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A level Biology- KE > Module 2- Enzymes > Flashcards

Module 2- Enzymes Flashcards

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1
Q

what is the role of an enzyme?

A

-biological catalysts
-increases rate of reaction by reducing Ea
-remains unchanged and reusable at the end of the reaction

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2
Q

what is an anabolic reaction?

A

requires energy, building up of simple molecules to form new molecules, required for growth

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3
Q

what is the lock and key hypothesis?

A

substrate has a spepecific+complementry shape to the active site

active site does not change shape to fit the substrate.

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4
Q

what is the induced fit hypothesis?

A

states active site is flexible and changes shape to mold around substrate as it binds-closer fit

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5
Q

how does the ESC increase rate of reaction?

A

initial interaction of enzyme + substrate is quite weak,,,weak interactions rapidly induce changes in tertiary structure of enzyme strengthening binding in ESC + strains substrate molecule,,, weakens bonding in substrate therefore lowering Ea

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6
Q

what is meant by specificity of an enzyme?

A

each enzyme catalyses 1 biochemical reaction

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7
Q

what enzyme catalyses hydrogen peroxide and is it intracellular or extracellular/

A

catalase- broken down into non toxic O and H2O before H2O2 can accumulate

intracellular

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8
Q

what is an intracellular enzyme?

A

acts within cells e.g. catalase

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9
Q

what is an extracellular enzyme?

A

secreted by cells and catalyse reactions outside cells

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10
Q

what enzyme catalyses starch and is it intracellular or extracellular?

A

amylase- catalyses starch into maltose

extracellular

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11
Q

what enzyme catalyses maltose?

A

maltase- catalyses maltose into glucose

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12
Q

why are different enzymes needed for digestion?

A

each enzyme only catalyses one specific reaction

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13
Q

what is trypsin?

A

a protease (enzyme that catalyses digestion of proteins into smaller peptides then amino acids by other proteases)

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14
Q

how does competitive inhibition work?

A

-inhibitor + substrate have complimentary shape to active site
-blocks substrate from entering active site + catalysing reaction
-enzyme is inhibited (cannot carry out function)

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15
Q

how do competitive inhibitors slow down rate of reaction?

A

-substrate + inhibitors in solution compete with each other to bind to active sites of enzymes catalysing reaction
-reduces amount of ESC formed in given time ∴ slowing down rate of reaction

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16
Q

what does the degree of competitive inhibition depend on?

A

relative concentration of inhibitor, substrate, enzyme

17
Q

are all competitive inhibitors permanent?

A

most are temporary ∴ effect is reversible. exceptions include aspirin.

18
Q

examples of competitive inhibition?

A

statins- competitive inhibitors of enzymes used in synthesis of cholesterol in the liver (helps reduce blood cholesterol concentration)

aspirin- irreversibly inhibits COX enzyme preventing synthesis of prostaglandins thromboxane (pain+fever causing chemicals)

19
Q

what effect do competitive inhibitors have on rate of reaction?

A

reduces but does not change the maximum rate of reaction the enzyme inhibits

20
Q

how does non-competitive inhibition work?

A

-inhibitor binds to enzyme at allosteric site
-binding of inhibitor causes tertiary structure of enzyme to change shape, including active site
-active site no longer complementary to substrate
-enzyme cannot carry out function because substrate cannot bind
-enzyme is inhibited

21
Q

what is the allosteric site?

A

alternative site on enzyme to active site

22
Q

what effect does non-competitive inhibition have on rate of reaction?

A

-increasing concentration slows rate of reaction as less active sites become available,, fewer ESC

23
Q

examples of non-competitive inhibitors?

A

Proton pump inhibitors (PPIs)- used to treat long term indigestion,,,irreversibly blocks enzyme system responsible for secretion of H+ in stomach ∴ recuses production of excess acid which leads to stomach ulcers

24
Q

what is end-product inhibition?

A

enzyme inhibition which occurs when end product of reaction acts as an inhibitor for enzyme that produced it– non-competitive reversible inhibition

25
Q

what is the effect of low pH on enzyme activity?

A

-Hydrogen ions attract the negative r-groups in hydrogen and ionic bonds which causes them to break
-this changes the tertiary structure of the enzyme ∴ the active site is no longer complimentary to the substrate ∴ fewer ESC are formed ∴ decreasing rate of reaction

26
Q

what is the effect of high pH on enzyme activity?

A

same of low pH except hydroxide ions attract positive r-groups in hydrogen and ionic bonds

27
Q

what is the effect of high temperature on enzyme activity?

A

the enzyme and substrate gain KE ∴ there are more successful collisions between substrate and active site ∴ more ESC

28
Q

what is the effect of high temperature after the optimum temperature?

A

-after optimum temperature due to gaining lots of KE the enzymes vibrate more causing strain on the bonds in tertiary structure of the enzyme and breaking these bonds∴ the active site is no longer specific to the substrate ∴ less ESC formed
-causes irreversible damage to active site
-enzyme becomes denatured

29
Q

how does increased substrate concentration effect rate of reaction?

A

more successful collisions between enzyme and substrate ∴ more ESC are formed until all active sites have become saturated so enzyme concentration becomes limiting factor

30
Q

how does enzyme concentration effect rate of reaction?

A

more successful collisions between enzyme and substrate ∴ more ESC are formed until all substrate is used up so substrate concentration becomes limiting factor

31
Q

what is the temperature coefficient?

A

Q₁₀=R₂/R₁

32
Q

whats the difference between a cofactor and a coenzyme?

A

cofactors are inorganic molecules whereas coenzymes are organic molecules

33
Q

what is the chloride ion (Cl-) a cofactor for and what does it do?

A

amylase,, forms a correctly shaped active site

34
Q

what are many coenzymes derived from?

A

vitamins via someones diet as they are organic molecules

35
Q

what is a cofactor/coenzyme?

A

non-protein components necessary for the effective functioning of an enzyme,, bound loosely to the protein

36
Q

what is the role of prosthetic groups in enzymes?

A

tightly bound to the protein to form a permanent feature on the protein

37
Q

what is the prosthetic group for carbonic
anhydrase?

A

Zn2+

38
Q

how can you measure the rate of reaction using hydrogen peroxide and catalase?

A

measure the volume of oxygen gas produced in a given time

39
Q

what are the hazards in the hydrogen peroxide catalase practical?

A

-hydrogen peroxide is an irritant,, wear eye protection + avoid contact with skin
-take care in handling hot water baths

A level Biology- KE (20 decks)

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