Lecture 16- Transport Across Membranes (ch 12_ Flashcards
Lipid molecules are ___ to most water soluble molecules
impermeable
What factors affect diffusion rate of solutes across the membrane?
size and solubility (polar,nonpolar)
Cell membranes form a container in which the inside environment has ___ that controls what comes in and goes out
selective barrier
What are the types of facilitated diffusion?
Passive (high to low concentration of solute) and active (pumps and channels that need energy (some channels dont))
Inner mM of Na+ is __. Outer is ___
Inner is 5 to 15nm, outer is 145; highest solute outside cell
Inner mM of K+ is ___. Outer is __
Inner is 140 nm and outer is 5 nM; highest solute in cell
Inner mM of ca is __ and outer is __
10^-4 inside and 1-2 nm outside
Inner nM of Cl is __ and outer is ___. its job is to?
5-15nm in and 110 nm outside; partially balance sodium outside cell
Whats the resting membrane potential range? what side of membrane is more negative?
-20 to -200 mV; inside
Whats membrane potential
Membrane Potential = Voltage difference across membrane
What causes Cystic fbrosis? and what does this protein normally do to prevent CF
CFTR protein defect; CFTR takes the water and cl out of lungs. if defective, mucus builds up
Distinguish between simple diffusion and facilitated transport
Simple diffusion does not need any channel or transporter
What forces affect transporting solutes through the membrane?
For charged ones, the concentration gradient. For uncharged ones, the gradient and the electrochemical gradient (membrane potential)
What is the difference between transporter and chennels
Transporters change conformations but channels are tunnellike. Both are selective based on size and charge.
Whats resting membrane potential?
Resting membrane potential is the difference ebtween the charges on either side of the membrane. no stimulation. it rests as more negative in the inside
