CIBI 3031 Terms to Know Instructor: Kristin Peterson

Chapter 5: Glossary of selected key terms (términos clave selectos)

ABC transporter / transportador ABC

One of a class of ATP-driven membrane pumps, each for a specific substrate (e.g., ions, sugars, amino acids).

active transport / transporte activo

Pumping of a specific solute across a cell membrane against its concentration gradient, through a transport protein's interior. Requires an energy boost, typically from ATP.

adhesion protein / proteína de adherencia

Plasma membrane protein that helps cells locate tissue mates and stick together.

biofilm / biocapa

Huge microbial populations anchored to surfaces (e.g., lung epithelia) by their own sticky, stiff polysaccharide secretions.

bulk flow/ flujo a granel

In response to a pressure gradient, movement of more than one kind of molecule in the same direction in the same medium.

calcium pump / bomba de calcio

Active transporter protein specific for calcium ions.

communication protein / proteína de comunicación

Part of a protein complex that forms an open channel between cytoplasm of adjoining cells.

concentration gradient / gradiente de concentración

A difference in the number per unit volume of molecules or ions of a substance between two regions. Molecules collide constantly and careen outward to a region where they are less concentrated. All substances tend to diffuse down such gradients.

diffusion / difusión

Net movement of like molecules or ions down their concentration gradient.

electric gradient / gradiente eléctrico

Difference in electric charge between adjoining regions.

endocytosis / endocitosis

Cell uptake of substances via vesicle formation. Receptor-mediated endocytosis, phagocytosis, and the bulk transport of extracellular fluid are three modes of endocytosis.

exocytosis / exocitosis

Release of a vesicle's contents at cell surface as it fuses with and becomes part of the plasma membrane.

fluid mosaic model / modelo del mosaico fluido

A cell membrane is a mix of lipids (organized as a bilayer) and proteins. Structural lipids make it largely impermeable to water-soluble molecules yet impart fluidity by packing variations and motions. Diverse proteins perform most membrane functions (e.g., transport, signal reception).

hydrostatic pressure / presión hidrostática

Pressure exerted by a volume of fluid against a wall, membrane, or some other structure that encloses the fluid.

hypertonic solution / solución hipertónica

A fluid having a greater solute concentration relative to another fluid.

hypotonic solution / solución hipotónica

A fluid that has a lower solute concentration relative to another fluid.

isotonic solution / solución isotónica

A fluid having the same solute concentration as a fluid against which it is being compared.

lipid bilayer / bicapa lipídica

Phospholipids, mostly, arranged in two layers; the structural basis of all cell membranes. Hydrophobic tails are sandwiched between the hydrophilic heads; the heads are dissolved in intracellular or extracellular fluid.

osmosis / ósmosis

In response to a water concentration gradient, the diffusion of water between two regions that a selectively permeable membrane separates.

osmotic pressure / presión osmótica

Pressure that operates after hydrostatic pressure develops in an enclosed region (e.g., a cell); it counters water's inward diffusion (stops further rises in fluid volume).

passive transport / transporte pasivo

Event in which a transport protein that spans a cell membrane passively permits a solute to diffuse through its interior. Also called facilitated diffusion.

phagocytosis / fagocitosis

Of some cells, engulfment of an extracellular target by way of pseudopod formation and endocytosis.

phospholipids / fosfolípido

Organic compound that has a glycerol backbone, two fatty acid tails, and a hydrophilic head of two polar groups (one being phosphate). Phospholipids are the main structural component of cell membranes.

pressure gradient / gradiente de presión

A difference in pressure between two adjoining regions.

receptor protein / proteína de receptora

Membrane protein (or cytoplasmic protein) that triggers a change in cell activities after it binds signaling molecule.

recognition protein / proteína de reconocimiento

One of a class of plasma membrane proteins that distinguish nonself (foreign) from self (belonging to a body tissue).

selective permeability / permeabilidad selectiva

Of a cell membrane, a capacity to let some substances but not others cross at certain sites, at certain times owing to its bilayer structure and its transport proteins.

sodium-potassium pump / bomba de sodio-potasio

Type of membrane transport protein that, when activated by ATP, selectively transports potassium ions across a membrane against its concentration gradient, and passively allows sodium ions to cross in the opposite direction.

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.