ENZYMES

Question 1

What are enzymes

Answer 1

Biological catalysts
Globular proteins
Cause substrate molecules to interact at a faster rate

Question 2

What are metabolic reactions

Answer 2

All the chemical reactions that take place in a cell

Question 3

What is a catalyst

Answer 3

Substance that increases rate of reaction
Doesn’t take part in reaction
Can be reused

Question 4

What is the Turnover number

Answer 4

Number of substrate moecluels an enzyme can catalyse per second

Question 5

What is the Vmax

Answer 5

Enzymes can only increase rate up to a certain point

Max rate of enzyme catalysed reaction

Question 6

What is a catabolic enzyme

Answer 6

Break substances down into smaller products
Releasing energy
E.g. Glucose

Question 7

WHat is an anabolic enzyme

Answer 7

Build up reactants
Suing energy
E.g. Synthesis of large polymer base compounds

Question 8

What is a modifying enzyme

Answer 8

Change substrate slightly

E.g. Alpha to beta glucose

Question 9

What are intercellular enzymes

Answer 9

Enzyme action takes place inside cells
E..g synthesis of plumbers from monomers
E.g. Polysaccharides from glucose

Question 10

Extra cellar enzymes

Answer 10

Nutrients need to provide substrate to cells for produc making
Nutrients in the form of polymers often - too large - have to be broken down before entering the cell
Enzymes released from cell and work outside cell they were released from

Question 11

Examples of extra cellular enzymes

Answer 11

For fungi and bacteria
Trypsin
Amylase

Question 12

Trypsin - digestion of protein

Answer 12

Breaks down protein into smaller peptides
Then broke. Down into amino acids
Trypsin produced by Pancras, released within pacreatic juices into small intestine
Amino acids absorbed by cells lining digestive system

Question 13

Digestion of starch

Answer 13

Broken down into maltose using amylose
Amylose produced y salivary glands and pancreas
Maltose broken down in small intestine into glucose by Maltase
Glucose - absorbed by cells into blood stream

Question 14

What part of the enzyme determines the specificity

Answer 14

Active site

Tertiary structure

Question 15

What are the 2 hypothesises for enzyme action

Answer 15

Induced fit

Lock and key

Question 16

Explain the induced fit hypothesis

Answer 16

New
Enzyme shape changes slightly as substrate enters
Initial enzyme - substrate interaction is weak but these interactions induc changes in tertiary structure, strengthening binding putting strain on substrate moecluels - weakening bands

Question 17

Lock and key hypothesis

Answer 17

WHne the substrate is bond to active site, enzyme subs state complex is formed
Substrates react adn product formed( enzyme product complex)
Products released and enzyme unchanged
Substrate held by enzyme -atom groups close enough to react. R groups within the active site of the enzyme will also interact with TEH substrate, forming temporary bonds = put strain on bonds in substrate

Question 18

Temperature- how does it affect enzyme activity

Answer 18

INCREASING temperature increases kinetic energy of particles

More frequently collide

Too hot - bonds in protein vibrate and strain, break and change 3D shape and active site
Q10 no longer applies

Question 19

Q10

Answer 19

Temperature coefficient

Measure of how rate of relation increases with a 10 degree rise in temperature

Question 20

What are thermophiles and how are their enzymes different

Answer 20

Extreme temperatures

Enzymes are more stable, high number of h bonds and sulphur bridges in tertiary structure, more resistance to change

Question 21

How does ph affect enzyme activity

Answer 21

Change in h+ concentration
Hydrogen and ionic bonds between Amino acid r groups old protein in precise 3D shape, bonds result from interaction between Omar and charged r groups resent on amino acids forming primary structure
Hydrogen ions interact with polar positively charged r groups

Question 22

Renaturation

Answer 22

Ph

Returns from post optimum shape,

BUT IF CHANGED SIGNIFICATNLY - denatured

Question 23

How specifically does ph affect interactions

Answer 23

Changes degree of interaction and interaction of r groups with each other

MORE h+= less r groups are able to interact with each other, bonds in enzyme. Break , changes shape

