2 - BM Enzymes

Question 1

What are enzymes?

Answer 1

Biological catalysts which lower the activation energy needed for metabolic reactions to occur on a cellular and extracellular level.

Question 2

What are enzymes made from?

Answer 2

Enzymes are made from globular 3D proteins with a tertiary structure, they have a specific shape and a specific active site shape which means that only certain substrates with a complimentary shape can bind with it.

Question 3

What are the types of reactions that enzymes can catalyse? ((2))

Answer 3

Anabolic - joining
Catabolic - breaking down

Question 4

What is the induced fit model?

Answer 4

Enzymes fit substrates like a glove, meaning that the shapes are not 100% complimentary but the enzyme moulds to fit the substrate, this tells us that the active site is induced.

Question 5

What is the process of a catalysed reaction under the induced fit model? ((4))

Answer 5

• Enzyme and substrate collide
• Enzyme moulds slightly to fit substrate, has an induced active site
• This moulding weakens the bonds within the substrate as an E-S complex is formed
• The products are then removed and active site returns to normal shape

Question 6

What the the limitations of the lock and key theory? ((4))

Answer 6

• doesn’t explain how the enzyme-substrate complex is stabilised in the transmission state.
• assumes that the enzymes have a rigid structure with a shape that cannot change once bonded with a substrate.
• new research shows that enzymes slightly mould to fit substrate in active site.
• doesn’t describe how multiple substrates can bind to one enzyme.

Question 7

What factors affect enzyme action? ((6))

Answer 7

• Enzyme concentration
• Substrate concentration
• Temperature
• pH
• competitive inhibition
• non-competitive inhibition

Question 8

How does enzyme concentration affect the rate of enzyme action?

Answer 8

• as the enzyme concentration increases, so does the number of active sites available for substrates to collide with successfully
• this means that more enzyme - substrate complexes are formed
• this increases the overall rate of reaction until the concentration of substrates becomes the limiting factor
• this is because there are more enzymes than substrates available to be catalysed

Question 9

How does substrate concentration affect the rate of enzyme action?

Answer 9

• as the substrate concentration increases, so does the rate of reaction
• this is because there are substrate molecules available to successfully collide with the active sites of enzymes, forming more enzyme-substrate complexes
• the rate of reaction slows as the enzyme concentration becomes the limiting factor due to all active sites being occupied