AP Bio Chapter 10

Chloroplast

A double-membrane-bound organelle found in plant cells and eukaryotic algae that conducts photosynthesis by capturing sunlight with chlorophyll

Autotroph

An organism that produces its own organic food molecules (such as glucose) from inorganic raw materials using energy from sunlight or chemical reactions

Photosynthesis

The metabolic process where photoautotrophs (such as plants, algae, and cyanobacteria) capture light energy and convert it into stored chemical energy in the form of carbohydrates, using carbon dioxide and water while releasing oxygen as a byproduct

Stomata

Microscopic pores or openings in the epidermis of plant leaves and stems that allow for gas exchange (CO₂ and O₂) and transpiration (water vapor loss)

Stroma

The dense, fluid-filled space surrounding the thylakoid membranes inside a chloroplast

Thylakoid

A membrane-bound, flattened sac-like compartment located inside the chloroplast of plant cells and cyanobacteria

Chlorophyll

The primary green pigment in plants, algae, and cyanobacteria that absorbs light energy (primarily blue and red wavelengths) and reflects green light, driving the light reactions of photosynthesis

Photolysis

The light-driven splitting of a water molecule (H2O) during the light-dependent reactions of photosynthesis

Light reactions (light-dependent reactions)

The initial stage of photosynthesis that converts solar energy into chemical energy in the form of ATP and NADPH, releasing O2 as a byproduct

Calvin cycle (Calvin-Benson cycle/dark reactions/light-independent reactions)

Light-independent reactions, or dark reactions) is the set of chemical reactions that take place in the stroma of chloroplasts during photosynthesis. It uses the ATP and NADPH produced by the light-dependent reactions to fix carbon dioxide (CO2) into organic sugar molecules (G3P / glyceraldehyde-3-phosphate)

Photophosphorylation

The process of generating ATP from ADP and an inorganic phosphate group using light energy during the light-dependent reactions of photosynthesis

NADP+

A coenzyme that acts as an electron carrier in photosynthesis

NADPH

A high-energy electron carrier and reducing agent used in cellular metabolism, most notably during photosynthesis

Carbon fixation

The initial step of the Calvin cycle (light-independent reactions of photosynthesis) where inorganic carbon dioxide (CO2) from the atmosphere is incorporated into an organic molecule

Carotenoids

Yellow, orange, and red accessory pigments (tetraterpenoids) found in the chloroplasts of plants, algae, and photosynthetic bacteria

Light-harvesting complex

A protein complex bound with pigment molecules—such as chlorophyll a, chlorophyll b, and carotenoids—that captures light energy (photons) and funnels that excitation energy to the reaction center of a photosystem

Primary electron acceptor

The first molecule in a photosystem (located in the thylakoid membrane of chloroplasts) that receives a high-energy, photo-excited electron from the reaction center chlorophyll a molecule

Photosystem I

a light-capturing protein complex in the thylakoid membrane of chloroplasts that re-energizes low-energy electrons from the electron transport chain to reduce NADP⁺ into NADPH

Photosystem II

The first protein complex in the light-dependent reactions of photosynthesis found in the thylakoid membrane of chloroplasts

G3P

A three-carbon sugar molecule that acts as a vital intermediate and building block in both cellular respiration and photosynthesis

Rubisco

The crucial enzyme that catalyzes the first major step of carbon fixation in the Calvin cycle during photosynthesis

Regeneration of RUBP

The final phase of the Calvin cycle where remaining G3P (glyceraldehyde-3-phosphate) molecules are rearranged using ATP energy to recreate the 5-carbon acceptor molecule, ribulose-1,5-bisphosphate (RuBP)