Less h+- lots of bonds, changes shape

Question 24

Ph buffer

Answer 24

Resists change in ph, mopping up excess h+ ions

Question 25

How does substrate and enzyme concentration affect enzyme activity

Answer 25

Increased substrate particles = higher collision rate between susbryaet and active site, more enzyme substrate complexe formed

Question 26

What does a graph look like for increasing. Substrate or enzyme concentration wand the effect on reaction rate

Answer 26

Rate of reaction increases up to a certain point At this point, all active sites are occupied form substrate particles adn no more esc's can be formed until products are released from active site If enzyme conc is increased, substrate conc becomes limiting factor

Question 27

Why do we need inhibitors

Answer 27

ENSURES NOT WASTING RPDOUCTS So reaction don't happen too fast Leads to build up of excess products

Question 28

WHat is a competitive inhibitor

Answer 28

Molecule or part of molecule has similar shape to substrate fo enzyme ``` Ca to into active site Blocks substrate from entering TEMPOARILY binds ( few exceptions e.g. Aspirin) ```

Question 29

How do competitive inhibitors affect reaction rate

Answer 29

Susstrate and inhibitor moecluels present in solution will compete with each other to bind to active site THis reduces number of substrate molecules binding to active site in given time and reduces rate Vmax can still be reached ,when susbryaet concentration is increased, so much more substrate tan inhibitor

Question 30

How does aspirin work

Answer 30

Irreversibly inhibits active site of COX enzymes Competitive Prevents synthesis of thromboxane, responsible for producing pain and fever

Question 31

Non competitive inhibition

Answer 31

Inhibitor binds to the enzyme at a site other than the active site Allosteric The binding of the inhibitor causes the tertiary structure of the enzyme to change = active site changes shape Active site no longer complementary to substrate Enzyme can't carry out function and doesn't compete with inhibitor for active site Some irreversible and some not

Question 32

Vmax - non competitive inhibitors

Answer 32

after a certain point, increasing concentration of substrate has no effect Vmax can't be reached because substrate isn't competing with enzyme for active site

Question 33

Organosphates

Answer 33

Used as insecticides and herbicides Irreversibly inhibit the enzyme acetyl chlorinetease an enzyme necessary for nerve impulse transition, can lead to muscle cramps, paralysis and even death

Question 34

What is end product inhibition

Answer 34

Non competitive reversible inhibition Enzyme inhibition that occurs when the product of a reaction acts as an inhibitor to the enzyme Serves as negative feedback mechanism for the reaction , excess RPDOUCTS are not made and resources not wasted E.g. Respiration and PSK and glucose

Question 35

What is a COFACTOR

Answer 35

Non protein helper May transfer atoms or groups from one reaction to another or form part of active site of the enzyme Some cofactors change the charge distribution of the surface of the substrate// active site making temporary bonds in the ESC form more easily

Question 36

How are inorganic cofactors obtained

Answer 36

Via diet as minerals e,g, iron, calcium ad chlorine

Question 37

Coenzymes

Answer 37

``` Organic cofactors ( contain C) Binds temporarily to sub rate Chemically changed Derived from vitamins E.g. Vitamin b3 used to synthesise NAD, responsible for transfer of H atoms between moecluels involved in restoration ```

Question 38

Prosthetic group cofactors

Answer 38

Cofactors containing prosthetic group Permenantly bound E.g. Zn2+ , to form part of carbonic anhydrase ( enzyme for metabolism of co2)

Question 39

Precursors activation

Answer 39

Many enzymes produced in an inactive form = inactive pecurosor enzymes Particularly damaging enzymes Need to undergo a change in tertiary shape -atctive site

Question 40

What is an inactive precursor enzyme called before and after COFACTOR is added?

Answer 40

Apoenzyme After- halo enzyme

Question 41

COFACTOR example

Answer 41

Amylase contains cl- ions, necessary for correctly formed activ site

Question 42

What are zymogens and pro enzymes

Answer 42

Precursor enzymes activated by change in tertiary structure by another enzymes action or change in conditions such as ph or temperature