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01 Cell > 2.09 Enzymes > Flashcards

2.09 Enzymes Flashcards

1
Q

specialized protein catalysts that accelerate chemical reactions, used in biochemical reactions and pathways

A

Enzymes

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2
Q

Mechanism of enzymes wherein there is conformational change when the substrate binds to the enzyme’s active site

A

Induced fit (Daniel Koshland)

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3
Q

The molecule acted upon by the enzyme to form a product

A

Substrate

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4
Q

Enzymes that require a metal in their composition

A

Metalloenzymes

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5
Q

Parts of a holoenzyme

A

Protein part

Cofactor (Non-protein part)

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6
Q

Examples of Cofactors

A

Coenzymes
Prosthetic groups
Metal Ions

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7
Q

Classes of Coenzymes

A

Activation Transfer Coenzymes

Oxidation Reduction Coenzymes

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8
Q

What to look for in enzyme cofactors

A

Coenzyme
Enzyme
Chemical groups transferred
Vitamin Precursor

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9
Q

The enzyme that catalyzes the rate-limiting or committed step of a metabolic pathway

A

Regulatory enzyme

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10
Q

Intracellular locations of some important biochemical pathways

A

Mitochondria
Cytosol
Nucleus
Lysosome

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11
Q

Different structural forms of an enzyme which catalyze the same chemical reactions

A

Isoenzyme

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12
Q

Enzymes that act on the same substrate and produce the same products but exhibit differing degrees of efficiency

A

Isoenzyme

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13
Q

Six major classes of enzymes

A 
Oxidoreductases
Transferases
Hydrolases
Lyases
Lysases
Isomerases
Ligases
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14
Q

Part of the enzyme which contains amino acid side chains that participate in substrate binding and catalysis

A

Active site

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15
Q

Enzyme that transfer of electron and hydrogen atoms from donors

A

Oxidoreductases

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16
Q

Enzyme that transfers functional groups from donors to acceptors

A

Transferases

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17
Q

Enzyme that csatalyze cleavage of chemical bonds by addition of H2O, producing 2 products

A

Hydrolases

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18
Q

Enzyme that cleaves C-C, C-O, and C-N bonds by means other than hydrolysis or oxidation

A

Lyases

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19
Q

Enzyme that catalyzes a psychologically important reaction that favors the formation of a C-C bond

A

Synthase

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20
Q

Type of lyases that adds H2O to a substrate

A

Hydratase

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21
Q

Transfer of functional groups or double bonds within the same molecule

A

Isomerases

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22
Q

Enzyme that catalyzes the joining of substrates in the presence of ATP

A

Ligases

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23
Q

Characteristics of enzymes

A

Not changed in the reaction
Do not change or alter the equilibrium of the reaction
Increase reaction rates by decreasing activation energy
Highly specific
Mostly proteins in nature

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24
Q

Significance of the Km

A

1) Substrate concentration at which half the active sites of the enzyme are filled up
2) Inverse measure of the affinity of the substrate for the enzyme

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25
Q

Reversible inhibitions of enzymatic reactions

A

Competitive
Non competitive
Uncompetitive

26
Q

Type of inhibition wherein the inhibitor binds specifically at the active or catalytic site, where it competes with the substrate for binding

A

Competitive inhibition

27
Q

Type of inhibition wherein the inhibitor binds a substance other than at the active or catalytic site

A

Non competitive

28
Q

Type of inhibition wherein the inhibitor binds only to ES complexes at locations other than the catalytic site, modifying enzyme structure, making the inhibitor binding site available

A

Uncompetitive inhibition

29
Q

Type of inhibition wherein the inhibition is reversed by increasing substrate concentration

A

Competitive inhibition

30
Q

Type of inhibitor
Vmx: decrease proportionately to inhibitor concentration
Km: unchange

A

Non competitive inhibitor

31
Q

Type of inhibitor
Vmax: decrease
Km: decrease

A

Uncompetitive inhibitor

32
Q

Type of inhibitor
Vmax: unchange
Km: increase

A

Competitive inhibitor

33
Q

Enzymes following Michaelis-Menten kinetics show (linear/hyperbolic/sigmoid) curve.

A

Hyperbolic

34
Q

Allosteric enzymes exhibit (linear/hyperbolic/sigmoid) curve

A

Sigmoid

35
Q

Methods of regulating enzyme activity

A 
Feedback inhibition
Allosteric (non-covalent) modification
Covalent modification
Zymogen activation
Induction or repression of enzyme synthesis
36
Q

Binding of modulator to allosteric site, which causes a conformational change in the regulatory enzyme, alters the activity of the enzyme

A

Allosteric modification

37
Q

(Low/High) Activity

Dephosphorylating Acetyl Coa Carboxylase

A

High

38
Q

(Low/High) Activity

Phosphorylating Glycogen synthase

A

Low

39
Q

(Low/High) Activity

Phosphorylating Pyruvate dehydrogenase

A

Low

40
Q

(Low/High) Activity

Dephosphorylating HMG CoA reductase

A

High

41
Q

(Low/High) Activity

Phosphorylating Glycogen phosphorylase

A

High

42
Q

(Low/High) Activity

Dephosphorylating Citrate lyase

A

Low

43
Q

(Low/High) Activity

Dephosphorylating Phosphorylase b kinase

A

Low

44
Q

(Low/High) Activity

Phosphorylating HMG CoA reductase kinase

A

High

45
Q

(Low/High) Activity

Dephosphorylating HMG CoA reductase kinase

A

Low

46
Q

(Low/High) Activity

Phosphorylating Phosphorylase b kinase

A

High

47
Q

(Low/High) Activity

Phosphorylating Citrate lyase

A

High

48
Q

(Low/High) Activity

Dephosphorylating glycogen phosphorylase

A

Low

49
Q

(Low/High) Activity

Phosphorylasing HMG CoA reductase

A

Low

50
Q

(Low/High) Activity

Dephosphorylating pyruvate dehydrogenase

A

High

51
Q

(Low/High) Activity

Dephosphorylating glycogen synthase

A

High

52
Q

(Low/High) Activity

Phosphorylating Acetyl CoA carboxylase

A

Low

53
Q

Factors affecting enzyme activity

A

Temperature
pH
Substrate concentration
Co-factors

54
Q

As the temperature increases (until the optimum temperature is reached), the reaction velocity or the enzyme activity (increases/decreases)

A

Increases

55
Q

Beyond the optimum temperature, the reaction velocity/enzyme activity (increases/decreases) as the temperature increases

A

Decreases

56
Q

Increasing the pH value will (increase/decrease) the reaction rate

A

Increase

But, beyond the optimum pH, the reaction rate will decrease

57
Q

Cofactors (chlorides, bromides, iodides) ___ the rate of enzyme-catalyzed reactions

A

Increase

58
Q

As the substrate concentration increases, the reaction velocity (increases/decreases)

A

Increases

Up to a certain point

59
Q

Substate concentration at which half of the active sites of the enzyme are filled up

A

Km

60
Q

The lower the Km, the ___ is the affinity

A

Higher

61
Q

The higher the Km, the ___ is the affinity

A

Lower

62
Q

Models of enzyme-substrate complex

A

Lock and Key Model

Induced Fit Model

01 Cell (22 decks)

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