enzymes Flashcards

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1
Q

what do enzymes do?

A

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

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2
Q

what is the structure of enzymes?

A

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

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3
Q

what happens when the substrate binds with the active site?

A

an enzyme-substrate complex is formed

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4
Q

what does the induced fit model show?

A

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

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5
Q

what is lysozyme?

A

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

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6
Q

what does lysozyme do?

A

catalyses hydrolysis of glycosidic bonds
breaks chains of beta glucoses

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7
Q

what are catabolic reactions?

A

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

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8
Q

what are anabolic reactions?

A

involve larger molecules being made from smaller molecules (condensation)

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9
Q

where are enzymes made?

A

in cells by protein synthesis

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10
Q

what are intracellular enzymes?

A

enzymes which remain inside the cell

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11
Q

what are extracellular enzymes?

A

enzymes which are secreted from cells to function

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12
Q

what is the turnover number?

A

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

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13
Q

how does temperature affect enzyme activity FIRST PART OF GRAPH?

A

increases kinetic energy
more successful collisions
optimum temperature

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14
Q

how does temperature affect enzyme activity SECOND PART OF GRAPH?

A

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

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15
Q

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

A

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

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16
Q

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

A

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

17
Q

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

A

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

18
Q

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

A

activity plateaus/levels off
enzyme is working at maximum rate

19
Q

how does enzyme concentration affect enzyme activity?

A

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

20
Q

how are enzymes made (industrial enzymes produced)?

A

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

21
Q

what is the source for protease?

A

bacillus

22
Q

what is the source for glucose isomerase?

A

fungus streptohycin

23
Q

what is the source for rennin?

A

fungus mucor

24
Q

what is the source for pectinase?

A

fungus aspergillus

25
Q

why are enzymes used in larger scale industrial production?

A

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

26
Q

how are enzymes used in industrial processes?

A

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

27
Q

what are immobilised enzymes?

A

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

28
Q

what are the advantages of immobilised enzymes?

A

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

28
Q

why do we use immobilised enzymes?

A

so we can reuse the same enzymes over and over again

29
Q

what are the disadvantages of immobilised enzymes?

A

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

30
Q

what are competitive inhibitors?

A

they have a similar shape to substrate molecules

31
Q

what do competitive inhibitors do?

A

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

32
Q

what do non-competitive inhibitors do?

A

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

33
Q

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

A

reduced rate and would never reach the maximum rate of reaction

34
Q

how can inhibitors be reversible and non-reversible?

A

either permanently bind to active site or don’t