Enzymes

Question 1

What are enzymes?

Answer 1

They are globular proteins with a specific tertiary shape and are usually specific to one reaction.

Question 2

what is the Primary structure of proteins

Answer 2

Order of amino acids

Question 3

what is the Secondary structure of proteins

Answer 3

The way an amino acid folds or coils into an alpha helix or a beta pleated sheet

Question 4

what is the Tertiary structure of proteins

Answer 4

They way it folds the protein to its final shape.

Question 5

What are proteins made up of

Answer 5

Amino acids

Question 6

What is the role of an enzyme

Answer 6

Is to catalyse reactions by interacting with a substrate

Question 7

How do enzymes speed up the rate of reaction

Answer 7

Enzymes lower the activation energy meaning less energy is required to start

Question 8

What is activation energy

Answer 8

The minimum quantity of energy needed to undergo a reaction

Question 9

What are anabolic reactions

Answer 9

The reaction required for growth (building up). The substrate molecules are held closely together in the active site, reducing any repulsion between molecules so the reaction happens faster.

Question 10

What are catabolic reactions

Answer 10

A break down reaction releasing energy (bonds are broken). Strain is put on the bonds in the substrate by the active site. The strain means bonds are weakened and substrate molecules break up easier.

Question 11

What is metabolism

Answer 11

The sum of the different reactions and reaction pathways happening in a cell or organism as a result of the control of enzymes.

Question 12

Lock and key hypothesis

Answer 12

Enzymes are exactly complementary to the shape of the substrate

When they collide they form an enzyme substrate complex and catalyse the reaction forming an enzyme product complex

Question 13

Induced fit hypothesis

Answer 13

Active sites are not exactly complementary but change shape to a specific substrate to become complimentary.

They collide, form an enzyme substrate complex and catalyse forming an enzyme product complex

Question 14

Extracellular enzymes

Answer 14

Enzymes that work outside the cell that made them. E.g. Trypsin is secreted in the pancreas but functions in the Small intestines.

Question 15

Intracellular enzymes

Answer 15

Enzymes that act within the cell the cell that produces it. An example would be catalase which breaks down hydrogen peroxide.

Question 16

Factors that affect the rate of reaction

Answer 16

Temperature - more KE, optimum temp

pH - optimum ph

Enzyme concentration - more enzymes the faster the reaction however it is limited by substrate concentration

Substrate concentration - more substrate molecules more collisions with active site, faster rate of reaction, limited by enzyme concentration

Question 17

What is vmax

Answer 17

The maximum rate of reaction, as a active sites are occupied and no enzyme substrate complexes can be formed

Question 18

What are enzyme inhibitors

Answer 18

Are molecule that prevent enzymes from catalysing reactions, or slows them down. This ensures there is no over production of products.

Question 19

Competitive inhibitor

Answer 19

Has a similar shape to the active site and can bind to it. This blocks the active site and the enzyme cannot carry out its function.

Question 20

Non competitive inhibitor

Answer 20

Has a different shape to the substrate and cannot bind to the active site. Instead it binds to the ALLOSTERIC site. This changes the active site by causing the tertiary structure to change shape.

Question 21

End product inhibition

Answer 21

The end product inhibits an enzyme earlier on in the process. This means the process controls itself.

Question 22

Reversible inhibition

Answer 22

Have weak hydrogen bond or ionic that can be broken

Question 23

Irreversible inhibition

Answer 23

Have string covalent bonds that cannot be broken.

Question 24

Inorganic cofactors

Answer 24

Are inorganic molecules or ions that help the enzyme and substrate to bind together. They are obtained by via the diet as minerals.

Question 25

Example of an inorganic cofactors

Answer 25

The enzyme amylase needs a chloride ion to break down starch which is necessary for the formation of the correctly shaped active site.
Cl⁻

Question 26

Organic cofactors

Answer 26

Are organic molecules that act as carriers moving chemical groups between enzymes and participate in the reaction. They are from vitamins. They are continually recycled

Question 27

Example of organic enzymes

Answer 27

For example vitamin b3 is used to synthesise NAD which is a coenzyme which is responsible for the transfer of hydrogen atoms in respiration.

Another example is vitamin b5 which is used to make a coenzyme that is essential to break down fatty acids and carbohydrates in respiration.

Question 28

Prosthetic group

Answer 28

Are similar to cofactors but are tightly bound to form a permanent feature on the enzyme.

Question 29

Example of prosthetic groups

Answer 29

zinc ions to form part of the enzyme of carbonic anhydrase, which breaks down carbon dioxide.
Zn²⁺

Question 30

How does an enzyme break down a substrate

Answer 30

• The substrate binds to the enzymes active site which it is complementary too.
• It fits with induced fit and forms an enzyme substrate complex.
• Enzyme lowers activation energy and puts strain on the substrate it is breaking down, if it joining it reduces repulsion
• Then the product leaves the active site

Question 31

Example of an extracellular enzyme

Answer 31

Trypsin which is made in the pancreas but travels the small intestine and breaks down proteins into smaller peptide chains

Question 32

Example of an intracellular enzyme

Answer 32

Catalase breaks down hydrogen peroxide in the metabolic pathway into oxygen