Ch. 3 - B Flashcards
What is free permeability?
Membrane allows anything to pass through
What is selective permeability? (Semi-permeable)
Allows some stuff but not everything
What is impermeability?
Membrane doesn’t let anything come in
Do polar molecules pass through membrane easily?
No. Bc of phospholipid bilayer, heads are hydrophobic
Do non-polar molecules pass through membranes easily?
Yes. Bc phospholipid bilayer’s heads are hydrophobic = lipophilic
Name 5 types of membrane transport
Simple diffusion Facilitated diffusion Exocytosis, endocytosis, & phagocytosis Secondary active transport Primary active transport
What causes diffusion?
All molecules are in constant thermal motion
What is diffusion?
Molecules colliding, causing them to move away from each other
What small molecules diffuse quickly?
O2, CO2, H2O, & ions
How big are cells typically?
Around 10 um in diameter
What keeps our cells small?
Bc they depend on diffusion for most processes
Speed of diffusion depends on…
Size of cell
What is net diffusion?
Mass movement of material from greater concentration to lower
When does net diffusion stop?
Follows concentration gradient until cell reaches equilibrium
Equation for rate of net diffusion (Fick’s Law): what does “D” represent?
Diffusion coefficient (depends on size of molecule)
