Enzymes

Question 1

What is an enzyme?

Answer 1

Globular protein that acts as a biological catalyst which speeds up a chemical reaction by lowing the activation energy. Can be used repeatedly

Question 2

What 5 conditions are need for enzyme action?

Answer 2

free energy of products < substrate
enzyme must have physical contact with the substrate
enzyme must have a active site which fits the substrate.
molecules must collide with enough energy 2 alter the arrangement of atoms
Activation energy

Question 3

Define Activation energy

Answer 3

Minimum amount of energy needed for a reaction to begin

Question 4

Name the structured formed when a enzyme and substrate collide successfully

Answer 4

Enzyme-substrate-complex

Question 5

Describe the induced fit model

Answer 5

enzyme is flexible and becomes a complementary shape to the substrate as it moulds around it.
Changed shape = strains on substrate and distorts the bonds

Question 6

What is the relationship between enzyme and substrate?

Answer 6

complementary

Question 7

Define Anabolic and Catabolic reactions

Answer 7

Anabolic = brings molecules together
Catabolic = as affects bonds so they are easier to break

Question 8

Name the factors affecting enzyme action

Answer 8

pH
Temperature
Enzyme concentration
Substrate concentration

Question 9

How so you find the rate of a reaction on a graph?

Answer 9

rate = gradient

Question 10

Describe the curve on a typical enzyme factor graph

Answer 10

1) Lots of substrate, no product so its easy for substrate to successfully collide with empty active site
2) All as filled @ any given moment, substrate rapidly broken down into products
3) Increase products/ decrease substrate= difficult for substrate to be broken down as products gets in the way
4) Longer 4 substrate to be broken down , rate slows
5) graph flattens out as all the substrate has been used up

Question 11

Describe the induced-fit model of enzyme action

Answer 11

(before reaction) active site not
complementary to/does not fit
substrate;

Shape of active site changes as
substrate binds/as enzymesubstrate complex forms;

Stressing/distorting/bending bonds
(in substrate leading to reaction);

Question 12

How to produce a calibration curve to find unknown concentration?

Answer 12

Make/use  solutions of
known/different concentrations
(and carry out quantitative
Benedict’s test on each);
2. (Use colorimeter to) measure
colour/colorimeter value of each
solution and plot calibration
curve/graph described;
3. Find concentration of sample from
calibration curve;