Metabolism Flashcards
(27 cards)
What is metabolism?
The sum of all chemical reactions in a cell or organism.
What are the two types of metabolism?
Anabolism (builds, requires energy), Catabolism (breaks down, releases energy).
What is potential energy?
Stored energy (e.g., in chemical bonds).
What does the first law of thermodynamics state?
Energy cannot be created or destroyed, only transformed.
What does the second law of thermodynamics state?
Energy transformations are not 100% efficient; entropy increases.
What is entropy?
A measure of disorder in a system.
What does ΔG indicate in a chemical reaction?
The change in free energy; determines spontaneity.
What type of reaction has ΔG < 0?
Exergonic (releases energy, spontaneous).
How do cells make endergonic reactions proceed?
By coupling them with exergonic reactions (often via ATP).
What is the role of ATP in metabolism?
It acts as an energy currency, coupling reactions to make them proceed.
What happens in oxidation vs. reduction?
Oxidation loses electrons; reduction gains electrons.
How does NADH transfer electrons?
As a hydride ion (2e⁻ + 1H⁺).
Which ETC complex does not pump protons?
Complex II (Succinate Dehydrogenase).
What is the final electron acceptor in the ETC?
Oxygen (O₂ → H₂O).
What does a higher redox potential (E⁰) indicate?
Greater affinity for electrons.
How many protons are pumped by Complex I per NADH?
4 H⁺.
Why is FADH2 lower energy than NADH?
It enters at Complex II (fewer protons pumped).
What is the proton-motive force?
Combined pH and charge gradient driving ATP synthesis.
How many H⁺ are needed for 1 ATP?
4 H⁺.
What inhibits Complex IV?
Cyanide/CO.
How does DNP uncouple oxidative phosphorylation?
Shuttles H⁺ across membrane, dissipating the gradient.
What regulates ATP synthase activity?
ADP/ATP ratio (high ADP → activation).
What are the net products of one CAC cycle?
3 NADH, 1 FADH₂, 1 GTP, 2 CO₂.
Which enzyme catalyzes citrate formation?
Citrate synthase.
