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Biochemistry 2 > Module 6 (ChatGPT) > Flashcards

Module 6 (ChatGPT) Flashcards

1
Q

What are enzymes?

A

Enzymes are proteins (or RNA molecules in some cases) that act as biocatalysts, increasing reaction rates by lowering activation energy.

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2
Q

What is the active site of an enzyme?

A

The active site is the part of the enzyme that binds specifically to its substrate, often described using the lock-and-key analogy.

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3
Q

What does the term ‘substrate’ refer to in enzymology?

A

A substrate is the molecule upon which an enzyme acts to catalyze a chemical reaction.

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4
Q

What happens during feedback inhibition?

A

In feedback inhibition, the end product of a pathway binds allosterically to an upstream enzyme, inhibiting its activity to regulate supply and demand.

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5
Q

What is the Michaelis-Menten equation?

A

V₀ = (Vmax [S]) / (Km + [S]), where V₀ is reaction velocity, Vmax is maximum velocity, [S] is substrate concentration, and Km is the Michaelis constant.

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6
Q

What is the relationship between substrate concentration and reaction velocity?

A

The relationship is hyperbolic; as substrate concentration increases, reaction velocity approaches but never reaches Vmax.

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7
Q

What does the Michaelis constant (Km) indicate?

A

Km is the substrate concentration at which the reaction velocity is half of Vmax. It reflects the enzyme’s affinity for its substrate.

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8
Q

What is the significance of Vmax?

A

Vmax is the maximum velocity of an enzyme-catalyzed reaction when the enzyme is saturated with substrate.

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9
Q

What is the mechanism of action for Warfarin?

A

Warfarin inhibits glutamate carboxylase by competing with Vitamin K, reducing blood clot formation.

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10
Q

What is the role of calcium in the blood clotting cascade?

A

Calcium acts as a cofactor, stabilizing proteases via chelation, enabling proper enzyme folding and activity.

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11
Q

What does alcohol dehydrogenase (ADH) do?

A

ADH catalyzes the conversion of ethanol to acetaldehyde in the liver as part of alcohol metabolism.

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12
Q

How is trypsin activated?

A

Trypsinogen, the inactive precursor, is activated by proteolytic cleavage, an example of irreversible covalent regulation.

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13
Q

What is competitive inhibition?

A

Competitive inhibition occurs when an inhibitor binds to the active site of an enzyme, preventing substrate binding.

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14
Q

How does noncompetitive (mixed) inhibition work?

A

Noncompetitive inhibition occurs when an inhibitor binds to a site other than the active site, altering enzyme conformation.

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15
Q

What are biocatalysts?

A

Biocatalysts, such as enzymes, increase the reaction rate without being consumed in the reaction.

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16
Q

What is the lock-and-key analogy?

A

The lock-and-key analogy describes how the enzyme’s active site (lock) is specific to its substrate (key).

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17
Q

What is enzyme specificity?

A

Enzymes are specific, meaning they only catalyze reactions for specific substrates.

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18
Q

What happens to enzymes after the reaction?

A

Enzymes remain unchanged after the reaction and can catalyze additional reactions.

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19
Q

What factors affect enzyme activity?

A

Factors include pH, temperature, substrate concentration, and regulatory molecules.

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20
Q

How does pH affect enzyme activity?

A

Changes in pH can alter enzyme conformation and affect substrate binding or catalytic efficiency.

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21
Q

What is the role of temperature in enzyme activity?

A

Temperature impacts molecular movement; high temperatures may denature enzymes.

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22
Q

Why are conformation changes important in enzyme activity?

A

Conformation changes alter enzyme shape, affecting substrate binding and catalytic activity.

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23
Q

What does V0 represent in enzyme kinetics?

A

V0 is the initial velocity of an enzyme-catalyzed reaction, measured as the reaction starts.

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24
Q

Why does V0 approach Vmax as substrate concentration increases?

A

At high substrate concentrations, all enzyme active sites are saturated, preventing further increases in velocity.

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25
Q

What is the Lineweaver-Burke plot?

A

It is a double-reciprocal plot used to estimate Vmax and Km values experimentally.

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26
Q

What is allosteric regulation?

A

Allosteric regulation occurs when a molecule binds to an enzyme at a site other than the active site, altering its activity.

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27
Q

What is phosphorylation?

A

Phosphorylation involves adding a phosphate group to a molecule, often regulating enzyme activity.

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28
Q

What is the role of kinases in phosphorylation?

A

Kinases transfer phosphate groups from ATP to specific molecules, regulating their activity.

29
Q

What is the difference between reversible and irreversible regulation?

A

Reversible regulation can be undone (e.g., phosphorylation), while irreversible changes (e.g., proteolytic cleavage) are permanent.

30
Q

What is the blood clotting cascade?

A

A series of enzymatic reactions activating clotting factors, leading to fibrin formation for blood clotting.

31
Q

How does Warfarin impact the blood clotting cascade?

A

Warfarin inhibits Vitamin K-dependent carboxylation, reducing clotting factor activation and preventing clots.

32
Q

What are zymogens?

A

Zymogens are inactive enzyme precursors that require activation by cleavage (e.g., trypsinogen to trypsin).

33
Q

What is the significance of Vitamin K in blood clotting?

A

Vitamin K is a coenzyme for glutamate carboxylation, enabling calcium binding crucial for clotting.

