Exam 1: Chp 3

Question 1

What is a system in terms of thermodynamics?

Answer 1

What we are concerned with

Question 2

What is an isolated system in terms of thermodynamics?

Answer 2

Energy and matter is not exchanged with anything outside of the system

Question 3

What is a closed system in terms of thermodynamics?

Answer 3

Energy is exchanged outside of the system, but matter isn’t

Question 4

What is a open system in terms of thermodynamics?

Answer 4

Energy and matter is exchanged outside of the system

Question 5

What is enthalpy in terms of thermodynamics?

Answer 5

Heat content of system that changes form, often by breaking bonds

Question 6

What is entropy in terms of thermodynamics?

Answer 6

Disorder or randomness

Question 7

What is Gibbs free energy in terms of thermodynamics?

Answer 7

Amount of energy that can be used to do work

Question 8

What does -△H mean?

Answer 8

Heat is released by the system

Question 9

What does +△H mean?

Answer 9

Heat is gained by the system

Question 10

What does -△S mean?

Answer 10

disorder of the system decreases

Question 11

What does +△S mean?

Answer 11

disorder of the system of increases

Question 12

What does +△G mean?

Answer 12

Reaction less likely → system gains free energy

Question 13

What does -△G mean?

Answer 13

Reaction more likely → system loses free energy

Question 14

What does △G = 0 mean?

Answer 14

The system is in equilibrium, no free energy is gained or released

Question 15

What is the first law of thermodynamics?

Answer 15

Total energy of a system and its surroundings must remain constant
Energy cannot be created or destroyed, only change forms

Question 16

What is the second law of thermodynamics?

Answer 16

Total entropy of a system and its surroundings always increases

Question 17

Why can order be instilled if it decreases entropy?

Answer 17

Because the act of instilling order requires releasing heat and breaking apart molecules to do work

Question 18

If △H is negative and △S is positive, what is △G?

Answer 18

△G is negative

Question 19

If △H is positive and △S is negative, what is △G?

Answer 19

△G is positive

Question 20

Is △H and △S are both negative or both positive, what is △G?

Answer 20

Either negative or positive, it depends on the values of △H and △S

Question 21

What is a high energy biomolecule?

Answer 21

A biological molecule that has a lot of energy stored in its bonds

Question 22

What are 3 typical high energy biomolecules?

Answer 22

ATP, coenzymes, and thioesters

Question 23

How is △G of hydrolysis impacted by electrostatics?

Answer 23

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

Question 24

How is △G of hydrolysis impacted by resonance?

Answer 24

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

Question 25

How is △G of hydrolysis impacted by ionization?

Answer 25

Additional negative formal charge added on ADP that stabilizes the partial positive charge of phosphate → stabilization releases free energy → △G more negative

Question 26

How is △G of hydrolysis impacted by entropy?

Answer 26

2 reagents (ATP and H2O) are broken down into 3 products (ATP + Pi + H) → increases entropy in system → △G more negative

Question 27

How is △G of hydrolysis impacted by tautomerization?

Answer 27

Some products rearrange into more stable forms after hydrolysis (pyruvate; enol rearranges to keto) → rearrangement releases more free energy → △G more negative

Question 28

How does pH affect the △G of hydrolysis?

Answer 28

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

Question 29

How do metal ions affect △G of hydrolysis?

Answer 29

More metal ions interact with negative formal charge on oxygen → decrease electrostatic repulsion between P and O → less free energy release → △G less negative

Question 30

Why are coupled processes so important in biological systems?

Answer 30

They cause necessary unfavorable reactions to occur by coupling it with a favorable reaction to create an over negative △G