bio - cell membrane

[joonkimdds]

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which of the following would most likely move through the lipid bilayer of a cell membrane most easily?
a. carbon dioxide
b) glucose
c. potassium ion
d) startch
e) amino acid

could u explain why a) carbon dioxide is the answer?

 

[RT0223]

b & d & e --- too big
c --- that's why we have the Na+/K+ pump

 

[Ex_EE]

CO2 is nonpolar, no net dipole, so therefore it passes through the nonpolar region by simple diffusion.

 

[djeffreyt]

b & d & e --- too big
c --- that's why we have the Na+/K+ pump

the answer is A...he just said that in his post.

But she or he is correct that B D E are all too large to move simply through a membrane. THe stuff that moves easily through a membrane are nonpolar and small. Glucose is polar and of decent size, Starch is like a bigger string of glucose, and amino acids are also polar. Potassium ions are charged and thus polarized, so they are off the list too. CO2 isn't polar and small enough to move through without a carrier.

 

[RT0223]

the answer is A...he just said that in his post.

But she or he is correct that B D E are all too large to move simply through a membrane. THe stuff that moves easily through a membrane are nonpolar and small. Glucose is polar and of decent size, Starch is like a bigger string of glucose, and amino acids are also polar. Potassium ions are charged and thus polarized, so they are off the list too. CO2 isn't polar and small enough to move through without a carrier.

That's why I didn't say anything about A cuz A is the ans. I only point out the ones that are wrong.

 

[djeffreyt]

oh, I thought you were saying the answer was c and explaining it...my bad