Lecture 2B Flashcards
What is free energy (G) in bioenergetics?
Energy available to do work in a system.
What does a negative ΔG° indicate?
An exergonic reaction that releases free energy.
What does a positive ΔG° indicate?
An endergonic reaction that requires energy input.
What are standard conditions for ΔG°′?
pH 7, 25°C, 1 ATM, 1M reactants/products
How does ΔG° differ from ΔG?
ΔG° is standard, ΔG is actual cellular condition
What is the Gf° of elemental substances?
Zero.
What does negative Gf° signify?
Exergonic formation.
What does positive Gf° signify?
Endergonic formation.
What is activation energy?
Minimum energy needed to start a reaction.
How do enzymes affect activation energy?
They lower the activation energy needed.
What does lysozyme do?
Breaks β(1→4) bonds in peptidoglycan.
List the steps of lysozyme catalysis.
Substrate binding, complex formation, bond strain, cleavage, product release
What is an electron donor?
A substance that loses electrons (oxidized).
What is an electron acceptor?
A substance that gains electrons (reduced).
What does a more negative E₀′ mean?
Better electron donor.
What does a more positive E₀′ mean?
Better electron acceptor.
What is NADH’s redox potential?
−0.32 V.
Is NADH a donor or acceptor?
Electron donor.
Is NAD+ a donor or acceptor?
Electron acceptor.
Name four energy-rich molecules.
PEP, Acetyl-CoA, Acetyl phosphate, Glucose 6-phosphate
How much energy does ATP hydrolysis release?
-31.8 kJ/mol.
Where are all proteins synthesized?
In the cytoplasm.
What targets proteins for membranes?
N-terminal hydrophobic signal sequences.
What do trigger factors do?
Bind nascent proteins and direct secretion.
