Factors affecting Enzyme Actvity

Question 1

How does pH affect Enzyme Activity?

Answer 1

• Enzymes are denatured at extremes of pH
• Hydrogen and ionic bonds hold the tertiary structure of the protein
• The breaking of bonds alters the shape of the active site, which means enzyme-substrate complexes form less easily
• enzyme-substrate complexes can no longer form at all
• complete denaturation of the enzyme has occurred

Question 2

How does Temperature affect Enzyme Activity? - LOW TEMPERATURE

Answer 2

• Enzymes have a specific optimum temperature
• lower temperatures either prevent reactions from proceeding or slow them down
• less kinetic energy of molecules
• low frequency of successful collisions
• less frequent enzyme-substrate complex formation
• Substrates and enzymes also collide with less energy, making it less likely for bonds to be formed or broken.

Question 3

How does Temperature affect Enzyme Activity? - HIGH TEMPERATURE

Answer 3

• cause reactions to speed up
• Molecules move more quickly as they have more kinetic energy
• Increased kinetic energy results in a higher frequency of successful collisions between substrate molecules and the active sites of the enzymes which leads to more frequent enzyme-substrate complex formation
• Substrates and enzymes also collide with more energy, making it more likely for bonds to be formed or broken (allowing the reaction to occur)

Question 4

How does Temperature affect Enzyme Activity? - DENATURATION

Answer 4

• The increased kinetic energy and vibration of the enzyme molecules puts a strain on them -> weaker hydrogen and ionic bonds
• breaking of bonds
• The active site is permanently damaged and its shape is no longer complementary to the substrate, preventing the substrate from binding
• Denaturation has occurred if the substrate can no longer bind

Question 5

Temperature coefficient

Answer 5

• The temperature coefficient for a biological reaction is the ratio between the rates of that reaction at two different temperatures
• For most enzyme-catalysed reactions the rate of the reaction doubles for every 10 °C increase in temperature
• The temperature coefficient (Q) for a reaction that follows this pattern is: Q₁₀ = 2

Question 6

ENZYME CONCENTRATION

Question 7

SUBSTRATE CONCENTRATION