ENZYMES Flashcards

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1
Q

What is meant by enzyme specificity? (1)

A

enzymes are highly specific in their reaction, catalyse only one reactions or a very small group of highly similar reactions ‘recognises’ substrate molecules.

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2
Q

what is a catalyst? (1)

A

a substance that increases the rate of a chemical reaction and is chemically unaffected by the reaction it catalyses.

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3
Q

what is the optimum temperature in enzymes for humans? (1)

A

37 degrees

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4
Q

what do enzymes do? (1)

A

lower the activation energy of a reaction.

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5
Q

what is meant by the activation energy? (1)

A

the energy barrier that must be overcome before reactants reach their temporary transition state.

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6
Q

what are the disadvantages of the lock and key model? (1)

A

studies show it is too simplistic (enzyme molecule does change shape)

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7
Q

what happens when molecules react? (1)

A

they become unstable intermediates but only momentarily whilst they come to their transition state.

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8
Q

what factors effect the rate of the reaction of enzymes? (4)

A

-temperature
-pH
-substrate concentration
-enzyme concentration

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9
Q

what is needed for a reaction to occur? (2)

A

-there must be successful collisions between two molecules
-must collide at the right angle and the right velocity

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10
Q

what is the lock and key model? (1)

A

the enzyme and substrate molecules have a fixed shape and the substrate fits into the active site of the enzyme (like a lock and key)

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11
Q

what is an example of a catabolic reaction? (2)

A

-digestion of complex foods
-break down of sugars in respiration

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12
Q

what are the properties of enzymes? (3)

A

-do not change the nature of the reaction they catalyse
-are effective in small concentrations
-remain chemically unchanged at the end of a reaction

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13
Q

what are anabolic reactions? (1)

A

in anabolic reactions, larger molecules are built up from smaller molecules.

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14
Q

what are the conditions for chemical reactions in the human body? (4)

A

-normal temperature
-neutral aqueous conditions
-low concentrations of reactants

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15
Q

what is an example of a anabolic reaction? (2)

A

-synthesis of proteins from amino acids
-synthesis of polysaccharides from simple sugars

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16
Q

what is a metabolite? (1)

A

used to describe any molecule involved in the reactions occurring in cells and organisms (involved in the metabolism)

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17
Q

what are catabolic reactions? (1)

A

in catabolic reactions, larger molecules are broken down.

18
Q

how can industry induce a chemical reaction? (5)

A

-application of high temperatures
-applications of high pressures
-extreme pHs
-high concentrations of reacting molecules
-catalysts

19
Q

what are the two types of metabolic reactions? (2)

A

-anabolic reactions
-catabolic reactions

20
Q

what are enzymes known as? (1)

A

biological catalysts

21
Q

what is a limiting factor? (1)

A

any factor that limits the rate which a reaction or process can occur.

22
Q

what are non-competitive inhibitors? (1)

A

bind to the enzyme at a site other than the active site and by doing so cause the shape of the enzymes active sit to change.

23
Q

what have studies of enzyme inhabitation helped understanding of? (3)

A

-chemistry of the active site
-natural regulation of metabolism
-ways in which certain commercial pesticides and drugs work.

24
Q

is the effect of pH reversible? (1)

A

usually reversible.

25
Q

what are the two phases to an enzyme concentration curve? (2)

A

-lower enzyme concentration - rate increases in direct proportion to the increase in concentration.
-higher enzyme concentration - rate becomes constant, showing increase in enzyme concentration.

26
Q

what is an enzyme inhibitor? (1)

A

a substance that slows the rate of an enzyme controlled reaction by preventing binding of a substrate to the active site of an enzyme.

27
Q

what is the optimum pH? (1)

A

the value or narrow range of values over which an enzyme-catalysed reaction is fastest.

28
Q

is the effect of temperature reversible? (1)

A

no, its permeant change

29
Q

what is a substrate? (1)

A

a molecule that binds to the active site of an enzyme to form an enzyme-substrate complex, it is then converted to a product.

30
Q

what is an enzyme? (1)

A

an organic catalyst that speeds up a metabolic reaction in cells and organisms

31
Q

what are competitive inhibitors? (1)

A

bind directly to the enzyme active site, blocking access to the substrate.

32
Q

what are the types of enzyme inhibitors? (2)

A

-competitive
-non-competitive

33
Q

how does temperature effect a biological reaction? (3)

A

-the random thermal movement of particles cause the rate to increase
-the rate of denaturation of protein molecules which happens because high temperatures cause such violent movements of particles within a protein molecule that the bonds holding the protein molecule together break so its active site looses shape.

34
Q

what is meant by random thermal movement? (1)

A

the movement shown by all particles at temperatures above absolute 0. as the temperature increases so does the rate of random thermal movement.

35
Q

how do enzymes work? (2)

A

binds to a specific substance known as its substrate molecule at a specifically formed pocket in the enzyme called its active site. as they bind they form an unstable enzyme complex which immediately breaks down to form products.

36
Q

what are the two phases to a substrate concentration curve? (2)

A

-lower concentration - the rate increases in direct proportion to increases in substrate
-higher concentration - the rate of reaction becomes constant, no further increase.

37
Q

what is the induced fit hypothesis? (1)

A

a model used to explain enzyme reaction.
when an enzyme and substrate combine, the enzyme active site changes shape to become truly complementary to the part of the substrate to which it attaches.

38
Q

what is optimum temperature? (1)

A

the temperature at which the rate of an enzyme controlled reaction is fastest (there is a balance between an increase in successful collisions between E and S and loss of active enzyme molecules as a result of denaturation)

39
Q

how does pH effect a biological reaction? (1)

A

the structure of a protein (shape of active site) is maintained by various bonds within the 3D structure of a protein. a change in pH alters bonding patterns therefore the active site is progressively changed.

40
Q

what is active site? (1)

A

enzyme molecules usually much bigger than their substrate molecules. the active site is small part of the enzyme molecule that binds to its specific substrate and causes the catalysis.