Outline7 marksChallenge
A newly discovered toxin, toxA, binds specifically to a membrane protein that allows the passive movement of K⁺ ions down their concentration gradient. Cells exposed to toxA show a significant reduction in K⁺ uptake, but their ability to bind a signalling ligand (hormone) remains unchanged.
(a) Outline the fluid mosaic model of membrane structure, with reference to:
- the role of phospholipids and cholesterol in the bilayer;
- the arrangement and roles of glycolipids and glycoproteins.
(b) Using the information about toxA, explain the functional difference between carrier proteins and channel proteins.