Membrane Structure and Function?

Question

Which of the following statements about membrane structure and function is false?
a. Diffusion, osmosis, and facilitated diffusion do not require any direct energy input from the cell.
b. Special membrane proteins can cotransport two solutes by coupling diffusion down one concentration gradient to transport against another concentration gradient.
c. Diffusion of gases is faster in air than across biological membranes.
d. The types of proteins that are exposed on one side of a membrane are nearly identical to those exposed on the other side of the same membrane.

Answer 1

d is false (see freeze fracture of membranes)

Answer 2

There are somewhat 3 styles of cellular membrane proteins: linked ones (loosely linked to the membrane), embeded ones (one section is anchored to the membrane) and transmembrane proteins (one section is interior the cellular one interior the membrane and one protruding) the cellular membrane is a charged lipid bilayer with the unfavorable and watery section dealing with out - so any part of a protein beeing interior a membrane ought to be negatively charged and/or be lipophillic. The domain names of proteins in a membrane or crossing it tend to be alpha helices. applications are manifold - for transmembrane proteins the main hardship-loose are channel or receptor. Channel delivery molecules around the membrane and can desire to be gated to close the cellular - in many cases a kit of helices making a small pore. receptors attain in the time of yet make no beginning interior the cellular wall - the perfom a structural substitute upon binding of a ligand which finally ends up in activation interior the cellular. membrane sure proteins are in many cases places of synthesis or are assisting transmembrane proteins (an occasion could be G- protein coupled receptors) - somewhat the comparable is going for membrane linked proteins with them beeing able to cycle from and to the membranes (an occasion may be the SecA transporter) easy platforms: linked and sure proteines have in many cases a catalytic midsection the place they convert ATP or GTP while transmembrane proteins lack those