Enzymes

Question 1

Enzymes are

Answer 1

Biological catalyst that lowers activation energy
They are also proteins

Question 2

Protease/peptidase

Answer 2

Breaks peptide bonds within polypeptides

Question 3

Lipase

Answer 3

Breaks ester bonds in triglycerides

Question 4

Amylase

Answer 4

Breaks glycosidic bonds in amylose (and amylopectin)

Question 5

Maltase

Answer 5

Breaks down maltose

Question 6

Why do enzymes lower activation energy

Answer 6

So most molecules can easily get over the activation energy barrier and quickly turn into product

Question 7

Activation energy is

Answer 7

The minimum energy required for a reaction to take place

Question 8

How do enzymes lower activation energy

Answer 8

When a substrate binds to an enzymes active site, an enzyme substrate complex is formed - it’s this that lowers activation energy as it makes them more able to react

Question 9

Induced fit model

Answer 9

The substrate and active site are not complementary.
The active site changes slightly to become complementary to the substrate when it binds.

Question 10

Cellular process that uses enzymes

Answer 10

Respiration
Photosynthesis

Question 11

Process taking place within an organ system that uses enzymes

Answer 11

Digestion

Question 12

4 factors that affect rate of enzyme reactions

Answer 12

Temperature
pH
Enzyme concentration
Substrate concentration

Question 13

factors that affect rate of enzyme reactions
Temperature

Answer 13

As temp increases, rate increases as enzymes and substrate have more kinetic energy so collide more so more E-S complexes made
Above about 40 there is thermal energy to break the weak hydrogen bonds, holding the tertiary structure together, so enzyme denatures

Question 14

pH

Answer 14

At optimum pH, the active site shape is most complimentary to the shape of the substrate. Large changes in PH can cause enzymes, denature and permanently lose their tertiary structure shape. The pH affect the charge of the all groups of the amino acids at the active site so these changes can affect the shape and the charge of the active site so the substrate no longer bind.

Question 15

Enzyme conc

Answer 15

As enzyme concentration increases, the rate of reaction increases as substrate will collide more often with the enzyme to create more ES complexes. At very high enzyme concentration, the amount of substrate, so the rate stops increasing

Question 16

Substrate conc

Answer 16

Add substrate concentration increases rate increases as more substrate can collide with enzymes.
At higher concs enzyme active sites are saturated with substrate so there are few free enzyme molecules so adding more substrate makes no difference.

Question 17

Competitive inhibitor

Answer 17

Similar structure to substrate
Binds to active site
Reduces ES complexes forming

Question 18

Non competitive inhibitors

Answer 18

Different structure to substrate
Doesn’t fit active site
Binds to allosteric site changing shape of active site
So no more ES complexes