Question

which of the following can pass through a lipid bilayer(without the assistance of a transport protein)?

select all that apply:

CH3- NH3+

water

H2PO4-

aspartane(an amino acid)

Answer 1

Theoritcal explanation says non-polar molecules can easily pass through lipid bilayer but small uncharged polar molecules can also pass through lipid bilayer like H₂O molecules . But Ions and large molecules of polar molecules can not pass through the lipids.

Methlamine is a polar molecule. Small amount of polar is however easily pass lipid bilayer but charged and large polar molecules cannot pass through lipids bilayer .

H₂PO_4- is neither polar nor non polar molecules , it is an anion of phosphoric acid conjugate. Each lipid molecule contains a hydrophilic region, also called a polar head region, and a hydrophobic region called as nonpolar tail region.The phospholipid molecule's polar head group contains a phosphate group. And di hydrogen phosphate also can soluble dissolve at polar head group of lipid bilayer

aspartane(an amino acid) is a polar molecule with surface area of 119 A⁰² . It is relatively small polar molecule , so it can be soluble in phospholids polar head group of bilayer