Module 6 (ChatGPT) Flashcards
What are enzymes?
Enzymes are proteins (or RNA molecules in some cases) that act as biocatalysts, increasing reaction rates by lowering activation energy.
What is the active site of an enzyme?
The active site is the part of the enzyme that binds specifically to its substrate, often described using the lock-and-key analogy.
What does the term ‘substrate’ refer to in enzymology?
A substrate is the molecule upon which an enzyme acts to catalyze a chemical reaction.
What happens during feedback inhibition?
In feedback inhibition, the end product of a pathway binds allosterically to an upstream enzyme, inhibiting its activity to regulate supply and demand.
What is the Michaelis-Menten equation?
V₀ = (Vmax [S]) / (Km + [S]), where V₀ is reaction velocity, Vmax is maximum velocity, [S] is substrate concentration, and Km is the Michaelis constant.
What is the relationship between substrate concentration and reaction velocity?
The relationship is hyperbolic; as substrate concentration increases, reaction velocity approaches but never reaches Vmax.
What does the Michaelis constant (Km) indicate?
Km is the substrate concentration at which the reaction velocity is half of Vmax. It reflects the enzyme’s affinity for its substrate.
What is the significance of Vmax?
Vmax is the maximum velocity of an enzyme-catalyzed reaction when the enzyme is saturated with substrate.
What is the mechanism of action for Warfarin?
Warfarin inhibits glutamate carboxylase by competing with Vitamin K, reducing blood clot formation.
What is the role of calcium in the blood clotting cascade?
Calcium acts as a cofactor, stabilizing proteases via chelation, enabling proper enzyme folding and activity.
What does alcohol dehydrogenase (ADH) do?
ADH catalyzes the conversion of ethanol to acetaldehyde in the liver as part of alcohol metabolism.
How is trypsin activated?
Trypsinogen, the inactive precursor, is activated by proteolytic cleavage, an example of irreversible covalent regulation.
What is competitive inhibition?
Competitive inhibition occurs when an inhibitor binds to the active site of an enzyme, preventing substrate binding.
How does noncompetitive (mixed) inhibition work?
Noncompetitive inhibition occurs when an inhibitor binds to a site other than the active site, altering enzyme conformation.
What are biocatalysts?
Biocatalysts, such as enzymes, increase the reaction rate without being consumed in the reaction.
What is the lock-and-key analogy?
The lock-and-key analogy describes how the enzyme’s active site (lock) is specific to its substrate (key).
What is enzyme specificity?
Enzymes are specific, meaning they only catalyze reactions for specific substrates.
What happens to enzymes after the reaction?
Enzymes remain unchanged after the reaction and can catalyze additional reactions.
What factors affect enzyme activity?
Factors include pH, temperature, substrate concentration, and regulatory molecules.
How does pH affect enzyme activity?
Changes in pH can alter enzyme conformation and affect substrate binding or catalytic efficiency.
What is the role of temperature in enzyme activity?
Temperature impacts molecular movement; high temperatures may denature enzymes.
Why are conformation changes important in enzyme activity?
Conformation changes alter enzyme shape, affecting substrate binding and catalytic activity.
What does V0 represent in enzyme kinetics?
V0 is the initial velocity of an enzyme-catalyzed reaction, measured as the reaction starts.
Why does V0 approach Vmax as substrate concentration increases?
At high substrate concentrations, all enzyme active sites are saturated, preventing further increases in velocity.
What is the Lineweaver-Burke plot?
It is a double-reciprocal plot used to estimate Vmax and Km values experimentally.
What is allosteric regulation?
Allosteric regulation occurs when a molecule binds to an enzyme at a site other than the active site, altering its activity.
What is phosphorylation?
Phosphorylation involves adding a phosphate group to a molecule, often regulating enzyme activity.
What is the role of kinases in phosphorylation?
Kinases transfer phosphate groups from ATP to specific molecules, regulating their activity.
What is the difference between reversible and irreversible regulation?
Reversible regulation can be undone (e.g., phosphorylation), while irreversible changes (e.g., proteolytic cleavage) are permanent.
What is the blood clotting cascade?
A series of enzymatic reactions activating clotting factors, leading to fibrin formation for blood clotting.
How does Warfarin impact the blood clotting cascade?
Warfarin inhibits Vitamin K-dependent carboxylation, reducing clotting factor activation and preventing clots.
What are zymogens?
Zymogens are inactive enzyme precursors that require activation by cleavage (e.g., trypsinogen to trypsin).
What is the significance of Vitamin K in blood clotting?
Vitamin K is a coenzyme for glutamate carboxylation, enabling calcium binding crucial for clotting.
What is the function of chymotrypsin?
