GENERAL HISTOLOGY

Detailed explanation-1: -Answer and Explanation: Membranes are components of all of the following except microtubules. Microtubules are structures that are composed of the protein tubulin. These structures are a component of the cytoskeletal network.

Detailed explanation-2: -Final Answer: Proline is not a constituent of the cell membrane.

Detailed explanation-3: -The main components of biological membranes are proteins, lipids, and carbohydrates in variable proportions. Carbohydrates account for less than 10% of the mass of most membranes and are generally bound either to the lipid or protein components.

Detailed explanation-4: -With few exceptions, cellular membranes-including plasma membranes and internal membranes-are made of glycerophospholipids, molecules composed of glycerol, a phosphate group, and two fatty acid chains.