Biological Molecules - Enzymes

Question 1

how do enzymes work, what is the theory called.

Answer 1

they work using the collision theory, colliding with the substrates, each collision results in a reaction.

Question 2

what types of proteins are enzymes, and what is unique about them.

Answer 2

they are globular proteins. these proteins are folded to create a uniquely shaped groove or pocket which binds to the substrate. to form an enzyme-substrate complex.

Question 3

list the 2 main models of enzyme action

Answer 3

1. lock and key
2. induced fit.

Question 4

Describe the lock and Key model of enzymes.

Answer 4

1. substrate collides with the enzyme
2. substrates complemantry shapes allows it to bind to the enzymes active site - attractions are formed - and the enzyme substrate complex is a perfect fit.
3. the enzyme converts the substrates into product
4. attractions break and the product is released.

• this model explains why enzymes show high specificty.

Question 5

Describe the induced fit model

Answer 5

1. the substrate collides with the enzyme
2. the enzyme changes the active site shape to fit the substrate.
3. enzymes convert the substrate into product.
4. attractions are broken and product is released.
5. enzyme changes back to original shape.

Question 6

explain the significance of the induced fit model. what does it explain.

Answer 6

it explains why some enzymes show broader specificity eg - lipase.
it also explains how catalyses works by placing stress on bonds.

Question 7

what conditions are essential for enzyme activity.

Answer 7

they have an optimum pH and temperature that they work at. at high temps or pH’s away from the optimum, the enzymes get denatured.

Question 8

explain how denaturing of enzymes occurs

Answer 8

it occurs when bonds in the tertiary structure are broken, changing the shape of the active site - reducing the ability to form the enzyme substrate complexs - so reaction rate decreases.

Question 9

what are inhibitors

Answer 9

they are molecules that bind to enzymes and reduce their activity.

Question 10

describe competitive inhibition

Answer 10

when the molecule competes with the substrate. they block the enzymes active sites, so not enough enzymes for the substrates.
increasing substrate concentration reduces the effect of the inhibitor.

Question 11

describe non-competitive inhibition

Answer 11

these molecules don’t directly compete with the substrate for the enzymes active site, they bind to a site other than active site on the enzyme, this changes the shape of the active site. increasing substrate concentration won’t effect the rate of reaction.