(i) Which of the following biomolecule is insoluble in water ? Justify. Insulin, Haemoglobin, Keratin. (ii) Draw the Haworth structure for alpha-D-Glucopyranose. (iii) Write chemical reaction to show that glucose contains aldehyde as carbonyl group.

(i) Which of the following biomolecule is insoluble in water ? Justify

1.	(i) Which of the following biomolecule is insoluble in water ? Justify. Insulin, Haemoglobin, Keratin. (ii) Draw the Haworth structure for alpha-D-Glucopyranose. (iii) Write chemical reaction to show that glucose contains aldehyde as carbonyl group.
Answer» Solution :(i) Keratin is insoluble in water because it is a fibrous protein. In such proteins polypeptide chains RUN PARALLEL and are held together by hydrogen and disulphide bonds. (ii) Structure of `alpha`-D-Glucopyranose is given as under: (iii) GLUCOSE REACTS with hydroxylamine to form an oxime. This shows that glucose contains a carbonyl group. Glucose gets oxidised to six-carbon carboxylic ACID, gluconic acid on treatment with a mild oxidising agent like bromine water. This shows that carbonyl group present is an aldehydic group.