mega set
Flashcards: Biochemistry Foundations & Thermodynamics
Front: What is the definition of an equilibrium constant (K)? Back: It is the ratio of the concentration of products over the concentration of reactants ([Products]/[Reactants]).
Front: What does a large equilibrium constant (K) signify? Back: It indicates a reaction that produces a high concentration of products, essentially going toward completion.
Front: In a metabolic pathway, how can an unfavorable reaction be driven forward? Back: By coupling it to a subsequent highly favorable reaction that depletes the product (Le Chatelier’s principle).
Front: Distinguish between anabolic and catabolic pathways. Back: Anabolic pathways synthesize molecules and require energy, while catabolic pathways degrade molecules and release energy.
Front: Which molecule liberates the LEAST free energy when hydrolyzed: ATP, PEP, PPi, or Glucose-6-phosphate? Back: Glucose-6-phosphate.
Front: Name two reasons why ATP hydrolysis products are more stable than ATP itself. Back: Relief of charge-charge repulsions and resonance stabilization of the products.
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Flashcards: Water, Polarity & Noncovalent Interactions
Front: Why is water considered a polar molecule? Back: It has a net dipole moment due to the difference in electronegativity between oxygen and hydrogen and its bent shape.
Front: Why is CO2 nonpolar despite having polar bonds? Back: It is a linear molecule, so the individual bond dipoles cancel each other out.
Front: What defines a hydrogen bond "donor"? Back: The atom (O or N) covalently bonded to the hydrogen atom.
Front: What defines a hydrogen bond "acceptor"? Back: The atom with a lone pair of electrons that interacts with the hydrogen atom.
Front: How many hydrogen bonds can a single water molecule form? Back: Four.
Front: What is a "salt bridge" in protein structure? Back: An electrostatic (ionic) interaction between oppositely charged groups.
Front: How does the dielectric constant (D) affect the strength of an ionic bond? Back: A lower dielectric constant (like hexane’s D=2) makes ionic bonds much stronger than in water (D=80).
Front: What is "pi stacking"? Back: A weak interaction between the electron clouds above and below aromatic rings, critical for DNA stability.
Front: Define an "amphipathic" molecule. Back: A molecule containing both polar (hydrophilic) and nonpolar (hydrophobic) regions.
Front: What happens to entropy (ΔS) when hydrophobic molecules aggregate in water? Back: The entropy of the system decreases (becomes more negative).
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Flashcards: Acid-Base Chemistry & Buffers
Front: What is the physiological pH range for human blood? Back: 7.35 to 7.45.
Front: What is the definition of a Bronsted-Lowry acid? Back: A molecule that acts as a proton (H+) donor.
Front: What is an "amphoteric" substance? Back: A substance, like water, that can act as either an acid or a base.
Front: What does the pKa value measure? Back: It is a measure of acid strength; a lower pKa indicates a stronger acid.
Front: Write the Henderson-Hasselbalch equation. Back: pH=pKa+log([A−]/[HA]).
Front: At what point on a titration curve is the pH equal to the pKa? Back: At the midpoint of the titration where the concentration of the weak acid [HA] equals its conjugate base [A−].
Front: What is the effective buffering range for a weak acid? Back: pKa±1 pH unit.
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Flashcards: Physiological Regulation & Phosphate
Front: How does hyperventilation affect blood pH? Back: It decreases CO2 levels, shifting the equilibrium to decrease H+, which increases pH (alkalosis).
Front: How does hypoventilation (slow breathing) affect blood pH? Back: it increases CO2 levels, shifting the equilibrium to increase H+, which decreases pH (acidosis).
Front: What is the predominant buffer system in human blood? Back: The bicarbonate system (CO2/H2CO3/HCO3−).
Front: Why is the pKa2 of phosphate (7.20) physiologically important? Back: It is very close to the physiological pH of 7.40, allowing it to function as a potential buffer in cells.
Front: What is the approximate charge on a phosphate molecule at pH 7.40? Back: Approximately -1.61.
Front: Why can high phosphate concentrations be problematic in cells? Back: Phosphate can form insoluble precipitates with ions like Calcium (Ca2+).