(LE 2) Interactions Between Cells & the Extracellular Environment Flashcards
What is diffusion rate dependent on?
- magnitude of concentration gradient
- permeability of membrane (directly related)
- temperature (directly proportional)
- membrane surface area (microvilli; directly related)
- molecule size (inversely proportional)
What is carrier-mediated transport?
uses specific protein transporters
- facilitate diffusion (no energy)
- active transport (against gradient; req ATP)
What is molecular weight?
atomic weight of all atoms in compound
What is a mole?
6.02 x 10^23
1 mole = mw of a compound in grams
What is 1 molar solution?
1 mole of solute dissolved in 1L of solution
What is 1 molal solution?
1 mole of solute dissolved with 1L of solution
What is osmolality?
total molality of a solution
What is Osm related to the freezing point of a solution?
Freezing point dependent on solution concentration
- 1 molal solution depresses freezing point of water by -1.86° C
What is the Osm of blood?
0.3 Osm = 300 mOsm
How does the body regulate blood osmolality?
What is facilitated diffusion?
passive transport down concentration gradient by carrier proteins
- increase permeability
What do carrier-mediated transport proteins exhibit?
specificity: for single molecule
competition: among substrates for transport
saturation: when all carriers are occupied (Tm: transport maximum)
What is required for active transport?
ATP and carrier protein
What is the Na+/K+ pump?
Uses ATP to move 3 Na+ out and 2 K+ in against their gradients
What is secondary active transport?
movement of a molecule down its gradient coupled to the movement of another molecule against its gradient
