Enzymes Are Proteins

Question 1

What must occur for an enzyme to catalyse a reaction

Answer 1

Must have complementary active site

Must come in physical contact with substrate

Question 2

What are the two ways of measuring ROR

Answer 2

Product formed

Disappearance of reactants

Question 3

Explain how enzymes catalyse reactions using induced fit model

Answer 3

Active site is roughly complementary to substrate

Presence of substrate cause change to tertiary structure causing induced fit, completely complementary now.

Active site is flexible

Question 4

Explain how enzymes lower activation energy

Answer 4

Place strain on bonds holding substrate together when fit is induced

Bonds weaken so less energy is needed to break them.

Question 5

What are the advantages of the induced fit model?

Answer 5

Explains lower AE

Explains how non-competitive inhibitors effect enzyme action.

Question 6

How did the induced fit model come about?

Answer 6

Observations of non-competitive inhibitors altering enzyme activity.

Lock and key model can’t explain observations. Suggests active site is flexible not rigid

Question 7

Explain the lock and key model

Answer 7

Suggests enzyme and substrate fit like a lock and key

Active site is rigid

Question 8

Disadvantages of lock and key model

Answer 8

Doesn’t explain effect of non-competitive inhibitors

Or lowering of AE

Question 9

What is the functional region of an enzyme?

+ when does it become functional?

Answer 9

The induced fit shape of the active site

Caused by change in environment (presence of substrate)

Question 10

Define free energy

Answer 10

Energy available to do work

Question 11

What are the conditions required for the catalysis of a reaction?

Answer 11

Complementary active site and substrate

Present activation energy

Physical contact between enzyme active site and substrate

Question 12

How do you prove enzymes are proteins?

Answer 12

Use biuret reagent

Question 13

Why are enzymes vital for life?

Answer 13

Allow metabolic reactions to occur fast enough for life

Question 14

What is the tertiary of a enzyme like?

Answer 14

Globular

Most globular proteins have metabolic functions

Question 15

What are enzymes also know as?

+ why?

Answer 15

Biological catalysts

Because: 
Made naturally (by body) and catalyses biological reactions

Question 16

Why are enzymes effective at low conc. / doses?

Answer 16

Not used up, can catalyse infinite amounts of reactions

Question 17

Describe non-competitive inhibitors

Answer 17

Inhibitors that bind to another binding site on an enzyme.

Doesn’t compete with substrate

Question 18

Explain how non-competitive inhibitors work

Answer 18

They bond to other binding site other than active site.

Alters shape of active site making it no longer complementary to substrate.

No ES complex can form

Question 19

Describe competitive inhibitors

Answer 19

Bind to active site as has similar shape to substrate. Forms enzyme inhibitor complex

Competes with substrate

Question 20

Explain competitive inhibitors

Answer 20

Bind to active site, blocking substrate from binding. No ES complex can form.

Question 21

What is an enzyme inhibitor?

Answer 21

A molecule that prevents ES complexes from forming

Question 22

What are the two categories of enzyme inhibitors?

Answer 22

Temporary and permanent

Question 23

Give examples of inhibitors

Answer 23

Poison and drugs

Question 24

As enzyme conc doubles what happens to ror?

Answer 24

Doubles

Question 25

What are hydrogen bonds in the secondary structure between?

Answer 25

C==o H——N

Involved in peptide bond

Question 26

What groups are H bonds between in the tertiary structure?

Answer 26

OH O——C==O

Question 27

What’s the difference between the h bonds in the secondary and tertiary structure?

Answer 27

2= atoms invoked in peptide bonds

3= atoms in r group