Active and Passive Transport AP Biology

Active and passive transport for AP bio

Passive transport

Transport of a molecule that does not require energy from the cell because a solute is moving with/down its concentration or electrochemical gradient (high to low conc)

Concentration gradient

The difference in concentration of a substance between two areas, driving the movement of particles.

Dynamic equilibrium

A state where particles are evenly mixed and spread throughout with continuous back and forth movement at equal rates.

Diffusion

Movement of uncharged or nonpolar solute particles in a fluid or gas directly across the phospholipid bilayer.

Osmosis

Movement of water across the membrane using an aquaporin (protein).

Facilitated diffusion

Movement of polar or charged molecules across the membrane using an integral protein.

Spontaneous process

A process that occurs without external intervention, such as diffusion resulting from the constant motion of molecules.

High to low concentration

The direction substances move during diffusion, from areas of higher concentration to areas of lower concentration.

Selectively permeable membrane

A membrane that allows certain molecules to pass while blocking others.

Aquaporin

A specific channel protein for water that facilitates its movement across membranes.

Channel proteins

Proteins that provide a channel for molecules and ions to pass, often hydrophilic.

Gated channels

Channel proteins that only allow passage when there is a stimulus, not the solute being transported.

Carrier proteins

Proteins that undergo conformational changes to allow substances to pass through the membrane.

Energy requirement in facilitated diffusion

No energy is required for facilitated diffusion because substances are moving DOWN their concentration gradient.

Rate of diffusion

The speed at which different molecules diffuse across a membrane, which can vary based on the type of molecule.

Small ions, water, carbohydrates

Types of molecules that facilitated diffusion increases the rate of diffusion for.

Concentration gradient in osmosis

The movement of water from areas of low solute concentration to areas of high solute concentration.

Facilitated diffusion specificity

Each transport protein is specific for the substances it can facilitate movement for.