(a(i))[1]
Name the process by which ions move across the membrane through channel proteins.
(a(ii))[2]
Explain why ions need a channel protein in order to pass across a cell membrane.
(b(i))[1]
Name the protein structural level that is present when five polypeptide chains form the protein.
(b(ii))[1]
The region labelled C in Fig. 2.1 represents another level of protein structure. Name this level.
(c)[3]
Channel proteins are transmembrane proteins. Their polypeptides are held together and also interact with phospholipids in the membrane. Suggest how the polypeptides are held together and suggest how they interact with phospholipids.