Science at a Distance

Physical Structure

Lecture notes - Part 1 Lecture notes - Part 3

Lecture Notes

a check up

Use this section to check up on the accuracy of your lecture notes. Make sure that you have written down the following definitions, explanations and important concepts in your notes.

Physical Structure - Part Two

Polymers and Polymerization

Polymers are large molecules made by joining smaller units together in long chains. The chemical and physical properties of the polymer are very different to that of the constituent smaller units.


There are four classes of biopolymers found in and used by living cells; lipids, polysaccharides, proteins and nucleic acids. All are polymers of smaller monomer units joined together.

Hydrocarbons and Fatty Acids

Hydrocarbons are biopolymers. They are long chains of carbon atoms each with two hydrogen atoms. Fatty acids are hydrocarbon chains with an organic acid group (-COOH) at one end.


There are five main groups of compounds commonly termed lipids; fats, oils, phospholipids waxes, and steroids. All but one contain either hydrocarbon chains or fatty acids in combination with other groups or molecules.

Roles for Lipids

Lipids play a variety of roles in living cells and living organisms. Generally, lipids serve as energy storage molecules, waterproof coverings and highly flexible barriers or boundaries between cells are their surroundings.

Carbohydrates and Sugars

The term carbohydrate means carbon joined with water and is a general term for a wide range of substances which broadly consist of molecules having one carbon atom for every two hydrogen atoms and one oxygen atom (C:H:O, 1:2:1). The simplest forms of common carbohydrate are the sugars.

Roles for Polysaccharides

Polysaccharides contain a reasonable amount of energy and are often used by plants as their fuel reserves, but other polysaccharides function as strong building materials (in plant cell walls) and as recognition molecules on cell surfaces.

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Lecture Notes - Part 1 Lecture Notes - Part 3
Physical Structure

Science at a Distance
© 1997, 1998, 1999, 2000, Professor John Blamire