Chymotrypsin is a protease that breaks down proteins in the digestive system.
What is the role of aldehyde dehydrogenase (ALDH)?
ALDH converts toxic acetaldehyde to acetate during alcohol metabolism.
How does feedback inhibition work in metabolic pathways?
End products bind allosterically to upstream enzymes, reducing their activity to maintain balance.
What is metabolism?
Metabolism is the sum of all biochemical reactions in a cell or organism, including catabolism and anabolism.
What is catabolism?
Catabolism breaks down molecules into smaller units, releasing energy (e.g., glucose to pyruvate).
What is anabolism?
Anabolism builds larger molecules from smaller ones, requiring energy (e.g., protein synthesis).
What is the role of ATP in cellular processes?
ATP provides energy for various cellular processes, including muscle contraction and biosynthesis.
What are the two phases of glycolysis?
The preparatory phase (investment of ATP) and payoff phase (generation of ATP and NADH).
What is the net yield of glycolysis?
Glycolysis yields 2 ATP, 2 NADH, and 2 pyruvate molecules per glucose.
What happens in the citric acid cycle?
Acetyl-CoA is oxidized, producing NADH, FADH2, ATP (or GTP), and CO2 as waste.
What is the role of NADH and FADH2 in the electron transport chain?
NADH and FADH2 donate electrons to the chain, driving ATP synthesis via oxidative phosphorylation.
What is chemiosmosis?
The movement of protons down their gradient through ATP synthase, driving ATP production.
What is the proton-motive force?
The electrochemical gradient created by proton transfer across the mitochondrial membrane.
How many ATP are produced per glucose in cellular respiration?
Approximately 30-32 ATP, depending on conditions and cell type.
Why does fermentation occur?
Fermentation regenerates NAD+ under anaerobic conditions, allowing glycolysis to continue.
What are the products of lactate fermentation?
Lactate and 2 ATP are produced from glucose under anaerobic conditions.
What is the role of modulators in allosteric enzymes?
Modulators bind at regulatory sites, altering enzyme conformation and either activating or inhibiting the enzyme.
What is covalent modification in enzyme regulation?
Covalent modification, such as phosphorylation, alters enzyme activity by adding or removing functional groups.
What is the difference between uncompetitive and competitive inhibition?
Uncompetitive inhibitors bind only to the enzyme-substrate complex, while competitive inhibitors compete with the substrate for the active site.
How is enzyme activity measured?
Enzyme activity is typically measured by the rate of product formation or substrate consumption over time.
Why are zymogens important?
Zymogens prevent premature enzyme activation, which could damage tissues (e.g., trypsinogen in the pancreas).
How do enzymes play a role in drug action?
Enzymes can be drug targets, such as protease inhibitors for HIV or blood thinners like Warfarin.
What are examples of extracellular enzymes?
Digestive enzymes like amylase and proteases break down macromolecules for nutrient absorption.
What is the importance of the preparatory phase of glycolysis?
The preparatory phase invests ATP to phosphorylate glucose, making it more reactive.
What is oxidative decarboxylation?
A reaction where a molecule loses a carbon atom as CO2 while being oxidized, as seen in the citric acid cycle.
How is energy stored during cellular respiration?
Energy is stored in the form of high-energy electron carriers (NADH, FADH2) and ATP.
What is the role of the citric acid cycle in metabolism?
The citric acid cycle oxidizes acetyl-CoA, generating NADH, FADH2, and GTP/ATP for energy production.
What is beta-oxidation?
Beta-oxidation is the process of breaking down fatty acids into acetyl-CoA, NADH, and FADH2 for energy.
What is the role of lactate dehydrogenase in fermentation?
Lactate dehydrogenase converts pyruvate to lactate, regenerating NAD+ for glycolysis under anaerobic conditions.
What is the chemiosmotic theory?
The chemiosmotic theory explains ATP synthesis as driven by a proton gradient across the mitochondrial membrane.
What happens in the electron transport chain?
Electrons are transferred through a series of complexes, driving proton pumping and creating a gradient for ATP production.
What are cofactors and coenzymes?
Cofactors are non-protein molecules required for enzyme activity, including metal ions and organic coenzymes like NAD+.
What is the function of Vitamin B5?
Vitamin B5 is a component of coenzyme A, essential for acetyl-CoA formation in metabolism.
How does magnesium affect enzymes?
Magnesium stabilizes ATP and is required by many enzymes, especially in glycolysis.
What are isoenzymes?
Isoenzymes are enzyme variants that catalyze the same reaction but differ in structure or regulation.
What is the significance of Gibbs free energy in bioenergetics?
Gibbs free energy determines the spontaneity of a reaction, with negative values indicating a spontaneous process.
