PPT Enzyme: Regulation Of Activity - Dr. Bonleon

Question 1

Cannot respond to an increase in substrate concentration

Answer 1

Maximal rate

Question 2

Average intracellular concentration of their substrates tends to be close to the __________.

Answer 2

Km value

Question 3

Changes in substrate concentration generate corresponding changes in ___________.

Answer 3

Metabolic flux

Question 4

Coordinating metabolite flow and maintaining homeostasis in quiescent cells

Answer 4

Passive

Question 5

Limited scope for responding to changes in environmental variables

Answer 5

Passive

Question 6

Responses to changes

Answer 6

Passive

Question 7

Mean concentrations of metabolic intermediates remain relatively constant over time

Answer 7

Dynamic steady state

Question 8

With overall change in free energy that favors UNIDRECTIONAL metabolite flow

Answer 8

Coupled metabolic reactions

Question 9

Pathway with a large overall negative charge in free energy

Answer 9

Unidirectional flow

Question 10

Bends or kink (enzyme cat steps)

Answer 10

Unidirectional flow

Question 11

Ability to maintain a constant intracellular environment despite changes in the external environment

Answer 11

Homeostasis

*Organisms respond to changes (external and internal)

Question 12

Balanced, coordinated changes in the rates of specific metabolic reactions

Answer 12

Homeostasis

Question 13

Ensures metabolic efficiency

Answer 13

Compartmentation

Question 14

Simplifies regulation

Answer 14

Compartmentation

Question 15

Anabolic and catabolic pathways that interconvert common products may take place in specific subcellular compartments

Answer 15

Compartmentation

Question 16

Segregation of metabolic pathways

Answer 16

Compartmentation

Question 17

One or more unique intermediates can permit opposing pathways to coexist even in the absence of physical barrier

Answer 17

Physical compartmentation

Question 18

Enzymes discriminate between the structurally similar conezymes

Answer 18

Compartmentation

Question 19

Quantity or catalytic efficiency dictates that the reaction or catalysis is slow relative to all others in the pathway

Answer 19

Ideal enzyme

Question 20

Reduces metabolite flux through the entire pathway

Answer 20

Rate-limiting reaction

Question 21

Increase in either its quantity of catalytic efficiency enhances flux through the pathway as a whole

Answer 21

Ideal enzyme

Question 22

Catalyze the rate-limiting steps

Answer 22

Ideal enzyme

Question 23

Constitute efficient targets for regulatory intervention

Answer 23

Ideal enzyme

Question 24

Product of the concentration of enzyme molecules and their intrinsic catalytic efficiency.

Answer 24

Catalytic capacity of the rate-limiting reaction in a metabolic pathway

Question 25

Influenced by both changing the quantity of enzyme present and by altering its intrinsic catalytic efficiency

Answer 25

Catalytic capacity

Question 26

Enzymes whose concentrations remain constant over time.

Answer 26

Constitutive enzymes

Question 27

Substrates or structurally related compounds that initiate their syntheis and depended on by other enzymes

Answer 27

Inducers

Question 28

Way by which an excess of a metabolite may curtail synthesis of its cognate enzyme

Answer 28

Repression

Question 29

Absolute quantity of an enzyme reflects the net balance between enzyme synthesis and enzyme degradation

Answer 29

Enzyme degradation

Question 30

Net result of enzyme synthesis and degradation

Answer 30

Protein turnover

Question 31

Body is in a state of ______________

Answer 31

Dynamic equilibrium

Question 32

__________ and ___________ is a continuous process.

Answer 32

Synthesis and degradation

Question 33

Enzyme levels respond to:

Answer 33

1. Physiologic 2. Hormonal 3. Dietary

Question 34

Proteolytic degradation influenced by presence of ___________, substrates, coenzymes or metal ions that alter protein conformation.

Answer 34

Ligands

Question 35

Changes in ______ can alter ionization state of the substrate or the enzyme-binding site for substrate.

Answer 35

pH

Question 36

Changes in _______ can alter ionization state at the catalytic site on the enzyme

Answer 36

pH

Question 37

Changes in pH can alter _________ so that their conformation and catalytic activity change

Answer 37

Protein molecules

Question 38

Rate of an enzyme-catalyzed reaction __________ in temperature up to an optimum point then it _______ because enzymes are THERMOLABILE.

Answer 38

Increase | Decrease

Question 39

If the product accumulates, it can inhibit some enzymes.

Answer 39

Product inhibition

Question 40

Limits the rate of formation of the product when the product is underused.

Answer 40

Product inhibition

Question 41

Inhibition of an enzyme in a biosynthetic pathway by end products of that pathway not by “backing-up” of intermediates but from the ability of the end product to bind to and inhibit the enzyme.

