Enzyme

Question 1

What is a catalyst

Answer 1

A substance that can speed up a chemical reaction without itself being chemically changed at the end of the reaction

Question 2

What are enzymes

Answer 2

They are biological catalysts that speed up the rate of chemical reactions without itself being chemically changed at the end of the reaction

Question 3

What is the Lock-and-key hypothesis

Answer 3

It describes how an enzyme will only act on a specific substance called the substrate

Question 4

The mode of action of enzymes

Answer 4

1. There are depressions on an enzyme that form the active site
2. The specific substrate binds with the enzyme’s active site as it has a shape complementary to the active site
3. When the substrate and enzyme’s active site bind together, they form the enzyme-substrate complex
4. A chemical reaction occurs on the substrate molecule, causing the products formed to leave the enzyme’s active site
5. The enzyme itself remains chemically unchanged and the active site is available for another substrate to bind to it

Question 5

What are the characteristics of enzymes

Answer 5

1. They speed up chemical reaction by lowering the activation energy
2. They are specific in action as only a substrate that has a shape complementary to the enzyme’s active site will bind with it and cause a chemical reaction
3. They are required in minute quantities and remain chemically unchanged at the end of the reaction as enzymes can be reused
4. They are affected by temperatures
   ( At low temperatures, kinetic energy of molecules is low the chances of effective collision between enzyme and substrate molecules is very low)

(Enzyme activity is fastest at optimum temperature)

(As temperature increases above the optimum temperature, enzymes start to denature and enzyme activity decreases rapidly)

5. They are affected by pH (Extreme acidity or alkalinity of a solution will cause enzymes to denature)

Question 6

Why does temperature and pH affect enzymes’ ability to catalyze reactions

Answer 6

High temperature and extreme acidity and alkalinity causes the enzyme to denature and change its 3D structure, causing the loss of its active sites causing the enzymes to be unable to act on the substrate