Module 2 - enzymes

Question 1

What are enzymes?

Answer 1

Biological catalyst made of protein, speed up reactions without being used themselves. Catalyse reactions such as respiration, photsynthesis and digestion

Question 2

Lock and Key model

Answer 2

substrate attaches to enzyme’s active site forming an enzyme-substrate complex. Active site is unique to the substrate (complementary) due to tertiary structure
Charged groups distort substrate therefore lower activation energy
Products released and active site is ready to be reused

Question 3

Induced fit hypothesis

Answer 3

The enzyme’s active site is induced or slightly changes to shape and mould around the substrate
This forms enzyme substrate complex, the moulding puts a strain on the bonds so lowers activation energy
Products are then removed and active site returns to the original shape

Question 4

Cofactors

Answer 4

Non-protein substances Some enzymes need inorganic ions to function, they help stabilise structure and could take part in the reaction

Question 5

Coenzymes

Answer 5

Inorganic factors that do not permanently bind but facilitate binding of substrate, many are vitamin derived

Question 6

Activators

Answer 6

Inorganic metal ions that temporarily bind to enzyme to alter active site and make reaction more feasible

Question 7

Prosthetic groups

Answer 7

Permanently attached to enzyme to allow binding

Question 8

Competitive inhibitors

Answer 8

similar structure to substrate and compete for the active site, amount of product formed stays the same but it slows down (lower reaction rate)

Question 9

Non-competitive inhibitors

Answer 9

Bind to the allosteric site and changes shape of the active site, preventing binding of the substrate therefore lowering reaction rate, this tends to be permanent

Question 10

Factors affecting reaction rate of enzymes

Answer 10

Substrate and enzyme concentration, temperature