Diffusion and Facilitated diffiusion Flashcards
What is diffusion
movement of molecules of a liquid or gas from an area where they are highly concentrated to an area where they are at a lower concentration
What does facilitated diffusion involve
Proteins in the membrane that allow only specific substances to move through passively down their concentration gradient
What are gated channels
There are channel proteins in the axon membrane that allow
calcium, sodium, potassium ions to pass through.
Describe the conditions needed for the passive transport of molecules into a cell
A highly concentrated area
to a lowly concentrated area
right temperature
What is the difference between simple and facilitated diffusion
Simple diffusion can only move material in the direction of a concentration gradient
facilitated diffusion moves materials with and against a concentration gradient.
Why does a carrier protein change shape when binded to a molecule
Allows the molecule to be released to the other side of the membrane
How does soluabuilty affect how a molecule is transported
lipid-soluble materials pass through plasma membranes more easily than polar materials, allowing a faster rate of diffusion
How does size affect how a molecule is transported?
The bigger the molecule the more difficult it to get through the protein channels i.e glucose so it needs to go through FD
Why cant ions pass through the lipid bilyar
Large polar or ionic molecules, which are hydrophilic, cannot easily cross the phospholipid bilayer.
Ions cannot diffuse through a lipid bilayer
Ions need a carrier protein to moive across the membrane either by AT of FD
the charges are repelled by the hydrophobic tails in the interior of the phospholipid bilayer.
Why does the rate of uptake change in FD
The rate increases when the concentration increases
This increases the concentration gradient
The curve starts to level of due to the channel proteins being saturated with molecules of the substance
