Enzymes

Question 1

What is an enzyme

Answer 1

ENZYMES are biological catalysts.
Catalyst - a substance that speeds up chemical reactions in cells.
- HOW? They lower the activation energy (activation energy- amount of energy required for a reaction to occur)

Speeds up reaction 10 million X.

Question 2

Substrates

Answer 2

The reactants are known as substrates (what is being broken or built)

Enzymes provide a site(space) where substrates can be brought together to react. (like a docking station)

This binding region on the enzyme is called the active site.

Question 3

How do they work?

Answer 3

When substrates are brought together at the active site the form a short-lived enzyme –substrate complex.

Once the reaction has occurred, and the product is formed, the enzyme is released from the complex and restored to its original state.

The enzyme can work again and again.

Question 4

Explanation

Answer 4

IF YOU’RE A “HOW” PERSON (you do not need to know this!)

1. The enzyme may hold the substrates in such a way as to distort the substrate bonds closer to their form in the transition state. This reduces the amount of energy needed to complete the transition.
2. The enzyme may create a charge distribution opposite to that of the transition state. This lowers the energy of the transition state and decreases the activation energy.
3. The enzyme may reduce the reaction entropy ΔS‡ by bringing substrates together in the correct orientation to react.
4. The enzyme may provide a completely different chemical pathway for the reaction. It may form new bonds in the ES complex that would be difficult to form without the enzyme

Question 5

How do Enzymes and Substrates Fit?

Answer 5

One substrate fit into active site of only one enzyme

Lock and Key theory

Question 6

Enzyme Specificity

Answer 6

Enzymes are picky!

Each enzyme catalyzes only one reaction.

For example, there is a specific enzyme that breaks maltose down into 2 glucose molecules.

B/C this is the only reaction this enzyme carries out- called maltase

Many enzymes are named this way replacing suffix with –ase.

Question 7

Name that Enzyme!!!

Answer 7

The enzyme that breaks down maltose is maltase
Using this model name the following:

Bind DNA polymers= _ DNA polymerASE
Breaks down Cellulose= _CellulASE
Produces telomeres= _telomerASE

Question 8

Regulation of Enzymes

Answer 8

Can be affected by:
pH - needs to be stable.
Usually neutral but there are exceptions
Pepsin, digestive enzyme pH 2
Enzymes are active over narrow range of pH.
temperature - enzymes in the human body work best at 37 C - normal body temperature.
Concentration of substrates and enzymes
Inhibitors
Competitive and non-completive

Question 9

CONCENTRATION

Answer 9

Concentration- how much of a substance is present
Substrate Concentration- if there is more of a substance/material then the enzyme can work as fast as possible with the available resources
Listen for example!

Question 10

CONCENTRATION

Answer 10

Concentration- how much of a substance is present

Enzyme Concentration- if there are more enzymes the reaction with occur faster as long as there is enough material

Question 11

INHIBITORS

Answer 11

Inhibitors-a molecule that attaches to the enzyme, not allowing the substrate to attach
Competitive inhibitor-mimic substrate and physically block active site

Noncompetitive inhibitor-attaches to enzyme somewhere other than active site, but changes active site so substrate is unable to fit into active site

Question 12

Enzymes are important in:

Answer 12

1. Regulating chemical pathways.
2. Making materials that the cell needs.
3. Releasing energy.
4. Transferring information.