with phosphate to form ATP.

NADP-reductase

An enzyme that attaches electrons from Photosystem I and $H^+$ from the stroma to the coenzyme $NADP^+$ to reduce it into $NADPH$.

RubisCO

The enzyme that combines three molecules of $CO_2$ with three molecules of five-carbon RuBP during the Carbon Fixation phase of the Calvin cycle.

RuBP

A five-carbon molecule that combines with atmospheric $CO_2$ to start the Calvin cycle and is regenerated using ATP from the remaining five molecules of G3P.