Biochemical Reactions In Cell

Question 1

Define enzymes

Answer 1

Biological catalysts that speed up rate of reaction by lowering the Ea without being used up
Example of globular proteins

Question 2

Define Ea

Answer 2

Minimum energy needed to start a reaction

Question 3

Describe lock and key

Answer 3

Lock (enzyme) and key (substrate)
Substrate and Enzyme are specific to eo and E-S complexes will only form if AS shape is complementary to shape of substrate

Question 4

How are enzymes denatured

Answer 4

Extreme changes in temperature and Ph
Affect H- bonds within enzyme and weaken them
Active site shape is altered and no longer complementary

Question 5

Describe induced fit

Answer 5

Enzyme is flexible and changes shape slightly to fit substrate
Puts strain on substrate = lowering Ea as some bond is distorted

Question 6

Induced fit adv

Answer 6

Explains how :
Other molecules affect enzyme activity e.g competitive inhibitor
Explains how Ea is lowered

Question 7

How to measure progress of enzyme controlled reactions

Answer 7

Time taken for products to form
Time taken for substrate to break down

Question 8

Factors affecting enzyme activity

Answer 8

Temp
SA
Pressure
Ph
Concentration

Question 9

How does Temp affect enzyme activity

Answer 9

Increases KE
More rapid collisions
More E-S complexes
Increased rate of reaction

Question 10

How does temp denature enzymes

Answer 10

H bonds break
Changes AS tertiary structure
AS loses specific shape
Enzyme will denature

Question 11

How does pH denature enzymes

Answer 11

Increase in H+ ions
Change in tertiary structure as hydrogen and ionic bonds are disrupted
Changes AS shape
Decreases rate of reaction

Question 12

Test for enzyme activity

Answer 12

Add iodine to spotting tile
2 test tubes one with amalyse and one with starch in test tube at desired temp
Mix amalyse and starch and wait 10 seconds
Add drop of solution to diff spotting tile every 10 seconds
Repeat till iodine stops changing colour
Iodine should change from blue black to orange

Question 13

Define enzyme inhibitors

Answer 13

Substances that directly or indirectly interfere with active site

Question 14

Competitive inhibitor

Answer 14

Similar shape to substrate
Binds and occupies active site
Less E-S formed in given time
Effect can be reduced by increasing substrate concentration

Question 15

Non competitive inhibitor

Answer 15

Attach to site other than AS
This then will alter AS shape
Enzyme can no longer works
Effect Cannot be reduced by increasing substrate conc