Biological molecules: Practice Questions

Which type of chemical bond is primarily responsible for maintaining the secondary structure of a protein, such as an \(\alpha\)-helix or a \(\beta\)-pleated sheet?

What is the chemical formula for the carboxyl group found in all amino acids and fatty acids?

An unsaturated fatty acid differs from a saturated fatty acid because the R-group of an unsaturated fatty acid:

Identify the disaccharide that is formed by the condensation of an \(\alpha\)-glucose molecule and a fructose molecule.

To test for the presence of a non-reducing sugar such as sucrose, what is the correct sequence of steps after an initial Benedict’s test remains blue?

Identify the monomer that is the building block of all proteins and name the specific chemical bond that joins these monomers together during a condensation reaction.

The diagram shows two isomers of glucose, X and Y. Identify which molecule represents \(\beta\)-glucose and explain why the positions of the hydroxyl (-OH) groups on carbon-1 and carbon-4 require alternate molecules to be rotated by \(180^{\circ}\) during the formation of a glycosidic bond.

Starch and cellulose are both polysaccharides found in plant cells, yet they perform very different functions.
a) Describe the structural differences between α-glucose and β-glucose.
b) Explain how the structure of cellulose molecules allows them to form strong fibres in plant cell walls.
c) A student is given a solution of unknown carbohydrate. Describe the biochemical tests the student would perform to identify if the solution contains starch and if it contains a non-reducing sugar.