34
Q

What is the function of chymotrypsin?

A

Chymotrypsin is a protease that breaks down proteins in the digestive system.

35
Q

What is the role of aldehyde dehydrogenase (ALDH)?

A

ALDH converts toxic acetaldehyde to acetate during alcohol metabolism.

36
Q

How does feedback inhibition work in metabolic pathways?

A

End products bind allosterically to upstream enzymes, reducing their activity to maintain balance.

37
Q

What is metabolism?

A

Metabolism is the sum of all biochemical reactions in a cell or organism, including catabolism and anabolism.

38
Q

What is catabolism?

A

Catabolism breaks down molecules into smaller units, releasing energy (e.g., glucose to pyruvate).

39
Q

What is anabolism?

A

Anabolism builds larger molecules from smaller ones, requiring energy (e.g., protein synthesis).

40
Q

What is the role of ATP in cellular processes?

A

ATP provides energy for various cellular processes, including muscle contraction and biosynthesis.

41
Q

What are the two phases of glycolysis?

A

The preparatory phase (investment of ATP) and payoff phase (generation of ATP and NADH).

42
Q

What is the net yield of glycolysis?

A

Glycolysis yields 2 ATP, 2 NADH, and 2 pyruvate molecules per glucose.

43
Q

What happens in the citric acid cycle?

A

Acetyl-CoA is oxidized, producing NADH, FADH2, ATP (or GTP), and CO2 as waste.

44
Q

What is the role of NADH and FADH2 in the electron transport chain?

A

NADH and FADH2 donate electrons to the chain, driving ATP synthesis via oxidative phosphorylation.

45
Q

What is chemiosmosis?

A

The movement of protons down their gradient through ATP synthase, driving ATP production.

46
Q

What is the proton-motive force?

A

The electrochemical gradient created by proton transfer across the mitochondrial membrane.

47
Q

How many ATP are produced per glucose in cellular respiration?

A

Approximately 30-32 ATP, depending on conditions and cell type.

48
Q

Why does fermentation occur?

A

Fermentation regenerates NAD+ under anaerobic conditions, allowing glycolysis to continue.

49
Q

What are the products of lactate fermentation?

A

Lactate and 2 ATP are produced from glucose under anaerobic conditions.

50
Q

What is the role of modulators in allosteric enzymes?

A

Modulators bind at regulatory sites, altering enzyme conformation and either activating or inhibiting the enzyme.

51
Q

What is covalent modification in enzyme regulation?

A

Covalent modification, such as phosphorylation, alters enzyme activity by adding or removing functional groups.

52
Q

What is the difference between uncompetitive and competitive inhibition?

A

Uncompetitive inhibitors bind only to the enzyme-substrate complex, while competitive inhibitors compete with the substrate for the active site.

53
Q

How is enzyme activity measured?

A

Enzyme activity is typically measured by the rate of product formation or substrate consumption over time.

54
Q

Why are zymogens important?

A

Zymogens prevent premature enzyme activation, which could damage tissues (e.g., trypsinogen in the pancreas).

55
Q

How do enzymes play a role in drug action?

A

Enzymes can be drug targets, such as protease inhibitors for HIV or blood thinners like Warfarin.

56
Q

What are examples of extracellular enzymes?

A

Digestive enzymes like amylase and proteases break down macromolecules for nutrient absorption.

57
Q

What is the importance of the preparatory phase of glycolysis?

A

The preparatory phase invests ATP to phosphorylate glucose, making it more reactive.

58
Q

What is oxidative decarboxylation?

A

A reaction where a molecule loses a carbon atom as CO2 while being oxidized, as seen in the citric acid cycle.

59
Q

How is energy stored during cellular respiration?

A

Energy is stored in the form of high-energy electron carriers (NADH, FADH2) and ATP.

60
Q

What is the role of the citric acid cycle in metabolism?

A

The citric acid cycle oxidizes acetyl-CoA, generating NADH, FADH2, and GTP/ATP for energy production.

61
Q

What is beta-oxidation?

A

Beta-oxidation is the process of breaking down fatty acids into acetyl-CoA, NADH, and FADH2 for energy.

62
Q

What is the role of lactate dehydrogenase in fermentation?

A

Lactate dehydrogenase converts pyruvate to lactate, regenerating NAD+ for glycolysis under anaerobic conditions.

63
Q

What is the chemiosmotic theory?

A

The chemiosmotic theory explains ATP synthesis as driven by a proton gradient across the mitochondrial membrane.

64
Q

What happens in the electron transport chain?

A

Electrons are transferred through a series of complexes, driving proton pumping and creating a gradient for ATP production.

65
Q

What are cofactors and coenzymes?

A

Cofactors are non-protein molecules required for enzyme activity, including metal ions and organic coenzymes like NAD+.

66
Q

What is the function of Vitamin B5?

A

Vitamin B5 is a component of coenzyme A, essential for acetyl-CoA formation in metabolism.

67
Q

How does magnesium affect enzymes?

A

Magnesium stabilizes ATP and is required by many enzymes, especially in glycolysis.

68
Q

What are isoenzymes?

A

Isoenzymes are enzyme variants that catalyze the same reaction but differ in structure or regulation.

69
Q

What is the significance of Gibbs free energy in bioenergetics?

A

Gibbs free energy determines the spontaneity of a reaction, with negative values indicating a spontaneous process.

Biochemistry 2 (15 decks)

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