14B Facilitated Diffusion across Membranes

A collection of vocabulary flashcards covering key terms and concepts from the lecture on facilitated diffusion across membranes.

Valinomycin

An ionophore that increases K+ permeability across membranes without energetic cost.

Selectivity Filter

A structure in the potassium ion channel that allows selective transport of K+ over Na+.

K+ channel

An ion channel that conducts potassium ions down their electrochemical gradient.

Ion Channels

Proteins that allow the passage of ions across cell membranes; often gated.

Gated Channels

Ion channels that can open or close in response to stimuli.

Aquaporins

Channel proteins that facilitate rapid movement of water across cell membranes.

Passive Transport

Movement of molecules across membranes without energy input; driven by concentration gradient.

Facilitated Diffusion

Transport of substances across a membrane via protein channels; highly selective.

Glut1 Permease

A glucose transporter in erythrocytes that facilitates glucose diffusion.

Tetramer

A protein structure made up of four subunits.

Action Potential

Transient changes in membrane potential that facilitate neuronal signaling.

Hydration Shell

The layer of water molecules surrounding ions in solution, replaced by peptide carbonyls in K+ channels.

Conformation Changes

Alterations in the structure of proteins necessary for opening and closing channels.

Saturation Behavior

A phenomenon where the rate of transport reaches a maximum despite increases in concentration.

D-glucose

A simple sugar that is a primary energy source transported by Glut permeases.

Electrochemical Gradient

The combined effect of concentration and electric gradients affecting ion movement.

Facilitated Transport

A transport mechanism that greatly increases permeability and can be saturated.

Cytoplasmic Signaling

Communication between cells often mediated via ion channels and receptors.

Glut Transporters

A family of glucose transport proteins with varying affinities and tissue distribution.

Membrane-spanning Helices

Structural elements of membrane proteins that allow anchoring in the lipid bilayer.

Erythrocytes

Red blood cells that transport oxygen and contain Glut1 for glucose uptake.

Nerve Impulses

Electrical signals that travel along neurons mediated by ion channels.

Coordination

The arrangement of atoms, often in a molecular structure, enhancing ion transport.

Osmotic Pressure

The pressure required to prevent the flow of water across a semipermeable membrane.

Fixed Concentration of Transporter

Refers to a constant number of transport proteins available for diffusion.

Extracellular Glucose Concentration

The amount of glucose available outside the cell, influencing diffusion rates.