enzymes

Question 1

what do enzymes do?

Answer 1

biological catalysts that speed up chemical reactions without being used up during the reaction

Question 2

what is the structure of enzymes?

Answer 2

3D globular proteins with specific tertiary structure
active site that is complementary to the specific substrate

Question 3

what happens when the substrate binds with the active site?

Answer 3

an enzyme-substrate complex is formed

Question 4

what does the induced fit model show?

Answer 4

substrate collides with active site
active site molds around substrate molecule
enzyme-substrate complex formed
change in enzymes 3D shape places a strain on substrate which weakens chemical bonds
enzyme-product complex formed
products no longer fit so are released

Question 5

what is lysozyme?

Answer 5

enzyme found in tears and egg white
antibacterial
breaks down polysaccharides in bacterial cell walls

Question 6

what does lysozyme do?

Answer 6

catalyses hydrolysis of glycosidic bonds
breaks chains of beta glucoses

Question 7

what are catabolic reactions?

Answer 7

involve break down of larger molecules into smaller molecules (hydrolysis)

Question 8

what are anabolic reactions?

Answer 8

involve larger molecules being made from smaller molecules (condensation)

Question 9

where are enzymes made?

Answer 9

in cells by protein synthesis

Question 10

what are intracellular enzymes?

Answer 10

enzymes which remain inside the cell

Question 11

what are extracellular enzymes?

Answer 11

enzymes which are secreted from cells to function

Question 12

what is the turnover number?

Answer 12

maximum number of substrate molecules an enzyme can convert to product molecules per unit of time

Question 13

how does temperature affect enzyme activity FIRST PART OF GRAPH?

Answer 13

increases kinetic energy
more successful collisions
optimum temperature

Question 14

how does temperature affect enzyme activity SECOND PART OF GRAPH?

Answer 14

vibrations in molecules breaks hydrogen bonds
active site changed
enzyme has become denatured

Question 15

how does varying pH affect enzyme activity FIRST AND LAST PART OF GRAPH?

Answer 15

activity declines as pH moves away from optimum
hydrogen and ionic bonds broken
distorts enzyme shape

Question 16

how does the varying pH affect enzyme activity MIDDLE PART OF GRAPH?

Answer 16

optimum pH
charges on active site and substrate are complementary so attract

Question 17

how does the substrate concentration affect enzyme activity FIRST PART OF GRAPH?

Answer 17

activity increases as concentration increases
more successful collisions
more enzyme-substrate complexes being formed

Question 18

how does the substrate concentration affect enzyme activity SECOND PART OF GRAPH?

Answer 18

activity plateaus/levels off
enzyme is working at maximum rate

Question 19

how does enzyme concentration affect enzyme activity?

Answer 19

increases rate as more active sites
more successful collisions
more enzyme-substrate complexes formed

Question 20

how are enzymes made (industrial enzymes produced)?

Answer 20

culturing microbes in fermentation
microbes are removed
enzymes are extracted from culture and purified

Question 21

what is the source for protease?

Answer 21

bacillus

Question 22

what is the source for glucose isomerase?

Answer 22

fungus streptohycin

Question 23

what is the source for rennin?

Answer 23

fungus mucor

Question 24

what is the source for pectinase?

Answer 24

fungus aspergillus

Question 25

why are enzymes used in larger scale industrial production?

Answer 25

speed up rate of reaction lower activation energy so reaction can happen at lower temps to save money

Question 26

how are enzymes used in industrial processes?

Answer 26

substrates trickled through top of vessel reaction occurs as substrate passes over immobilised enzymes product collects at the bottom

Question 27

what are immobilised enzymes?

Answer 27

enzymes fixed/bound to an inert matrix such as alginate beads, cellulose, clay

Question 28

what are the advantages of immobilised enzymes?

Answer 28

can be used multiple times (continuous processes) product is not contaminated by enzyme enzyme is more stable at high temps and pHs several enzymes can be used at the same time

Question 28

why do we use immobilised enzymes?

Answer 28

so we can reuse the same enzymes over and over again

Question 29

what are the disadvantages of immobilised enzymes?

Answer 29

can become detached and contaminate product alginate gel changes active site shape complex and expensive to bond enzyme contamination is costly if it happens

Question 30

what are competitive inhibitors?

Answer 30

they have a similar shape to substrate molecules

Question 31

what do competitive inhibitors do?

Answer 31

bind to active site form an enzyme-inhibitor complex prevents substrate by blocking active site reduces number of enzyme-substrate complexes reduces rate of reaction

Question 32

what do non-competitive inhibitors do?

Answer 32

attach away from active site distort tertiary shape of enzyme changes active site substrate no longer fits enzyme-substrate complexes cannot form

Question 33

what does the graph for a non-competitive inhibitor look like?

Answer 33

reduced rate and would never reach the maximum rate of reaction

Question 34

how can inhibitors be reversible and non-reversible?

Answer 34

either permanently bind to active site or don't