Ch 4 Diffusion Osmosis Flashcards
(43 cards)
Movement of molecules
from high to low concentration
Diffusion Equilibrium will start…
Randomly due to random thermal motion
When diffusion equilibrium is reached…?
molecule movement diminishes
What is flux
amount of substance that crosses the membrane
determined by the concentration difference
Bi directional movement
Net Flux
diifference between 2 one-way fluxes
diffusion equillibrium will have a net flux of…
zero
diffusion flux is directly proportional to…
concentration gradient
diffusuion times increase in proportion to what
the swaure of the distance
what is diffusion limited by
distance, the longer the distance the slower
lipophillic nonpolar substance diffuse easily or not?
diffuse easily
what molecules do not diffuse easily
polar molecules and hydrophilic substances
examples of lipophilic
oxygen, CO2, fatty acids, steroids
How do ions diffuse
use of protein channels
are ion channels integral membrane proteins in a membrane
yes
what is the selectivity for the type of ion
channel diameter
charged
polar surfaces of peptide subunits
Describe membrane potential electrical force
drives positive ions in and negative ions out
Channels are regulated to control what
movement of ions into and out of the cell
channel gating is what
process of opening and closing ion channels
4 types of gated channels
ligand gated (Need ligand such as neurotransmitter)
mechanically gated
always open (K+ and Na+)
voltage gated
what are transporters
integral membrane proteins that mediate movement of ions, polar molecules, and large molecules through a cell
what is mediated transport
movement of substances through a transporter
examples of simple diffusion
O2, CO2, H2O,
examples of facilitated diffuson
GLUT, H2O - AQP, ion channels
What is facilitated diffusion
type of mediated transport
movement of substance through gradient concentration using a transporter
NO ATP
