Cell Membrane

Question 1

Structure of the membrane

Answer 1

The membrane is a known as a fluid-mosaic model.

phospholipids, glycolipids, glycoproteins, extrinsic protein, intrinsic protein and cholesterol

Question 2

Fluid-Mosaic Model

Answer 2

The model of the structure is called fluid-mosaic because:
Fluid - The individual phospholipid molecules can move within a layer relative to one another
Mosaic - The proteins embedded in the bilayer vary in shape, size and pattern

Question 3

Cholesterol

Answer 3

Cholesterol occurs in the membranes of animal cells, between the phospholipid molecules, making the membrane more rigid and stable

Question 4

Glycoproteins and Glycolipids

Answer 4

Glycoproteins and glycolipids are found in the outer layer of the membrane. The carbohydrate layer around the membrane is called the glycocalyx. Some molecules in the glycocalyx have roles as hormone receptors or in cell-to-cell

Question 5

Permeability of the Membrane

Answer 5

Lipid-soluble substances, eg vitamin A, and small molecules, eg oxygen and carbon dioxide dissolve in the phospholipid and diffuse across the membrane. The phospholipid layer is hydrophilic so lipid-soluble molecules move through the cell membrane more easily than water-soluble substances
Water-soluble substances, eg glucose, polar molecules and ions cannot readily diffuse through the phospholipids and must pass through intrinsic protein molecules, which form water-filled channels across the membrane. As a result, the cell-surface membrane is selectively permeable to water and some solutes