CIBI 3031 Terms to Know Instructor: Kristin Peterson

Chapter 7: Glossary of selected key terms (términos clave selectos)

absorption spectrum / espectro de absorción

Range of wavelengths that one or more specified pigments can absorb.

anthocyanin / antocianina

Blue or red accessory pigment.

autotroph / autótrofo

Any organism that makes its own food with an environmental energy source (e.g., sunlight) and CO₂ as its carbon source.

C3 plant / planta C3

Plant that uses three-carbon PGA as the first intermediate for carbon fixation.

C4 plant / planta C4

Plant that uses oxaloacetate (a four-carbon compound) as the first intermediate for carbon fixation. CO₂ is fixed twice, in two cell types; helps counter photorespiration.

Calvin-Benson cycle / ciclo de Calvin-Benson

Light-independent cyclic reactions of photosynthesis that form sugars, using ATP energy, NADPH, and CO₂.

CAM plant / planta CAM

Type of plant that conserves water by opening stomata only at night, when it fixes carbon dioxide by means of a C₄ pathway.

carbon fixation / fijación de carbono

First of the light-independent reactions. Rubisco, an enzyme, affixes carbon (from CO₂) to RuBP or to another compound for entry into the Calvin-Benson cycle.

carotenoid / carotenoide

An accessory pigment of photosynthesis; e.g., fucoxanthin.

chemoautotroph / quimioautótrofo

Any prokaryotic cell that synthesizes its own food using carbon dioxide as the carbon source and an inorganic substance as the energy source.

chlorophyll / clorofila

Main photosynthetic pigment. Chlorophylls absorb all wavelengths of visible light but not much of green and yellow ones.

chloroplast / cloroplasto

The organelle of photosynthesis in plants and many protistans.

electromagnetic spectrum / espectro electromagnético

All wavelengths from radiant energy less than 10-5 nm long to radio waves more than 10 km long.

electron transfer chain / cadena de transferencia de electrones

Organized array of membrane-bound enzymes and cofactors that accept and donate electrons in series. It sets up an electrochemical gradient that makes H⁺ flow across the membrane. The flow energy drives ATP formation at ATP synthases.

fluorescence / fluorescencia

A destabilized molecule emits light when reverting to more stable form.

heterotroph / heterótrofo

Organism unable to make its own organic compounds; feeds on autotrophs, other heterotrophs, organic wastes.

hydrothermal vent ecosystem / ventiladero hidrotérmico

A steaming fissure in the deep ocean floor; has unique ecosystems.

light-dependent reactions / reacciones dependientes de la luz

The first stage of photosynthesis. Sunlight energy is trapped and converted to chemical energy of ATP, NADPH, or both, depending on the pathway.

light-independent reactions / reacciones independientes de la luz

Second stage of photosynthesis; sugar-building reactions that require phosphate-group transfers from ATP, electrons and H atoms from NADPH, and carbon from CO₂. The phosphorylated sugars from these reactions are then converted to end products (e.g., sucrose, cellulose, starch).

PGA / PGA

Important intermediate of glycolysis and of the Calvin-Benson cycle.

PGAL / PGAL

Intermediate of glycolysis and of the Calvin-Benson cycle.

photoautotroph / fotoautótrofo

Photosynthetic autotroph; any organism that synthesizes its own organic compounds using CO₂ for carbon atoms and sunlight for energy. Nearly all plants, some protistans, and a few bacteria do this.

photolysis / fotólisis

Reactions split water molecules using photon energy. The released electrons, hydrogen used in noncyclic pathway of photosynthesis; oxygen is a by-product.

photon / fotón

One unit of energy of visible light.

photosynthesis / fotosíntesis

Sunlight energy trapped, converted to chemical energy (ATP, NADPH, or both); then synthesis of sugar phosphates that are converted to sucrose, cellulose, starch, and other end products. The main pathway by which energy and carbon enter the web of life.

photosystem / fotosistema

Cluster of many light-trapping pigments in a photosynthetic membrane.

phycobilin / ficobilina

Type of accessory pigment; notably abundant in red algae and in cyanobacteria.

pigment / pigmento

Any light-absorbing molecule.

reaction center / centro de reacción

The only molecule (a special chlorophyll a) that can pass electrons out of a photosystem to a nearby acceptor molecule.

rubisco / rubisco

An enzyme that catalyzes attachment of the carbon atom from CO₂ to RuBP and so starts the Calvin-Benson cycle of the light-independent reactions.

RuBP / RuBP

An enzyme that catalyzes attachment of the carbon atom from CO₂ to RuBP and so starts the Calvin-Benson cycle of the light-independent reactions.

stoma (stomata) / estoma

A gap between two guard cells in leaf or stem epidermis. Opens or closes to control CO₂ movement into a plant and H₂O and O₂ out of it. Stomata help plants conserve water.

stroma / estroma

A semifluid matrix between the thylakoid membrane system and two outer membranes of a chloroplast; a zone where sucrose, starch, cellulose, and other end products of photosynthesis are assembled.

thylakoid / membrana tilacoidal

Inner chloroplast membrane often folded as interconnected flattened sacs; forms a single compartment for hydrogen ions. Light-trapping pigments, and enzymes used to form ATP, NADPH, or both, are embedded in it.

wavelength / longitud de onda

A wavelike form of energy in motion. The horizontal distance between the crests of every two successive waves.