CIBI 3031 Terms to Know Instructor: Kristin Peterson

Chapter 6: Glossary of selected key terms (términos clave selectos)

activation energy / energía de activación

Minimum amount of energy required to get a specific reaction going, with or without the help of an enzyme. Reactions differ in the amount required.

active site / sitio activo

Crevice in an enzyme molecule where a specific reaction is catalyzed.

ADP / ADP

Nucleotide consisting of adenine, ribose, and two phosphate groups; can be phosphorylated to form ATP.

ATP / ATP

Nucleotide with adenine, ribose, and three phosphate groups; delivers energy to most energy-requiring metabolic reactions.

ATP/ADP cycle / ciclo del ATP/ADP

ADP forms from ATP, then ATP is regenerated from ADP, through the transfer of inorganic phosphate or a phosphate group.

binding energy / energía de enlace

Energy released when weak bonds that form between a substrate, enzyme, and any cofactor break during the transition state; the partial payment on energy cost of a reaction (the activation energy).

bioluminescence / bioluminiscencia

Fluorescent light produced by an organism through an ATP-driven reaction involving enzymes (luciferases).

chemical energy / energía química

Potential energy of molecules.

chemical equilibrium / equilibrio químico

Time when a reversible reaction runs both ways at about same rate.

coenzyme / coenzima

Enzyme helper; a nucleotide that transfers electrons and H atoms stripped from substrates to a different reaction site.

cofactor / cofactor

Metal ion, coenzyme, or other organic compound that assists an enzyme in catalysis or that transfers atoms, functional groups, or electrons to a different reaction site.

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.

energy carrier / portador de energía

Molecule that delivers energy from one reaction site to another; mainly ATP.

entropy / entropía

Measure of the degree of disorder in a system (how much energy has become disorganized, usually as dispersing heat, and is no longer available to do work). All systems need energy inputs to counter entropy.

enzyme / enzima

A type of protein or one of the few RNAs that catalyze reactions between substances, most often at functional groups.

feedback inhibition / inhibición por retroalimentación

Mechanism by which a cellular change resulting from some activity shuts down the activity that brought it about.

first law of thermodynamics / primera ley de la termodinámica

The total amount of energy in the universe is constant. Energy cannot be created from nothing and existing energy cannot be destroyed.

free radical / radicales libres

Any unbound molecular fragment with an unpaired electron.

heat / calor (energía térmica)

Thermal energy; a form of kinetic energy.

induced-fit model / modelo de adaptación inducida

When bound to an active site, a substrate promotes reactivity by altering an enzyme's shape; it brings about a more precise molecular fit betweeen the two.

intermediate / intermediario

Substance that forms between the start and end of a metabolic pathway.

kinetic energy / energía cinética

Energy of motion.

law of conservation of mass / ley de conservación de la masa

The total mass of all substances entering a reaction equals the total mass of all products.

metabolic pathway / vía metabólica

Orderly sequence of enzyme-mediated reactions by which cells maintain, increase, or decrease the concentrations of particular substances.

metabolism / metabolismo

All the controlled, enzyme-mediated chemical reactions by which cells acquire and use energy to synthesize, store, degrade, and eliminate substances in ways that contribute to growth, survival, and reproduction.

oxidation-reduction reaction / reacción de óxido-reducción

A transfer of an electron (and often an unbound proton, or H⁺) between atoms or molecules.

phosphorylation / fosforilación

An enzyme activates a molecule by attaching inorganic phosphate to it or by mediating a phosphate-group transfer to it, as from ATP.

potential energy / energía potencial

A stationary object's capacity to do work owing to its position in space or to the arrangement of its parts.

product / producto

Substances left at end of a reaction.

reactant / reactivo

Substance that enters a reaction.

second law of thermodynamics / segunda ley de la termodinámica

A law of nature stating that the spontaneous direction of energy flow is from organized forms to less organized forms; with each conversion, some energy is randomly dispersed in a form (usually heat) not as useful for doing work.

substrate / sustrato (reactivo)

Reactant or precursor for a specific enzyme-mediated metabolic reaction.

transition state / estado de transición

The point when a reaction can run either to product or back to reactant.

transport protein / proteína de transporte

Membrane protein that passively or actively assists specific molecules or ions across a membrane's lipid bilayer. The solutes pass through a channel in its interior.