Biol 1211: Cellular Transport

Vocabulary practice flashcards covering cell membrane structure, passive transport, active transport, and bulk transport from Biology 1211.

Plasma Membrane

Also called the cell membrane; a bilayer of phospholipids that controls entry and exit of substances, maintains internal conditions, and controls communication with other cells and the environment.

Phospholipid Bilayer

A two-layer membrane structure where the hydrophobic tails point to the inside and the hydrophilic heads point to the outside, excluding dissolved cytoplasmic and extracellular substances to act as a barrier.

Fluid Mosaic Model

A model of cell membrane structure describing the membrane as a mosaic of protein molecules bobbing around within a fluid phospholipid bilayer.

Cholesterol

A modified lipid with a ring structure embedded in the hydrophobic region of the membrane that reduces fluidity at high temperatures and increases fluidity at low temperatures to maintain membrane stability.

Integral Protein

A membrane protein embedded within the lipid matrix that transports molecules and transfers signals across the membrane.

Peripheral Protein

A membrane protein that adheres to integral proteins or penetrates only a small portion of the lipid membrane.

Glycoprotein

A membrane protein with a carbohydrate attached, located on the outer surface of the cell membrane.

Glycolipid

A membrane lipid with a carbohydrate attached, exposed on the outer surface of the cell membrane.

Cell-Surface Marker

A glycolipid or glycoprotein located on the outside of the membrane that identifies the cell type.

Passive Transport

The movement of substances across a cell membrane that does not require cellular energy.

Simple Diffusion

The passive movement of solute particles from an area of high concentration to an area of low concentration until evenly dispersed; occurs across membranes for small, non-polar molecules.

Osmosis

The passive movement of free water molecules across a semipermeable membrane to equalize concentration.

Facilitated Diffusion

The passive transport of solutes across a membrane through membrane proteins down their concentration gradient without requiring energy.

Channel Protein

A membrane transport protein that provides a selective channel allowing a specific solute to pass through down its concentration gradient.

Carrier Protein

A membrane transport protein that binds a specific solute on one side of the membrane and physically transports it across to the other side.

Active Transport

The movement of molecules against their concentration gradient from low concentration to high concentration using specific transmembrane proteins and energy in the form of $\text{ATP}$.

$\text{Na}^+/\text{K}^+$ Pump

An active transport antiporter that consumes $\text{ATP}$ to pump sodium ions outside the cell and potassium ions inside the cell, establishing concentration gradients for cellular communication and secondary transport.

Coupled Transport

A transport process in which the movement of one substance down its concentration gradient facilitates the movement of another substance against its concentration gradient in the same direction without direct $\text{ATP}$ expenditure.

Uniporter

A transport protein involved in facilitated diffusion that moves one molecule in one direction across the membrane.

Antiporter

An active transport protein that moves two different molecules through the same protein in two different directions.

Symporter

A coupled transport protein that moves two different molecules through the same protein in the same direction.

Endocytosis

A form of bulk transport that brings substances into the cell through inward budding and vesicle formation of the plasma membrane.

Phagocytosis

A specific type of endocytosis involving the inward budding of the membrane to transport large objects, very large molecules, or entire cells into the cell.

Pinocytosis

A specific type of endocytosis involving the inward budding of the membrane to take in bulk water into the cell.

Exocytosis

A bulk transport process involving the movement and secretion of molecules out of the cell.