Cell Membranes and Transport

Flashcards reviewing key vocabulary from a lecture on cell membranes and transport mechanisms.

Phospholipid

A molecule with both a polar (charged) region and a non-polar (uncharged) region.

Phospholipid Bilayer

The cell membrane, composed of two layers of phospholipids.

Extracellular Fluid

Fluid outside the cell.

Intracellular Fluid

Fluid inside the cell, also known as cytosol.

Water

A molecule (H2O) with a positive region and a negative region due to unequal sharing of electrons.

Covalent Bonds

The sharing of electrons between atoms.

Selective Permeability

The ability of a cell membrane to allow some molecules to pass through while preventing others from crossing.

Channel

A protein that spans the cell membrane, allowing polar molecules and ions to cross.

Cation

A positively charged atom.

Anion

A negatively charged atom.

Facilitated Diffusion

Diffusion requiring a protein channel or transporter to aid movement across the membrane.

Simple Diffusion

Diffusion directly across the phospholipid bilayer without the need for a channel.

Leakage Channels

Channels that are always open, allowing continuous diffusion.

Gated Channel

A channel that opens or closes in response to a specific signal.

Ligand

A signaling molecule that binds to a receptor, such as a neurotransmitter or hormone.

Ligand-Gated Channel

A channel that opens when a ligand binds to it.

Voltage-Gated Channel

A channel that opens in response to a change in voltage across the cell membrane.

Mechanically Gated Channel

A channel that opens in response to physical pressure or manipulation of the cell.