All flashcards
Flashcard 1: What is the role of enzymes in coupled reactions?
Answer: Enzymes lower activation energy, facilitating coupling. Enzymes catalyze both reactions in the coupling mechanism.
Flashcard 2: How do coupled reactions occur in cells?
Answer: They occur via shared intermediates, like ATP. Common molecules like ATP connect energy-releasing and energy-requiring reactions.
Flashcard 3: What is the primary function of ATP in metabolism?
Answer: To transfer energy via phosphate group transfer. Phosphorylation provides energy for cellular work and biosynthesis.
Flashcard 4: Identify the intermediate formed during ATP hydrolysis.
Answer: ADP and inorganic phosphate (Pᵢ). These products carry energy and participate in further reactions.
Flashcard 5: What occurs to ATP in a coupled reaction?
Answer: It is hydrolyzed to ADP and Pᵢ. ATP breakdown releases energy for the coupled process.
Flashcard 6: What is ΔG in the context of coupled reactions?
Answer: Change in Gibbs free energy. Measures energy available for useful work in reactions.
Flashcard 7: What is a phosphorylated intermediate?
Answer: A substrate with added phosphate group from ATP. Activated molecules have increased reactivity for subsequent steps.
Flashcard 8: What is the energy currency of the cell?
Answer: ATP. ATP stores and transfers energy throughout the cell.
Flashcard 9: Which reaction type is driven by ATP hydrolysis?
Answer: Endergonic reactions. ATP provides energy for non-spontaneous biosynthetic processes.
Flashcard 10: Identify a common cellular process that involves coupled reactions.
Answer: Muscle contraction. ATP hydrolysis provides energy for protein conformational changes.
Flashcard 11: How is energy transferred in a coupled reaction?
Answer: Via transfer of phosphoryl groups or electrons. Chemical groups carry energy between reaction sites.
Flashcard 12: What does 'exergonic' mean in terms of Gibbs free energy?
Answer: Exergonic reactions have a negative ΔG. Reactions release energy and occur spontaneously.
Flashcard 13: Identify the role of ATP in coupled reactions.
Answer: ATP acts as an energy carrier linking reactions. ATP transfers energy by releasing phosphate groups to drive reactions.
Flashcard 14: State the relationship between Gibbs free energy and spontaneity.
Answer: Negative ΔG indicates spontaneous reaction. Thermodynamic favorability determines if reactions proceed without input.
Flashcard 15: Which type of reaction is ATP hydrolysis?
Answer: Exergonic reaction. ATP hydrolysis releases energy spontaneously with negative ΔG.
Flashcard 16: What does ATP stand for?
Answer: Adenosine Triphosphate. Universal energy currency with three phosphate groups.
Flashcard 17: How does ATP provide energy to endergonic reactions?
Answer: By phosphorylating substrates, making them more reactive. Phosphate transfer activates molecules for subsequent reactions.
Flashcard 18: What happens to Gibbs free energy in endergonic reactions?
Answer: It increases. Energy is absorbed to form less stable products.
Flashcard 19: What happens to Gibbs free energy in exergonic reactions?
Answer: It decreases. Energy is released as the system becomes more stable.
Flashcard 20: What is the role of coupled reactions in metabolism?
Answer: They facilitate biosynthesis and cellular work. Energy coupling drives essential cellular functions efficiently.
Flashcard 21: Which molecule is regenerated in coupled reactions involving ATP?
Answer: ADP is phosphorylated back to ATP. ATP is regenerated from ADP through phosphorylation reactions.
Flashcard 22: How does ATP hydrolysis affect reaction equilibrium?
Answer: It shifts equilibrium towards product formation. Energy release drives reactions toward completion.
Flashcard 23: What does coupled reaction enable in cellular processes?
Answer: Efficient energy use. Coupling minimizes energy waste in cellular processes.
Flashcard 24: Identify a reaction that is often coupled with ATP hydrolysis.
Answer: Protein synthesis. Translation requires ATP hydrolysis for amino acid assembly.
Flashcard 25: State the equation for ATP hydrolysis.
Answer: ATP + H₂O → ADP + Pᵢ + energy. Hydrolysis breaks ATP bonds, releasing energy for cellular processes.
Flashcard 26: Identify the process that uses ATP to power cellular work.
Answer: Mechanical work like muscle contraction. ATP hydrolysis powers myosin movement along actin filaments.
Flashcard 27: What is the effect of ATP hydrolysis on reaction spontaneity?
Answer: It makes non-spontaneous reactions spontaneous. Energy coupling makes thermodynamically unfavorable reactions proceed.
Flashcard 28: Identify a process where ATP synthesis is coupled to another reaction.
Answer: Oxidative phosphorylation. ATP synthesis is coupled to electron transport chain energy.
Flashcard 29: Which molecule often acts as a common intermediate in coupled reactions?
Answer: ATP. ATP connects exergonic and endergonic processes in metabolism.
Flashcard 30: Identify a common example of a coupled reaction in metabolism.
Answer: Glucose phosphorylation during glycolysis. ATP hydrolysis drives glucose activation in the first glycolytic step.