Name four small nonpolar molecules that readily diffuse across lipid bilayer?
Oxygen, carbon dioxide, Nitrogen and benzene.
Name two common uncharged polar molecuels that cross the libpid bilayers.
Water and ethanol.
Example of common large uncharged polar ions that cannot pass through lipid bilayers without having
Glucose, amino acids, sodium, potassium, hyrogen and chlorine.
Why is the inside of the cell have a less positive charge than the outside.
Because the ions on the outside of the cell (Cl-, Na+ and Ca ++) combine to have a bigger positive charge.
What is a transporter?
Protein complex that allows passage of lg molecules and ions through lipid bilayer. It tansports it by changing its shape.
What is a channel?
protein complex that allows small ion molecules to pass through lipid bilayer by hydrophilic pores in the membrane.
(facilitated diffusion). Molecules move down their concentration gradient, from high to low concentration. Does not require energy.
Molecules move against their concentration gradient and requires energy to move through the "pumps".
The two states of Passive Transport.
State A-binding sites on outside of membrane exposed. State B- binding sites exposed to the inside of membrane
Three methods of active transport.
Coupled transporters, ATP-driven pumps and Light-driven pumps.
molecules move down concentration gradient as others move up concentration gradient.
Transport molecules down concentration gradient by ATP hydrolysis.
Couples transport of molecules against their concentration gradient with input from light.
Symport Vs Antiport
Symport has both molecules transported in same direction across membrane. Antiport has them moving in opposite directions.
SGLT1 vs SGLT2
Sodium-glucose symport. SGLT1 glucose absorption in small intestine. SGLT2 glucose reabsorption in the kidney. Na down  glucose agains .
Where do you find sodium-glucose symport transporters?
plasma membrane epithelial cells of sm. intestine and proximal tubule of the nephron.
Two glucose transporters of Enterocytes.
Sodium-dependent glucose transporter (apical surface). Passive glucose transporter (basal surface).
sodium, calcium exchanger.
In plasma membrane, uses energy of sodium moving down  to move calcium out of cell against 
How to regulate sodium and potassium concentrations
By sodium and potassium pumps. . Responsible for 1/3 of cell energy expenditure.
Value of sodium and potassium transfered during 1 cycle of Na+-K+ pump.
3 Na+ out of cell and 2 K+ into cell per cycle.
Significance of sodium-potassium pumps.
maintains resting potential of cell by active transport.
Two mechanisms that keep calcium  low inside the cell.
Sodium-calcium exchanger and Calcium pumps. Both are active transport (Na+ uses the gradients).
Significance of the regulation of Calcium concentration inside cell.
Calcium is needed as a second messenger in many signal transduction pathways.
Three types of gated ion channels.
voltage-gated, ligand-gated and Stress-gated.
Where are voltage-gated ion channels
nerve cells (mostly), muscle cells and egg cells.
Significance of voltage-gated Sodium and potassium channels
Responsible for creation and propagation(NA+) and repolarization (K+) of action potential .
Significance of voltage-gated Calcium channels.
Muscle excitation and contraction.
What do ligan-gated ion channels do with chemical signals and what neurotransmitter is needed.
changes it to an electrical signal. Acetylcholine.
Where do you find Ligand-gated ion channels?
Surface of some neurons and the postsynaptic side of neruromuscular junction.
How does the cell change its membrane potential in postsynaptic cells.
Response to action potential, Voltage-gated ion channels open, increase in Ca2+ induces release Acetylcholine which binds to ligand-gated channels.
Where is an example of stress-gated ion channels.