Exam 1: Chp 3 Flashcards
What is a system in terms of thermodynamics?
What we are concerned with
What is an isolated system in terms of thermodynamics?
Energy and matter is not exchanged with anything outside of the system
What is a closed system in terms of thermodynamics?
Energy is exchanged outside of the system, but matter isn’t
What is a open system in terms of thermodynamics?
Energy and matter is exchanged outside of the system
What is enthalpy in terms of thermodynamics?
Heat content of system that changes form, often by breaking bonds
What is entropy in terms of thermodynamics?
Disorder or randomness
What is Gibbs free energy in terms of thermodynamics?
Amount of energy that can be used to do work
What does -△H mean?
Heat is released by the system
What does +△H mean?
Heat is gained by the system
What does -△S mean?
disorder of the system decreases
What does +△S mean?
disorder of the system of increases
What does +△G mean?
Reaction less likely → system gains free energy
What does -△G mean?
Reaction more likely → system loses free energy
What does △G = 0 mean?
The system is in equilibrium, no free energy is gained or released
What is the first law of thermodynamics?
Total energy of a system and its surroundings must remain constant
Energy cannot be created or destroyed, only change forms
What is the second law of thermodynamics?
Total entropy of a system and its surroundings always increases
Why can order be instilled if it decreases entropy?
Because the act of instilling order requires releasing heat and breaking apart molecules to do work
If △H is negative and △S is positive, what is △G?
△G is negative
If △H is positive and △S is negative, what is △G?
△G is positive
Is △H and △S are both negative or both positive, what is △G?
Either negative or positive, it depends on the values of △H and △S
What is a high energy biomolecule?
A biological molecule that has a lot of energy stored in its bonds
What are 3 typical high energy biomolecules?
ATP, coenzymes, and thioesters
How is △G of hydrolysis impacted by electrostatics?
Hydrolysis breaks a molecule with formal charges into multiple molecules with less formal charges per molecule → relieves electrostatic repulsion → free energy released → △G more negative
How is △G of hydrolysis impacted by resonance?
There are three resonance possibilities on the last phosphate of ATP, after hydrolysis there is three resonance possibilities on the phosphate product and the last phosphate of ADP, resonance stability is increased → stabilization releases free energy → △G more negative
How is △G of hydrolysis impacted by ionization?
Additional negative formal charge added on ADP that stabilizes the partial positive charge of phosphate → stabilization releases free energy → △G more negative
How is △G of hydrolysis impacted by entropy?
2 reagents (ATP and H2O) are broken down into 3 products (ATP + Pi + H) → increases entropy in system → △G more negative
How is △G of hydrolysis impacted by tautomerization?
Some products rearrange into more stable forms after hydrolysis (pyruvate; enol rearranges to keto) → rearrangement releases more free energy → △G more negative
How does pH affect the △G of hydrolysis?
At lower pH, ATP is more stable because H+ stabilizes the negative formal charge on oxygen → less electrostatic repulsion → less free energy released → △G less negative
How do metal ions affect △G of hydrolysis?
More metal ions interact with negative formal charge on oxygen → decrease electrostatic repulsion between P and O → less free energy release → △G less negative
Why are coupled processes so important in biological systems?
They cause necessary unfavorable reactions to occur by coupling it with a favorable reaction to create an over negative △G
