Chapter 9: Study Guide and Self-Assessment
There are a staggering variety of molecules present in living materials. The size of these molecules varies from the relatively small to the very large (i.e. high molecular weight), but our focus is obviously on the latter. These biological macromolecules also have an astonishing range of properties and functions. Some, such as the proteins found in skin, hair, nails and claws, are structural. The polysaccharides that make up the chitin that forms the outer, protective layer of insects have a similar function. Other proteins, the enzymes, act as catalysts, promoting the complex chemical processes that are essential to life. The polymers that we call DNA (deoxyribonucleic acid) are equally remarkable, carrying and propagating information – the instructions to build living organisms like you and me. Here we explore some selected natural or biopolymers focusing on those that have large-scale industrial applications, such as the fibrous polymers used to make fabrics and clothes.
Objectives
Upon successfully completing this chapter you should have:
- A broad knowledge of the building blocks of proteins, the amino acids, and how one amino acid differs from another in its structure.
- An understanding that because of restricted rotation around the amide bonds of amino acids and because of steric hindrance factors, there are significant limitations on the conformational freedom of polypeptide chains.
- An understanding of the types of intra- and inter-molecular interactions that occur between monomer units and how these also affects conformation.
- Knowledge of the two principal ordered conformations found in fibrous (and other) proteins, the α-helix and β-sheet.
- An appreciation of the subtle factors that result in the organization and packing of these ordered chains into structures that give a biological material its useful properties.
- A broad knowledge of the basic building blocks of polysaccharides, the sugars, and how one sugar differs from another in its chemical structure.
- As with the proteins, an understanding of the types of ordered structures formed by materials such as cellulose and chitin and how this confers structural integrity in plants and insects.
- An appreciation for how DNA stores information and how its double helical structure allows this information to propagate.
Self-Assessment Questions