Enzymes

Question 1

What do enzymes do?

Answer 1

They are biological catalysts that reduce the activation energy needed to start a reaction

Question 2

Stages of reactions using enzymes

Answer 2

Substrate fits into a specific enzyme’s active site forming an enzyme-substrate complex.
They have complementary shapes.
Once reaction is complete there is a enzyme-product complex
The products are released
Enzyme is unchanged

Question 3

What is the lock and key hypothesis?

Answer 3

Substrate fits into the enzyme. It is precisely the correct shape to fit into the active site

Question 4

What is the induced fit hypothesis?

Answer 4

As the substrate binds to the active site, the active site changes shape slightly to fit the substrate more closely.

Question 5

What are the 2 categories of enzyme?

Answer 5

Intracellular

Extracellular

Question 6

Describe intracellular enzymes

Answer 6

Work inside the cell

For example, the enzymes in lysosomes

Question 7

Describe extracellular enzymes

Answer 7

Work outside the cell
For example, in digestion the enzymes in the stomach (doesn’t happen in the cells)
And
fungal hyphae (fruit becoming furry)

Question 8

How enzymes break things up

Answer 8

Strain the bonds between them

Question 9

How enzymes help join things together

Answer 9

Hold reactants together in correct orientation to help make the bonds.

Question 10

What are inhibitors?

Answer 10

Substances that affect enzymes.

Slow down the rate of enzyme-controlled reactions.

Question 11

What are competitive inhibitors?

Answer 11

They are complementary to the enzymes active site.

Competitive because both the CI and the substrate can fit into the active site (they have SIMILAR shapes)

Question 12

How do competitive inhibitors work?

Answer 12

CI blocks active site so enzyme-substrate complex can’t be formed, reducing the rate of reaction

Question 13

Can you overcome competitive inhibitors?

Answer 13

Yes, by increasing substrate concentration.
Increases the chance of the substrate binding with the active site before the CI.
It is REVERSIBLE

Question 14

How do non competitive inhibitors work?

Answer 14

Bind to Allosteric site, this changed the shape of the enzymes active site so an enzyme substrate complex can’t be formed, reducing the rate of reaction.
Substrate and NCI have different shapes.

Question 15

Is it possible to overcome non competitive inhibitors?

Answer 15

No, enzyme is permanently changed so substrates, no matter how many there are, can bind to the active site.
It is IRREVERSIBLE.

Question 16

What is the equation for the temperature coefficient?

Answer 16

Rate of reaction at T+10 degrees celsius

Rate of reaction at T degrees celsius`

Question 17

What is the normal temperature coefficient for enzyme reactions?

Answer 17

2

Question 18

`What are cofactors?

Answer 18

An inorganic ion that increases the activity of an enzyme

Question 19

What is a coenzyme?

Answer 19

Organic molecule required for enzyme function

Question 20

What is a prosthetic group?

Answer 20

Permanently bound to the enzyme, required for enzyme function.

Question 21

What is product inhibition?

Answer 21

When the product made from an enzyme controlled reaction acts as an inhibitor
Can be good - stop too much being made - waste

Question 22

What is the product, substrate and cofactor of amylase?

Answer 22

Glucose/maltose
Starch
Calcium ions

Question 23

When enzymes build larger molecules from smaller ones what is it called?

Answer 23

An anabolic enzymatic reaction

Question 24

How effective is the Software that predicts the 3D shape of a protein based on it’s amino acid sequence is at discovering the function of the enzyme

Answer 24

Tertiary structure determines shape of active site which relates to the function.
Protein folding is highly complex and there can be multiple solutions.
Therefore, function can be narrowed down but not fully predicted.

Question 25

What is a common source of coenzymes for humans?

Answer 25

Vitamins

Question 26

Similarity between cofactors and prosthetic groups?

Answer 26

Both bind to an enzyme to make formation of the enzyme substrate complex easier

Question 27

Difference between cofactor and prosthetic groups?

Answer 27

Prosthetic groups are permanently attached to the enzyme while cofactors can move or attach to the substrate