What is an enzyme?
A biological catalyst that changes the rate of reaction without changing the substances involved
What kind of proteins are enzymes?
Globular proteins
Why can enzymes only catalyse specific reactions?
Their active sites are a specific shape to fit with the substrates
What are anabolic reactions?
Where new chemicals are created
What are catabolic reactions?
Where substances are broken down
What are intracellular enzymes?
They have an effect inside the boundaries of the cell
What are extracellular enzymes?
They have an effect outside the boundaries of the cell
What are the two hypothesis for enzyme action?
Induced fit
Lock and key
Which is the correct hypothesis for enzyme action?
Induced fit
How does the lock and key hypothesis work?
The substrates are an exact fit to the active site so form an enzyme-substrate complex. The active site has an effect on the bonds of the substrate and breaks it apart.
How does the induced fit hypothesis work?
The active site is flexaible and changes shape to accomodate the substrate. When the complex is formed, the active site turns back to it’s original shape which pulls the substrate apart.
What are the two reversible ways enzymes can be inhibited?
Competitive
Non-competitive
What is competitive inhibition?
The inhibitor is a similar shape to the substrate and competes for spaces at the active site. It makes it less likely that an enzyme-substrate complex will form.
What is non-competitive enzyme inhibition?
The inbititor joins to the enzyme and temporarily changes the shape of the active site so an enzyme-substrate complex can’t be formed
What is the irriversable inhibition of enzymes?
The inhibitor makes a permentant covalent bond to one of the groups needed for an enzyme-substrate complex to be formed so nothing else can bind.
