Enzymes

Question 1

Role of enzymes

Answer 1

To lower activation energy
Biological catalysts
Allows chemical reaction , for growth, necessary for survival to take place, anabolic
Catabolic, release energy from large organic molecules

Question 2

Effects of substrate concentration

Answer 2

As substrate concentration increases initial rate increases until all active sites are full where the curve levels off.
At the point where the curve levels off is called the V max

Question 3

When more enzymes are added to a solution what happens

Answer 3

V max increases

Question 4

Difference between irreversible and reversible inhibitors

Answer 4

Irreversible inhibitors cannot be removed from the part of the enzyme they r attached to.

Question 5

What is a competitive inhibitor

Answer 5

Molecule with a similar shape to the active site ( but not a perfect fit). It it binds to the enzyme not allowing the substrate molecule to react and breakdown

Question 6

Describe the rate of reaction graph with/without a competitive inhibitor

Answer 6

Without- “r” curve and levels off at v max
With - linear relationship until v max then levels off

The level of inhibition depends on the relative concentration of substrate and inhibitor molecules

Question 7

What are non competitive inhibitors

Answer 7

Inhibitors bind to enzyme , not act active site, this binding causes the active site change shape.
This is almost always non reversible

Question 8

Describe the graph with/without non competitive inhibitors

Answer 8

Without - General “r” curve that levels at v max

With- curve is flat and extremely low, v max is controlled by number of inhibitor molecules

Question 9

What is Q10

Answer 9

Rate of reaction
Temperature coefficient
Found by ROR at (x+10)/ ROR at x

Question 10

What is a co factor

Answer 10

Helps enzymes perform their function by transferring atoms or groups from one reaction to another in a multistep pathway
May form part of the active site
If the cofactor is an organic molecule it is called a co-enzyme
( not a protein)

Question 11

How are Co enzymes used and obtained

Answer 11

By minerals from a persons diet: iron, zinc, calcium, chloride
Vitamins
Example, amylase contains chloride ions needed for active site formation

Question 12

What are prosthetic groups, example

Answer 12

Cofactors that are required by certain proteins to carry out their catabolic function.
They are tightly bound and form a permanent feature of the protein
E.g zinc 2+ forms an important part of carbonic anhydrase

Question 13

Explain the rate of reaction / substrate concentration graph

Answer 13

Linear relationships shows more collisions as substrate concentration increase
More product is formed per second
Curve plateaus meaning the active sites are occupied due to high level of substrate
Enzymes reaching v max
So further addition of substrate does not increase rate of reaction
Enzyme conc becomes the limiting factor

Question 14

Structure of amylose

Answer 14

Alpha glucose molecules 
Alpha glycosidic bonds (c1-c4)
Granular 
H bonds within molecules 
All monomers same orientation

Question 15

How do enzymes breakdown substances

Answer 15

Substrate is nearly complementary to active site
Substrate enters the active site
Induced fit means active site can mould and change shape to be a perfect fit of the substrate
Enzyme substrate complex is formed
Destabilising of bonds then forms enzyme- product complex
Products leave the active site

Question 16

Example of a competitive inhibitor

Answer 16

Penicillin, beta-lactam antibiotics ,

Question 17

Example of enzymes that work in the small intestine

Answer 17

Trypsin, amylase

Question 18

What effect does PH have on enzymes

Answer 18

Change in a curve site
Hydrogen/ ionic bonds affected
Change in tertiary structure
Enzyme may denature

Question 19

Why do enzymes not work effectively at certain temperatures

Answer 19

Below / above optimum temperature
Kinetic energy too low/high of enzyme/substrate
Less chance of enzyme substrate complex formation
Activation energy may be harder to reach

Question 20

How does flexibility help enzymes work faster

Answer 20

Increased chance of substrate entering active site
Easier for active site to change shape
Induced fit will be easier

Question 21

How can structure of enzymes change/differ

Answer 21

Different amino acids
Different feature of secondary/tertiary/quaternary structure. E.g a-helices, different prosthetic groups/co factors/ions/ r groups in different orientations/ polypeptide chain will fold differently

Question 22

How can DNA of enzymes change/differ

Answer 22

Different base sequences
Different ration of bases/nucleotides
Different alleles/gene

Question 23

Anabolic reaction

Answer 23

Responsible for growth of whole organisms

Question 24

Catabolic

Answer 24

Energy released from large organic molecules

Question 25

Role of intracellular enzymes

Answer 25

Synthesis of polymers from monomers requires enzymes

Question 26

Extracellular enzymes

Answer 26

Extracellular enzymes work outside the cell that made them

Enzymes are released from cells to breakdown large Nutrients.

Question 27

End product inhibition

Answer 27

When the product binds to an enzymes active site
negative feedback control mechanism
Stops production of more products
E.g ATP when enough energy has been produced

Question 28

Use of co enzymes

Answer 28

Co-enzymes are small, non-protein molecules that bind to an enzyme at the same time as the substrate to facilitate the reaction and ensure reactions occur in the correct order
They are altered by the reaction and recycled for reuse
They can accept and donate electrons and protons or groups of molecules