1) Enzymes are crucial for the reactions involved in the metabolism of food in the human body. Even when conditions vary in the human body, there are enzymes that function to ensure the chemical reactions needed to sustain life take place. In the digestive tract, there is a variation in pH. The stomach can have a pH in the range of 1 to 4, while in the intestines, the pH can vary from 5 to 7.
Describe the tertiary structure of enzymes and explain the chemistry that enables enzymes to function in different parts of the digestive tract. Your response should:
• describe the chemical bonding that enables the tertiary structure to be maintained
• comment on the significance of chemical bonding to the correct functioning of the enzyme
• explain how the enzyme chemically interacts with the substrate. Diagrams may be used to support your answer.
Solution
2) State one factor, other than pH, that would affect the activity of an enzyme. Outline the effect this factor would have on the rate of reaction of the enzyme and explain why
Solution
3) The carbohydrate in a cereal is mainly cellulose with a small amount of starch.
i. Name the monosaccharide unit that makes up both cellulose and starch molecules in the cereal.
ii. The starch in the cereal is composed of approximately 27% amylose and has a glycaemic index (GI) of approximately 70. Give an explanation for the high GI of the starch.
Solution
4) Tristearin, a triglyceride, is the primary fat found in beef and it contains stearic acid as the only fatty acid. 10.0 g of a pure sample of tristearin is completely broken down into its component molecules – glycerol and stearic acid.
M(tristearin) = 890.0 g /mol
M(glycerol) = 92.0 g /mol
This reaction would
A. produce 3.10 g of glycerol.
B. require 0.836 L of hydrogen gas.
C. require 0.0112 mol of water molecules.
D. produce 2.03 × 1022 molecules of stearic acid
Solution