Question

Which of the following types of molecules are hydrophilic and therefore excluded from the hydrophobic portion of the phospholipid bilayer?

Select one: a. cholesterol b. peripheral membrane proteins c. integral membrane proteins d. transmembrane proteins e. phospholipids

Answer 1

the molecules which are hydrophilic are-

cholesterol,peripheral membrane proteins,

Peripheral membrane proteins are usually attached to surfaces of integral proteins; therefore, they are on both faces of lipid bilayer. Peripheral membrane proteins interact with the hydrophilic polar head groups of the lipid molecule.

THe hydrophilic hydroxyl group of cholesterol interacts with aqueous environment, whereas the large hydrophobic domain fits between C-tails of lipids. Cholesterol is the central component in several metabolic pathways

Integral membrane proteins, also called intrinsic proteins, have one or more segments that are embedded in the phospholipid bilayer. Most integral proteins contain residues with hydrophobic side chains that interact with fatty acyl groups of the membrane phospholipids, thus anchoring the protein to the membrane.

A transmembrane protein (TP) is a type of integral membrane protein that spans the entirety of the cell membrane. ... The peptide sequence that spans the membrane, or the transmembrane segment, is largely hydrophobic

All of the lipid molecules in cell membranes are amphipathic (or amphiphilic)—that is, they have a hydrophilic (“water-loving”) or polar end and a hydrophobic (“water-fearing”) or nonpolar end. The most abundant membrane lipids are the phospholipids. These have a polar head group and two hydrophobic hydrocarbon tails.