Enzymes 1&2

Question 1

How are enzymes different from chemicals?

Answer 1

Catalyse very high reaction rates
Regulated by homeostasis
Very specific

Question 2

Ribozyme

Answer 2

Made from RNA not protein

Question 3

Cofactor

Answer 3

Non protein component required for activity

Question 4

Coenzyme

Answer 4

Complex organic molecule made from vitamins eg FAD

Question 5

Prosthetic group

Answer 5

Cofactor covalently bound to enzyme

Question 6

Apoenzyme

Answer 6

Protein component of enzyme containing cofactor

Question 7

Holoenzyme

Answer 7

Whole enzyme apoenzyme + coenzyme

Question 8

Substrate

Answer 8

Molecule added on by enzyme

Question 9

Active site

Answer 9

Part of enzyme which substrate binds

Question 10

How do enzymes reduce Ea

Answer 10

Entropy reduction
Desolvation
Induced fit

Question 11

Entropy reduction

Answer 11

Molecules randomly come together

Enzyme forces them to collide

Question 12

Desolvation

Answer 12

Shield of stable water removed

Weak bonds replace these

Question 13

Km

Answer 13

Substrate concentration at which the initial reaction rate is half of the maximum reaction rate

Question 14

What does a large km mean?

Answer 14

Unstable

More reversing back

Question 15

Vmax

Answer 15

How fast a reaction proceeds when enzyme saturated with substrate

Question 16

Isoenzyme

Answer 16

Different proteins but catalyse the same reaction

Question 17

Glucokinase

Answer 17

Found in liver

High km and vmax

Question 18

Hexokinase

Answer 18

Found in other tissues

Low km and vmax

Question 19

2 ternary examples

Answer 19

Ordered eg pyruvate=>lactate

Random eg creatine=>phosphocreatine

Question 20

No ternary examples

Answer 20

Amino acid=>keto acid

Ping pong ball

Question 21

Competitive inhibitors (km and Vmax)

Answer 21

Increased km and unchanged Vmax

Question 22

Non competitive inhibitors (km and vmax)

Answer 22

Unchanged km and decreased v max

Question 23

Transition state analogue

Answer 23

Make an inhibitor that mimics transition state

Question 24

Catalytic antibodies

Answer 24

Antibody with a specific to transition state molecule

Question 25

Concerted model

Answer 25

Only 2 conformations

Switch between each

Question 26

Sequential model

Answer 26

No flipping, binding at one subunit causes change in the other subunits

Question 27

Kinase

Answer 27

Add phosphoryl

Question 28

Phosphatase

Answer 28

Remove phosphoryl

Question 29

Proteolytic cleavage

Answer 29

Enzyme exists as inactive precursor which is cleaved to become active