9.2 Flashcards
Simple Diffusion
Diffusion that’s directly across the lipid bilayer of the cell membrane.
Small and nonpolar molecules can do simple diffusion.
No energy requirement. (aka, passive)
Facilitated Diffusion
Diffusion through protein channels.
Specific molecules for specific channels
Also passive
Omosis
Diffusion of water across a semi-permeable membrane to dilute higher solute concentrations
Hypertonic
Higher % solute
Lower % water
Hypotonic
Higher % water
Lower % solute
Isotonic
Equal % water and solute (equilibrium)
Active transport
When “protein” pumps push molecules against the concentration gradient
Costs ATP
Exocytosis
When vesicles take in a large molecule or a large amount of molecules
Endocytosis
When vesicles take out a large molecules or a large amount of molecules
Phospholipid
Has a hydrophobic tail and a hydrophilic head, being able to form long chains of them, bonding tail-to-tail, creating a lipid bilayer.
SA:V ratio
Molecules diffuse best over small volumes, and large surface areas. Thus, a small SA:V ratio is really important to cells for diffusion.
Compare and contrast the types of diffusion
Simple: Takes in small, nonpolar molecules. No energy required or transport proteins required.
Facilitated: Requires channel proteins. Takes in larger, possibly polar, molecules. No energy required.
Active transport: Requires protein pumps. Moves molecules against concentration gradient. Costs ATP.
