Facilitated Diffusion Flashcards
Why don’t all substances diffuse across the membrane at the same rate?
The centre of the cell membrane is hydrophobic.
What substances can diffuse rapidly across the membrane?
Hydrophobic substances.
What substances can’t diffuse across the membrane?
Ions and polar molecules.
What polar molecule can diffuse across the membrane and why?
Water molecules, as they are very small.
Why do cells use facilitated diffusion?
Many substances that cells require are hydrophilic and can’t diffuse across membranes.
What do hydrophilic substances diffuse across via?
Protein molecules.
What are the two proteins involved in facilitated diffusion?
Carrier proteins and protein channels.
Why are intrinsic proteins used?
They completely span the membrane from one side to the other so they can fully transport molecules.
What do carrier proteins have?
A binding site for a specific chemical.
What happens when the chemical bonds to the carrier protein?
It causes the carrier protein to change shape.
What does the carrier proteins change in shape cause?
The chemical to be release across the membrane.
What does a protein channel have?
A central pore.
What does a protein channels pore contain?
Water.
What are protein channel pores lined with?
Hydrophilic amino acids.
What protein is selective?
Protein channels.
