Enzymes

Question 1

Enzymes lower the what of the reaction is catalyses

Answer 1

The activation energy

Question 2

What is activation energy

Answer 2

The minimum amount of kinetic energy required for chemical reaction to take place.

Question 3

Enzymes ——— a wide range of intra———- and e———- reactions that determine s——— and ———— from cellular to whole organisms level

Answer 3

Catalyse 
Intracellular 
Extracellulair 
Structure 
function

Question 4

What type of protein are enzymes? 2
They are what kind of catalyst?
So What do they regulate?
What determines a proteins specific function?

Answer 4

Tertiary
Globular
Biological catalyst
They regulate biological processes in living organisms
The tertiary structure and protein nature

Question 5

Enzymes in their action lower what?
How do this change the rate of reaction?
How do enzymes do this?

Answer 5

They lower the activation energy
Which in turn increases the rate of reaction.
Enzymes lower activation energy through formation of enzyme-substrate complexes

Question 6

What does is mean that enzymes are specific

Answer 6

Some enzymes only act on a single substrate eg amylase

Some enzymes show specificity for particular chemical bonds eg lipases

Specificity feature of the tertiary structure of an enzyme

Question 7

What about the tertiary structure of an enzyme determines the specificity
4

Answer 7

As the hydrogen ionic and sometimes disulfide bridges determine the shape/ configuration and ELECTROSTATIC charges of the active site

Question 8

Describe the lock and key model

7

Answer 8

Active site is a small region of the enzyme
Only substrates with the complimentary shape of the active site will bind forming an enzyme- substrate complex
Reaction takes place and product released from active site
Enzyme is unchanged at end of reaction

Question 9

What does the induced fit model suggest

Answer 9

The active site can change its shape slightly.
Occurs in presence of correct substrate
Allowing an enzyme- substrate complex to form
The enzyme is flexible and moulds itself around the substrate

Question 10

Does the substrate cause the active site of an enzyme to change chape in the induced fit

Answer 10

Yes the substrate interacts with the active site and causes the enzyme to change shape

Question 11

How does the induced fit make reaction eg condensation more likely

Answer 11

The active site allows two molecules to coke very close together as the substrates interact with the active site and cause it to change shape moulding itself around the substrate making the substrates close together so reaction is more likely

Question 12

For a given concentration of enzyme and increasing substrate concentration what will happen to the rate of reaction

Answer 12

Rate of reaction will increase to a particular point at which the rate reaches a constant maximum rate and plateaus

Question 13

Why would the rate of reaction initially increase

Answer 13

As collisions between the substrate and enzymes become more likely as more substrate is added

Question 14

Why would the rate of reaction level out

Answer 14

As the active site of all the enzymes are occupied by the substrate molecules

Question 15

What is the reaction limited by

Answer 15

The time required for the enzyme - substrate complex to form product and be released from the active site

Question 16

When the active sites are occupied this is also referred to as

Answer 16

Saturated

Question 17

What is the only method to increase the rate of reaction at high substrate concentration

Answer 17

Add more enzymes

Question 18

Why is enzyme less efficient at low temperature

Answer 18

Rate of reaction is slowed due to the reduced kinetic energy so there is less successful collisions between the active site and the substrate so less complexes formed

Question 19

Would does an increase in temp provide for enzymes

Answer 19

More kinetic energy 
More successful collisions 
Between active site and substrate 
More complexes formed 
High rate of reaction 
Increase until the optimum temperature where rate of reaction is highest

Question 20

Where is rate of reaction the highest

Answer 20

At the optimum temperature

Question 21

What happens when the temperature increases above the optimum temperature

Answer 21

Causes the hydrogen bonds to break alternating the shape of the tertiary structures which in turn alters the site of it the active site
So rate of reaction decrease as substrate cannot bind to the altered active as not complimentary and less complexes formed.
Protein denatured permanent and irreversible

Question 22

Enzyme denaturation is also knows as

Answer 22

Loss of catalytic activity of enzyme

Question 23

At low temperature describe the enzyme activity

Answer 23

Low kinetic energy
Slow rate of reaction
Less successful collisions between active site and substrate so less complexes formed
EVENTUALLY all substrate would be converted into product

Question 24

At high temp eg 60 degrees describe enzyme activity

Answer 24

High kinetic energy
Many successful collisions between the active site and substrate
More complexes
High rate of reaction
High temp high kinetic energy break the H bonds enzymes denature change in tertiary structure change in active site
Substrate can no longer bind to altered active site
Reaction stops before all substrate has been converted into product

Question 25

What pH is enzyme activity at the maximum

Answer 25

The optimum pH

Question 26

Do enzymes have a wide pH optimum range?
What can different pH cause?
What does the pH alter? 2
What does this change?

Answer 26

No enzymes have a narrow pH range 
Cause denaturation 
Alter ionic of acidic and basic groups and hydrogen 
Change tertiary structure 
Altered active site 
Substrate no longer complimentary

Question 27

What do enzymes inhibitors do

3

Answer 27

Slow down rate of enzyme catalysed reactions

Question 28

Describe a competitive inhibitor?

How can this inhibition be reduced?

Answer 28

Similar structure 
To SUBSTRATE 
And COMPETES for attachment to active site 
Rate of reaction reduce 
Less successful collisions of AS and S 
So less complexes formed 

Add more substrate

Question 29

What is a non- competitive inhibitor

Answer 29

Nor similar structure to substrate
Combines at position of enzyme other than the active site
Forms a complex
Alters the tertiary structure and alters active site
Substrate cannot attach OR substrate can bind bot no product formed.
Inhibition is completely dependant of inhibitor present