Diffusion Flashcards
Function of cell membrane surrounding organelles
Separate organelles
Isolate enzymes
Act as surfaces for reactions e.g rough ER protein synthesis
Control entry and exit of substances into organelle ( Water potential )
Internal transport system
Cell membrane only allows what type of molecules
Small , non polar and lipid soluble molecules
So it is more difficult for
Large
Polar
Water soluble molecules
To pass through cell membrane
Passive transport
Energy comes from natural inbuilt motion of particles rather than external source of ATP
e.g Diffusion
Active transport
Requires metabolic therapy energy (ATP)
e.g Active transport as it is going against the concentration gradient (low to high)
Simple diffusion
The net movement of molecules or ions from a region where they are highly distributed to one where their concentration is lower until at equilibrium
Example of small non polar
Oxygen and carbon dioxide
Factors affecting diffusion
Temperature (More energy for particles the faster they move )
Surface area (More surface area more area for particles to diffuse through) Usually shown as folded organelle
Thickness of exchange surface ( Less distance for particles to travel )
Concentration gradient
Facilitated diffusion by the carrier protein
When the molecule is too large to pass through the cell membrane it binds to a site of the carrier protein and makes the carrier protein change shape to allow the large molecule diffuse through
Facilitated diffusion by channel protien
Molecules that have a charge and a water soluble can dissolve through the channel protein into the cell
Facilitated diffusion definition
Large , polar and water soluble molecules diffuse through the membrane by the specialised carrier protein or dissolving through channel proteins
Factors affecting facilitated diffusion
Number of proteins
Higher concentration gradient
