Photosynthesis Lecture Notes

Comprehensive vocabulary flashcards covering the structured components and metabolic pathways of C3 photosynthesis, including the light-dependent reactions and the Calvin cycle phases.

C3 photosynthesis

The most common version of photosynthesis which involves anabolic redox reactions to generate glyceraldehyde 3-phosphate (G3P).

Glyceraldehyde 3-phosphate (G3P)

An important precursor to the carbohydrate glucose ($C_6H_{12}O_6$) and other biomolecules; for every two G3P made, one molecule of glucose can be created.

Chloroplasts

Specialized membrane-bound organelles located in the cells of green plant tissues where photosynthesis occurs.

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.

Thylakoids

Membrane-bound sacs inside chloroplasts where the light-dependent reactions take place.

Granum

A stack of thylakoids; multiple stacks are referred to as grana.

Stroma

The fluid-filled space surrounding the thylakoids where light-independent reactions take place.

Photosystem II (PS II)

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

Electron Transport Chain (ETC)

A series of stages in the thylakoid membrane where $e^-$ travel, causing $H^+$ from the stroma to be concentrated in the lumen.

ATP-synthase

The enzyme through which chemiosmosis occurs, allowing $H^+$ to flow back into the stroma to join ADP with phosphate to form ATP.

Photosystem I (PS I)

The second phase of photosynthesis where electrons are re-energized by sunlight before moving to the enzyme NADP-reductase.

NADP-reductase

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

Calvin cycle

A series of light-independent reactions in the stroma that intake atmospheric $CO_2$ and combine it with RuBP to eventually yield G3P.

Carbon Fixation

The first phase of the Calvin cycle where three molecules of $CO_2$ are combined with three molecules of five-carbon RuBP by the enzyme RubisCO.

3PG (3-PGA)

A three-carbon molecule formed when the unstable six-carbon intermediate produced during carbon fixation immediately breaks down.

Reduction Phase

The second phase of the Calvin cycle where six molecules of ATP and NADPH are used to convert 3PG into BPG, and then into G3P.

Regeneration Phase

The third phase of the Calvin cycle where five molecules of G3P are converted back into RuBP using three molecules of ATP.

Photosynthesis Chemical Equation

The general summary equation for the process: $6CO_2 + 6H_2O + \text{Sunlight} \rightarrow C_6H_{12}O_6 + 6O_2$.