2.1 Enzymes And How They Work

Question 1

Enzymes are…

Answer 1

Complex globular proteins

Question 2

Enzymes have a structure that is…

Answer 2

Roughly spherical, tertiary structure with a very specific shape (active site)

Question 3

Enzymes act as…

Answer 3

Catalysts which speed up the (most of the metabolic) reactions in the body

They also control the rate at which reactions take place

Question 4

Enzymes have an…

Answer 4

Efficient, high TURNOVER - convert many molecules per unit of time

Question 5

Enzymes are produced by…

Answer 5

Ribosomes

Question 6

Each enzyme has its own…

Answer 6

Sequence of amino acids, held in tertiary structure by HYDROGEN BONDS, DISULFIDE BONDS & IONIC BONDS

Question 7

The active site is complementary to the…

Answer 7

Substrate - fits into the active site, making the reaction occur more quickly

Question 8

Enzymes are highly specific:

Answer 8

Because they only it one type f substrate into their active site

Question 9

Enzymes speed up the rate of metabolic reactions without being…

Answer 9

Used up themselves

Question 10

2 types of reaction:

Answer 10

1) Larger molecules broken down into smaller molecules (digestive system)
2) Smaller molecules built up into larger molecules (muscles)

Question 11

For reaction to occur molecules need enough energy to he the reaction started-this is called…

Answer 11

Activation energy - needed to break existing chemical bonds

Question 12

Enzymes lower the…

Answer 12

Activation energy

Question 13

Reactions occur in the body at 37•C, at this temperature most molecules do not have enough kinetic energy to overcome the barrier, so enzymes are needed to…

Answer 13

Lower the activation energy needed for reactions to occur

Question 14

Enzymes lower activation energy by…

Answer 14

Bringing the substrates very close together in the active site - reaction can happen much more easily

Question 15

The lock and key theory is…

Answer 15

Each substrate will fit only one enzyme

Question 16

Some enzymes need…

Answer 16

ACTIVATORS before they will work

Some enzymes can be INHIBITED

Question 17

Competitive inhibitors are…

Answer 17

Complementary to the active site and bind to it.
They reduce the rate by reducing the number of ENZYME SUBSTRATE COMPLEX’s conformed
Active-site directed inhibition

Question 18

Non-competitive inhibitors…

Answer 18

Bind to a site on the enzyme other than the active site
Causing a conformational change in the active site
Reducing the efficiency of ENZYME SUBSTRATE COMPLEX formation
Non-active site directed inhibition

Question 19

Reversible inhibition is…

Answer 19

Inhibitors do not bind permanently to the enzyme their action may be temporary

Question 20

Irreversible inhibitors…

Answer 20

Bind tightly and permanent to the enzyme - enzyme becomes NON-FUNCTIONAL

Question 21

Enzymes have a basic shape that is flexible. It can change so that the active site becomes a close a fit for the substrate, this…

Answer 21

Lowers activation energy needed for the reaction, because the enzyme’s shape changes when substrate present - INDUCED FIT THEORY