C1.1 Enzymes

Question 1

Metabolism

Answer 1

A complex network of interdependent and enzyme catalyzed chemical reactions occuring in living organisms

Question 2

Anabolic reactions

Answer 2

Synthesis of polymers from smaller monomers

Question 2

Anabolic & catabolic acronym

Answer 2

Anabolic = assemble, catabolic = cut down

Question 3

Effect on active site in - Catabolic Reactions

Answer 3

Enzymes active site affects the bonds in the substrate so they are easier to break. to smaller molecules

Question 3

Enzymes

Answer 3

Biological catalysts which speed up the rate of a reaction without being used up themselves

Question 4

Enzyme Info

Answer 4

• reduce activation energy of a reaction
• can work intracellular and extracellular
• globular proteins
• tertiary structure

Question 5

Enzyme Mechanism

Answer 5

specificity = enzyme substrate complex = enzyme product complex = release of product

Question 6

Lock-and-key assumptions

Answer 6

assumes the active site of an enzyme is rigid in its shape

Question 6

Induced fit

Answer 6

suggests the active site is flexible and only assumes catalytic conformation after the substrate molecules bind to the site

Question 7

Enzyme immobilisation

Answer 7

Enzymes can be immobolised by being embeded in the membrane of cells

Question 7

Denaturation

Answer 7

An irrevsersible change to a proteins active site

Question 7

How enzymes operate in anabolic reactions

Answer 7

1. enzymes hold substrates close together
2. reduce repulsion
3. bonds more easily

Question 8

How enzymes operate in catabolic reactions

Answer 8

1. enzymes active site puts strain on bonds
2. fitting the substrate into active site puts strain on bonds
3. easier to break

Question 9

activation energy

Answer 9

energy needed to start a reaction

Question 10

How PH affects enzyme activity

Answer 10

• a change in pH from the optimum affects the charges of the enzyme proteins
• alters 3e structure
• denaturation
• goes up and rapidly down

Question 11

How substrate concentration affects enzymes rate of reaction

Answer 11

• increased substrate concentration leads to increased reaction rate as more ESC are formed
• until saturation point
• increases sub. conc. will not increase rate of reaction anymore as all enzymes active sites are occupied
• no more ESC
• plateaus

Question 12

Metabolic pathway

Answer 12

Any chain or cycle of linked reactions catalysed by enzymes

Question 13

competitive inhibitor mechanism

Answer 13

• similar shape to substrate
• binds to active site

Question 14

non competitive inhibitor mechanism

Answer 14

• binds to allosteric site
• substrate no longer fits

Question 15

Type of non competitive inhibition

End Product Inhibition

Answer 15

In order to control metabolic pathways the end product of the pathway can sometimes inhibit the activity of the first enzyme in the pathway

(avoids excessive prodcution & build up)

Question 16

competitive inhibitor

Answer 16

A mechanism in which the inhibitor competes with the substrate to bond with the actuve site

Question 17

non competitive inhibitor

Answer 17

A mechanism in which the inhibitor to an allosteric site away from the enzymes active site

Question 18

Metabolic rate

Answer 18

Amount of energy needed by that organism in a given time period

Question 19

mechanism (suicide) based inhibition

Answer 19

inhibitor binds permanently to the active site

ex: anti cancer, anti HIV, antibiotic

Question 20

Inactive precursors

Answer 20

types of enzyme that have an inhibitor on it, this it only works in certain coniditions

Question 21

# Inactive precursor Protease

Answer 21

* an inactive precursor * means that it only works under acidic PH conditions * to prevent protein degration

Question 22

Why when substrate conc. increase; rate increase?

Answer 22

More frequent collisions

Question 23

competitive inhibitor - descripitive graph

Answer 23

* slows down rate of reaction as it competes for active site * has a similar shape to substrate * binding is reversible * as substrate conc. increases; more binds to active site than competitor = reaction rate increases * plateaus as all active sites will be at full capacity

Question 24

catabolism

Answer 24

breaking down complex molecules into smaller monomers

Question 25

Importsnce of enzymes in metabolism

Answer 25

* lower activation energy * increase rate of reaction * end product inhibition can control metabolic pathways * specific enzyme for each substrate

Question 26

Outline Lock and Key model

Answer 26

* explains specificity of enzyme-substrate * the substrate (key) fits into enzymes active site (lock) * active site can only be changed through temperature & pH changes => substrate cannot bind

Question 27

Outline induced fit model

Answer 27

* as ESC is formed; active site changes to allow substrate to bind * substrate induces active site to change * bonds weakend in the substrate (easier to break) * easier to break bonds = lowers activation energy * opportunities for wider substrate specificity

Question 28

How do bacteria develop resistance to penicillin?

Answer 28

* modifying the structure of their transpeptidase enzymes * prevents the irreversible binding of penicillin to the active site.