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VP Cell Physiology > Test 2 Enzymes > Flashcards

Test 2 Enzymes Flashcards

1
Q

What are the (3) main processes that use enzymes?

A

Fermentations, biotransformations, and pharmaceutical industry.

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2
Q

What is an enzyme?

A

Protein catalyst that binds to other molecules and increases the rate of reactions by lowering activation energy without being changed themselves. Direct substrate molecules through a specific reaction pathway.

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3
Q

What are enzymes used for in medicine?

A

Treat diseases (lactose intolerance), generate drugs (penicillin), and diagnose diseases.

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4
Q

What is the Km value of an enzyme an indicator for?

A

Its affinity for the substrate.

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5
Q

How is reversible binding of enzymes possible?

A

Due to the 3-D structure of proteins generating sites for other molecules.

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6
Q

Enzymatic Binding Sites

A

Very specific for a particular ligand and binding is reversible.

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7
Q

How to tell if it is an enzyme?

A

All enzymes end in -ase.

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8
Q

What are the major classes of enzymes?

A
  1. Oxidorectuctases
  2. Transferases
  3. Hydrolases
  4. Lyases
  5. Isomerases
  6. Ligases
  7. Polymerases
  8. Proteases
  9. Kinases
  10. ATPases
  11. Synthases
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9
Q

What do oxidoreductases do?

A

Reactions where one molecules is oxidized while the other is reduced. (oxidases, reductases, dehyrdogenases)

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10
Q

What do transferases do?

A

Transfer carbon, nitrogen or phosphate groups.

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11
Q

What do hydrolases do?

A

Catalyze a hydrolytic cleavage reaction. (nucleases and proteases)

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12
Q

What do lyases do?

A

Catalyze the cleavage of C-C, C-S, and C-N bonds.

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13
Q

What do isomerases do?

A

Catalyze the arrangement of bonds within a single molecule.

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14
Q

What do ligases do?

A

Join together (ligate) two molecules in an energy dependent process.

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15
Q

What do polymerases do?

A

Catalyze polymerization reactions; synthesis of DNA and RNA.

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16
Q

What do proteases do?

A

Breakdown proteins by hydrolyzing bonds between amino acids.

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17
Q

What do kinases do?

A

Catalyze the addition of phosphate groups to molecules.

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18
Q

What to ATPases do?

A

Hydrolyze ATP.

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19
Q

What do synthases do?

A

Synthesize molecules in anabolic reactions by condensing two smaller molecules together.

20
Q

Enzyme Active Site

A

Special pocket for substrate binding. Binding causes a conformational change in the enzyme that allows catalysis to proceed.

21
Q

Properties of Enzymes

A
  1. Efficiency
  2. Specificity
  3. Sometimes they require cofactors to work.
  4. Can be regulated; increased and decreased.
  5. Located in specific organelles.
22
Q

Km Value

A

Discovered by Michaelis; the Michaelis Constant; AFFINITY of the enzyme of its substrate.

23
Q

What type of curve do allosteric enzymes show?

A

Sigmoidal Curve

24
Q

What type of curve do enzymes that follow the Michaelis-Menten kinetics show?

A

Hyperbolic Curve

25
Q

What do allosteric enzyme do?

A

They change the conformation of the binding site.

26
Q

How does substrate concentration affect the velocity of the reaction?

A

The rate of an enzyme reaction increases with substrate concentration until a maximal velocity (Vmax) is reached.

27
Q

How does temperature affect the velocity of a reaction?

A

Reaction velocity increases with temperature until a peak is reached. Too high temperature will lead to denaturation. OPTIMAL TEMP: 35-40C

28
Q

How does pH affect the velocity of a reaction?

A

Extreme pH (concentration of H+) will denature enzymes. Optimum pH of enzymes will vary.

29
Q

What is an enzyme inhibitor?

A

Any substance that can diminish the velocity of an enzyme-catalyzed reaction.

30
Q

What is a competitive inhibitor?

A

Bind to the same site that the substrate would occupy, reducing affinity. Increases Km, Vmax is unchanged.

31
Q

What is a noncompetitive inhibitor?

A

Binds at a different site from the substrate. Preventing the reaction from occurring. Decreases the Vmax. Do NOT interfere with the binding of the substrate to the enzyme.

32
Q

What are cofactors used for?

A

Small molecules used as a helper of the catalytic activity of many enzymes.

33
Q

What is a zymogen?

A

Inactive enzyme precursor. Example: trypsinogen, proinsulin and pepsinogen. Ends in -inogen or begins with pro-.

34
Q

What is the cofactor for the enzyme lactate dehydrogenase?

A

nicotinamide adenine dinucleotide.

35
Q

What is the cofactor for the enzyme Acetyl CoA carboxylase?

A

Coenzyme A (CoA).

36
Q

What are coenzymes?

A

Cofactors that are small organic molecules. Often derived from vitamins.

37
Q

Which coenzymes bind tightly?

A

Prosthetic groups. Example: heme group.

38
Q

What is the cofactor for hexokinase?

A

Mg2+

39
Q

What are mechanisms for regulating enzyme activity?

A

Gene expression (slow control but lasts longer) and enzyme activity.

40
Q

What does covalent modification do to enzyme activity?

A

Turn enzyme on or off by adding/removing phosphate groups from specific amino acids.

41
Q

What does allosteric regulation do to an enzyme?

A

Controls enzyme kinetics. Conformational change of an enzyme.

42
Q

What regulation mechanisms affect enzyme activity?

A

Covalent modification and allosteric regulation.

43
Q

How are allosteric enzymes regulated?

A

By effectors that bind at a site other than the active site altering the affinity of the enzyme for its substrate.

44
Q

What is a homotropic effector?

A

The substrate itself serves as the effector. Ex: hemoglobin.

45
Q

What is a heterotrophic effector?

A

Feedback inhibition.

46
Q

What does the induction or repression of enzyme synthesis do?

A

Regulates the amount of enzyme, altering the rate of enzyme degradation or the rate of synthesis.

VP Cell Physiology (5 decks)

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