Answer 41

Feedback inhibition

Question 42

Intrinsic catalytic efficiency effected by binding of dissociable ligands.

Answer 42

Allosteric regulation

Question 43

Serve long-term adaptive requirements

Answer 43

Changes in protein level

Question 44

For rapid and transient alterations in metabolite flux

Answer 44

Changes in catalytic efficiency

Question 45

Key regulatory enzymes (committed steps) subjected

Answer 45

Allosteric regulation

Question 46

Activity modulated by binding of allosteric effectors to a site on the enzyme distinct from the active site

Answer 46

Allosteric regulation

Question 47

Negative modulation of the committed step of a metabolic pathway by its end product.

Answer 47

Feedback inhibition

Question 48

Prevents unnecessary production of an excess of end product by shutting down the pathway until more is needed

Answer 48

Feedback inhibition

Question 49

End product binds at an ___________.

Answer 49

Allosteric site *Distinct from the catalytic site of the target enzyme

Question 50

If they enhance the rate of a reaction

Answer 50

Positive

Question 51

Activators

Answer 51

Positive

Question 52

If they decrease the rate of reaction

Answer 52

Negative

Question 53

Inhibitors

Answer 53

Negative

Question 54

Bear little or no structural similarity to the substrates of the enzymes they inhibit

Answer 54

Allosteric effectors

Question 55

End product may acts as “______________”

Answer 55

Negative allosteric effector

Question 56

Small molecule building blocks of macromolecules

Answer 56

Allosteric effectors

Question 57

Typically inhibit the 1st committed step in a biosynthetic sequence

Answer 57

Allosteric effectors

Question 58

End product typically only partially inhibits catalytic activity

Answer 58

Cooperative feedback inhibition

Question 59

Effect of an excess of 2 or more end products may be strictly additive or greater than their individual effect

Answer 59

Cooperative feedback mechanism

Question 60

Effectors are not isosteric with a substrate

Answer 60

Allosteric regulation

Question 61

Lack of structural similarity between a feedback inhibitor and the substrate for the enzyme whose activity it regulates.

Answer 61

Allosteric regulation

Question 62

Occupy another space

Answer 62

Allosteric

Question 63

Physically distinct from the catalytic site

Answer 63

Allosteric regulation

Question 64

Those whose activity at the active site may be modulated by the presence of effectors an allosteric site

Answer 64

Allosteric enzymes

Question 65

Substrate saturation kinetics are competitive

Answer 65

K-series

Question 66

The Km is raised without an effect in Vmax

Answer 66

K-series

Question 67

Conformational change may weaken the bonds between substrate and substrate-binding residues

Answer 67

K-series

Question 68

Allosteric inhibitor lowers Vmax without affecting the Km

Answer 68

V-series

Question 69

Alterations in Km and Vmax result from conformational changes at the catalytic site induced by binding of the allosteric effector at the allosteric site

Answer 69

V-series

Question 70

Primary effect may be to alter the orientation or charge of catalytic residues, lowering vmax

Answer 70

V-series

Question 71

The addition of a phosphate group to a specific amino acid residue (Ser, Tyr, Thr) by specific protein kinases dramatically enhance or depress activity

Answer 71

Phosphorylation

Question 72

May be dephosphorylated by specific phosphatases and reversible

Answer 72

Phosphorylation

Question 73

Activities of some enzymes are regulated by the reversible addition of a nucleotide to a specific amino acid.

Answer 73

Nucleotidylation

Question 74

An adenylated enzyme may be deadenylated by a specific enzyme and reversible.

Answer 74

Nucleotidylation

Question 75

Some enzymes are synthesized as proenzymes or zymogens (inactive forms)

Answer 75

Proteolytic cleavage

Question 76

Activated by being cleaved at a specific site in their polypeptide chain by specific proteases

Answer 76

Proteolytic cleavage

Question 77

Digestive enzymes that hydrolyze proteins

Answer 77

Proteolytic cleavage

Question 78

Blood clotting mediated by proteolytic zymogen activities of several serum enzymes

Answer 78

Proteolytic cleavage

Question 79

Devoid of mechanistic implications

Answer 79

Feedback regulations

Question 80

Mechanism for regulation of enzyme activity

Answer 80

Feedback inhibition

Question 81

Virtually all reactions in the body are mediated by____________.

Answer 81

enzymes

Question 82

____________ are protein catalysts that increase the rate of reactions without being changed in the overall process.

Answer 82

Enzymes

Question 83

Enzymes selectively channel reactants (__________) into useful pathways.

Answer 83

substrates

Question 84

Enzymes are ___________ increase the velocity of a chemical reaction.

Answer 84

catalysts

Question 85

_____________ isolate the reaction substrate or product from other competing reactions m provide purposeful pathways.

Answer 85

Compartmentalization