Biology - Cell Physiology (Simple diffusion, facilitated diffusion and active transport)

What is diffusion?

The net movement of a substance from where it is in higher concentration to where it is in lower concentration.

What can pass through the bilayer without a protein?

Lipid-soluble / non-polar / small molecules.

Can water pass through the bilayer?

Water can pass through but water-soluble substances cant because of the hydrophobic nature of the bilayer.

How does concentration gradient affect the rate of diffusion?

The greater the gradient, the faster the rate of diffusion.

How does size of the molecule affect the rate of diffusion?

The smaller the molecule, the faster the rate of diffusion.

How does temperature affect the rate of diffusion?

Higher temperature means molecules have more kinetic energy so the rate of diffusion is faster.

How does thick of exchange surface affect the rate of diffusion?

A thinner exchange surface means a shorter diffusion shorter diffusion so a faster rate of diffusion.

How does surface area affect the rate of diffusion?

The greater the surface area, the faster the rate of diffusion.

What is facilitated diffusion?

When the movement of substances is helped by a protein.

What do channel proteins do?

They have a hydrophilic core and allow polar ions to pass through the bilayer, some are gated.

What do carrier proteins do?

Carry specific ions and molecules, they have specific receptor sites that match specific molecules, they change shape and release the molecule on the other side.

What is the rate of facilitated diffusion dependant on?

The amount of proteins.

What is active transport?

Involves substances being moved against the concentration gradient.

What is required for active transport?

Energy.

What do cells that carry out active transport have?

They have many mitochondria so that ATP can be supplied

What type of proteins does active transport involve?

Carrier proteins.