2.1.4 Enzymes

Question 1

What are enzymes called?

Answer 1

Biological catalysts

Question 2

Enzymes can be ___ or ___

Answer 2

Intracellular or extracellular

Question 3

Structure of an enzyme

Answer 3

Active site which specific substrates bind to to create an enzyme-substrate complex

Question 4

What can change the shape of an active site?

Answer 4

pH and temperature changes.

Question 5

What is the lock and key hypothesis?

Answer 5

The idea that the enzyme has a fixed shape and only the right substrate will fit into the active site.

Question 6

What is the induced fit hypothesis?

Answer 6

When the substrate molecule fits into the enzymes active site, the active site undergoes a conformational change in its shape fit itself around the substrate molecule, enabling a tighter fit.

Question 7

Factors that affect enzyme activity?

Answer 7

-pH
-Temperature
-Enzyme concentration
-Substrate concentration

Question 8

What is the affect of a pH on enzyme activity?

Answer 8

All enzymes have an optimum pH which they work best at. At extreme pH’s enzymes are denatured. Below and above an enzymes optimum pH, solutions with an excess of H+ ions and OH- ions can cause these bonds to brisk so enzyme substrate complexes form les easily.

Question 9

What can we use to investigate the effect of different pH’s on enzyme activity?

Answer 9

Buffer soloutions

Question 10

What is the affect of low temperature on enzyme activity?

Answer 10

Lower temperatures prevent reactions from proceeding or slow the down as the molecules will have less kinetic energy. Less kinetic energy results in fewer successful collisions so fewer enzyme substrate complexes. Substrates and enzymes will also collide with less energy.

Question 11

What is the affect of high temperatures on enzyme activity?

Answer 11

Higher temperatures causes molecules to have more kinetic energy so they will move faster and increase the success of collisions so result in more enzyme substrate complexes.

Question 12

What is the temperature coefficent?

Answer 12

Measure of how much reaction rate increases with a 10 degree temp increase.

Question 13

What is the affect of enzyme concentration on enzyme activity?

Answer 13

The higher the enzyme concentration, the greater the number of actor sites available for enzyme substrate complex formation. As long as there are sufficient substrates available, the rate of reaction increases.

Question 14

What is the affect of substrate concentration on enzyme activity?

Answer 14

The greater the substrate concentration, the higher the rate of reaction. As the number of substrate molecules increases,the likelihood of enzyme substrate compels formation increases. If all active sites are saturated,any further increase in substrate concentration will not increase reaction rate.

Question 15

What is activation energy?

Answer 15

the minimum amount of energy needed to start a chemical reaction

Question 16

How do enzymes reduce the amount of activation energy needed?

Answer 16

They reduce the stability of bonds in the reactants so the reaction increases.

Question 17

What are the two types of reversible inhibitors?

Answer 17

Competitive and non competitive.

Question 18

What is a competitive inhibitor?

Answer 18

Have a similar shape to a substrate molecule and so therefore compete with the substrate for the active site.

Question 19

What is a non competitive inhibitor?

Answer 19

Binds to the enzyme at an alternative site (not the active site) which alters the shape of the active site so prevents the substrate from binding with it.

Question 20

What is the affect of inhibitors on enzyme activity?

Answer 20

They slow enzyme activity down or stop it.

Question 21

What are non reversible inhibirors?

Answer 21

Occupy the active site forever, permenant.
Covalent bonds form between the enzyme and the inhibitor.

Question 22

What is the result of a non reversible inhibitor?

Answer 22

The enzyme will be completely inactivated.

Question 23

Non reversible inhibitors can also be called ____

Answer 23

Metabolic poisions.

Question 24

What is a co-factor?

Answer 24

An inorganic ion or nonprotein organic molecule at the active site that makes the enzyme active.

Question 25

What are coenzymes?

Answer 25

Organic cofactors.

Question 26

What are prosthetic groups?

Answer 26

Similar to cofactors but they are bound to the enzyme rather than being separate molecules or atoms.