Exam 2 Material Flashcards
Membranes are ________ Barriers
Selective
What two things does the diffusion of molecules across a synthetic lipid bilayer depend on?
Size and Solubility (in lipid)
True or False: Charged molecules always diffuse across the lipid bilayer no matter how small
False: charged molecules Rarely diffuse across
What type of molecules diffuse quickly and easily across the lipid bilayer?
Small Nonpolar Molecules
examples of small nonpolar molecules
O2, CO2, N2, Steroid Hormones
What type of semi-permeable molecules moves a bit slower than small nonpolar molecules?
Small uncharged polar molecules
examples of small uncharged polar molecules
H2O, Ethanol, Glycerol
What molecules cannot easily cross the lipid bilayer?
Large uncharged polar molecules
examples of large uncharged polar molecules
amino acids, glucose, nucleosides
What type of molecule cannot cross the lipid bilayer on their own?
ions
examples of ions
H+, Na+, K+, Ca2+, Cl-, Mg2+, HCO3-
What is responsible for the selective transfer of water-soluble molecules across the membrane?
Membrane transport proteins
Cells maintain a _______ inside/outside concentrations of ____/_________ as they are impenetrable through the lipid bilayer
different, ions/charged molecules
Active Transport
Investing energy
What uses active transport?
Transporters (pumps)
Passive Transport
Without investing energy
What uses passive transport?
Transports and ion channels (Channel Protein)
Transporters
may be passive or active (pumps)
Ion Channels are __________
Passive Only
Passive Transport: uncharged molecules
for an uncharged molecule like glucose, the Direction of transport is dependent solely on Concentration
3 types of Active Transport Pumps
- Gradient-Driven Pump
- ATP-Driven Pump
- Light-Driven Pump
The Sodium-Potassium Pump is a type of __________
ATP Driven Pump
Sodium-Potassium Pump
3 Na out, 2 K in
The sodium-potassium pump is used to
establish membrane potential
What does the Sodium-Potassium pump help maintain?
osmotic balance
