B5.1 - Enzymes

Question 1

what are enzymes

Answer 1

proteins that are involved in all metabolic reactions, where they function as biological catalysts

Question 2

describe and explain the enzyme action with reference to:
the active site, enzyme-substrate complex, substrate, and product

Answer 2

-substrate fits into the active site
-forms an enzyme-substrate complex
-bonds break / form
-product is formed
-enzyme waits to be used again with another substrate molecule

Question 3

explain and describe the specificity of enzymes (complementary shape, fit of the active site with the substrate)

Answer 3

each enzyme only binds to 1 type of substrate molecule

active site is complementary in shape to the substrate

Question 4

explain the effect of changes in temperature on enzyme activity (kinetic energy, shape, fit, frequency of effective collisions, denaturation)

Answer 4

-rate of reaction increases as the temperature increases (until the optimum temperature)
–> the molecule’s kinetic energy is increased
–> molecules move around more quickly and collide more often (more effective collisions)
—> more enzyme-substrate complexes are formed
-high temperature causes active site to change shape (enzyme denatures) and the enzyme loses its ability to catalyse the reaction.

Question 5

Explain the effect of changes in pH on enzyme activity (shape, fit, denaturation)

Answer 5

-pH above or below optimum pH affects rate of enzyme action
–> change in pH affects the interactions between the amino acids in a chain and may make the enzyme unfold
–> this makes the active site change shape
–> so substrate can’t attach with the active site so enzyme-substrate complexes can’t be formed
–> more extreme changes make the enzyme denatured