Diffusion & Active Transport Flashcards
How does the surface area of the membrane affect the rate of diffusion?
More membrane means more diffusion
How does the concentration of solutions affect the rate of diffusion?
Membrane thickness
How does the polar of a substance affect the rate of diffusion?
Non polar (charged) ions need protein channels to get through
Define Diffusion
The passive movement down a concentration gradient through the phospholipid bilayer
Define Facilitated Diffusion
Passive movement down a concentration gradient using transport proteins- either a channel or carrier protein
What is the question for Rate of Diffusion?
Rate of Diffusion=
(Surface Area x Difference in Concentration)/Length of Diffusion Path
What two substances MUST cross protein channels and how can this affect the rate of diffusion?
Amino Acids and Ions
-too many can decrease the rate
How does organic solvents (containing carbon) such as ethanol affect diffusion?
The plasma membrane becomes more fluid so the bilayer becomes unstable and more porus
How does decreased fluidity affect diffusion?
Makes the membrane unstable and does not let molecules pass through
Define a Plasmolysed Cell
The retraction of the cytoplasm and cell membrane from the cell wall as the cell loses water by osmosis. This happens if the external concentration is too high
Does lipid soluble go through by facilitated diffusion or regular?
Regular
What is required for active transport to take place?
ATP produced from respiration
Define Active Transport
Moving ions and molecules against the concentration gradient
How is it done?
Using intrinsic carriers
-thus can be limiting due to lack of space to go through
Hey substance stops Active Transport taking place?
Cyanide
- it inhibits an enzyme in mitochondria that is used in respiration
