Diffusion Flashcards
What are the 4 types of transport?
Simple Diffusion
Facilitated Diffusion
Osmosis
Active Transport
What is simple diffusion?
The net movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached.
Does simple diffusion require ATP?
No
What energy do the molecules have that they need to be able to move?
Kinetic energy.
In what (liquid, gases, solids) does simple diffusion occur in?
Liquids and gases.
Why does simple diffusion only occur in liquids and gases?
Because they have kinetic energy to enable them to flow.
What do molecules need to be to diffuse across a membrane in simple diffusion?
Lipid-soluble
Small
How is facilitated diffusion similar to simple diffusion?
They are both a passive process (not needing ATP).
How is facilitated diffusion different to simple diffusion?
Facilitated diffusion used proteins to transport molecules.
What can’t diffuse by simple diffusion?
Polar molecules
Ions
What does facilitated diffusion do?
Transports ions and polar molecules across membranes by using channel proteins and carried proteins.
How do channel proteins transport molecules across membranes?
They form tubes filled with water and this enables water-soluble ions to pass through the channel.
Are channel proteins selective? Why?
Yes because they only open in the presence of certain ions when they bind to the protein.
How do carrier proteins transport molecules across membranes?
They bind with a molecule such as glucose which causes a change in the shape of the protein. This shape change enables the molecule to be released to the other side of the protein.
Describe how movement across membranes occur by simple diffusion.
Lipid soluble or very small substances move from an area of high conc to an area of low conc down a concentration gradient across a phospholipid bilayer. It is a passive process meaning it doesn’t require energy from ATP or respiration only kinetic energy.
Describe movement across membranes by facilitated diffusion.
Water soluble (polar) and larger substances move down a conc gradient through specific channel and carrier proteins. It is a passive process meaning it doesn’t require energy from ATP or respiration only kinetic energy.
Explain the role of carrier and channel proteins in facilitated diffusion.
Shape/charge of protein determines which substances move. Channel proteins facilitate diffusion of water-soluble substances. Hydrophobic pore fills with water. Can open and close.
Carrier proteins facilitate diffusion of larger substances. Complementary substance attaches to binding site so protein changes shape to transport substance.
