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Question 1

Biological membrane

Answer 1

Biological membranes consist of a double sheet (known as a bilayer) of lipid molecules; lipid bilayer.membrane proteins and sugars are also key components of the structure. Sugars are found on one side of the bilayer only, and are attached by covalent bonds to some lipids and proteins.

Question 2

Intermolecular interactions:

Answer 2

Ionic bridges
Polar interactions
Hydrophobic forces
Calcium bridges
Van der Waals‘ attraction forces = dependent on geometry of molecules
Hydrogen bonds: ~ 20 times weaker than covalent bonds

Question 3

Contemporary theories about the structure of cell membranes:

Answer 3

1925 – Lipid bilayer with assotiated proteins, Gorter & Grendel
1935 - Sandwich-model, Danieli-Davson
1959 – Protein channels through the lipid bilayer, Robertson
1972 – fluidic mosaic model, Singer & Nicolson