Enzymes

Question 1

Lock & key hypothesis

Answer 1

enzyme has a specific active site ( lock ) to which a complementary substrate ( key ) fits into exactly ; forming an enzyme substrate complex ; lowering activation energy ; reaction occurs faster ; more products are formed ; enzyme remains unchanged at the end of the reaction

Question 2

Characteristics of enzymes

Answer 2

1) specialised proteins
2) speed up chemical reactions ; catalyst
3) remain chemically unchanged ; can be used over & over ; used in small amounts
4) catalyse reversible reactions in both directions
5) affected by temperature & pH
6) enzyme activity is maximum at optimum temperature & pH
7) denatured by heat, strong acid & strong alkali ; denaturation is irreversible

Question 3

Effect of temperature on enzymes

Answer 3

• increasing temperature to optimum increases kinetic energy of both enzyme & substrate ; they move faster & collide more frequently ; more products are formed
• if temperature increases beyond optimum temperature, enzyme will be denatured and non-functional ; substrate will not bind to active site anymore ; no products formed

Question 4

Effect of pH on enzymes

Answer 4

• when pH fluctuates above/ below optimum, enzyme activity decreases
• if pH increases beyond optimum, enzyme will be denatured and substrate will not fit into active site anymore.