Which of the following statements describes integral membrane proteins? i. they protect the contents of the cell from chaotropic agents such as urea. ii. they are easily dissociated from the membrane by changes in ph or high salt concentration. iii. they are held tightly in place by hydrophobic effects between the membrane and hydrophobic amino acids. a) i, ii, iiib) i, iiic) id) iie) iii

E (III)

Explanation:

Several peripheral membrane proteins are tethered to the membranes by covalent linkages with the membrane lipids, .

Example is the one involving phosphotidyl inositol. The fatty acid groups of phosphotidyl inositol are firmly inserted into the lipid membrane thus anchoring the protein.

Membrane proteins have hydrophobic regions that passes through the membrane and interact with the hydrophobic tails of the lipid molecules in the core of the bilayer, since the lipids are inserted into the hydrophobic core, the proteins are firmly anchored.