Lecture 3

Question 1

A release of energy can be used to do cellular work:

Answer 1

protein synthesis, folding of proteins, transport across membranes, production of ATP, etc

Question 2

A system:

Answer 2

is any part of the universe we are studying

Question 3

Surroundings:

Answer 3

anything else other than a system

Question 4

Isolated system:

Answer 4

unable to exchange energy or matter with surroundings

Question 5

Closed system:

Answer 5

able to exchage energy, but not matter with surroundings

Question 6

Open system:

Answer 6

able to exchange energy and matter with surroundings

Question 7

Organisms are typically _ systems:

Answer 7

open

Question 8

First Law of Thermodynamics:

Answer 8

total energy of a system and its surroundings is constant. Cannot be created or destroyed, but it can be transferred

Question 9

Second Law of Thermodynamic:

Answer 9

total entropy (disorder) of a system plus its surroundings always increases

Question 10

The exchange of energy during muscle contraction:

Answer 10

the same amount of energy lost to do work must stay constant with the energy absorbed; muscle contraction uses ATP to fuel movement, ATP is generated from metabolic reactions that extract energy from carbohydrates, fats, or proteins

Question 11

The oxidation of palmitic acid (fatty acid):

Answer 11

to CO2 and H2O. The heat released from this reaction is equaly to a change in enthalpy, which is negative is heat is released from the reaction. The energy of the system decreased and was transferred as heat to surroundings.

Question 12

State function:

Answer 12

the overall value dependso nly on the initial and final states of the system, irrespective of the path taken to get there (i.e. enthapy)

Question 13

Enthalpy:

Answer 13

Delta H = Hfinal - Hinitial, the internal energy of a system

Question 14

The direction of a reaction depends on:

Answer 14

1. enthalpy involved in a reaction (forming and breaking bonds)
2. entropy (drive to randomness)

Question 15

3 forms of entropy:

Answer 15

1. ability of molecule to rotate/vibrate/twist around bonds
2. molecules overall scattered or ordered (i.e. cell)
3. larger molecules vs. smaller molecules (less entropy vs. more)

Question 16

Enthalpy and water:

Answer 16

• water close to 0, removing heat will cause the ice to form
• water close to 0, adding heat will cause the ice to melt

Question 17

Reversible reactions:

Answer 17

close to equilibrium = lowest energy state

Question 18

Irreversible reactions:

Answer 18

far from equilibrium = highest energy state

Question 19

Entropy:

Answer 19

Delta S = Delta Ssystem + Delta Ssurroundings

Question 19

Entropy of diffusion

Answer 19

1. high entropy. sucrose is at equilibrium because its NA molecules are distributed randomly throughout the N1 eclls in the initial volume
2. low entropy. when a layer of pure water is added without mxing, the system is not longer at equilibrium. It has become more ordered, with all the occupied cells located in one-half of the solution
3. higher-entropy final state as sucrose and water molecules continue to move randomly, their arrangement becomes more dispered because every cell has an equal chance of being occupied. Eventually, the solution reaches a new equilibrium, with sucrose molecules randomly distributed throughout the larger number of cells (NF) in the final volume

Question 20

Lower entropy vs. higher entropy?

Answer 20

• ice < water
• water < water vapor
• mixture of fruits and yogurt < blended smoothie

Question 21

Delta Suniverse:

Answer 21

must always be >0

Question 22

Entropy change at constant pressure for a system:

Answer 22

• Delta Ssurroundings = - Delta Hsystem/T
• Delta Suniverse = Delta Ssystem - Deleta Hsystem/T

Question 23

Gibbs Free Energy:

Answer 23

the free energy change for a process at constant temperature and pressure

Question 24

Negative enthalpy:

Answer 24

means it loses heat, positive means it takes heat to make the reaciton proceed

Question 25

Positive enthalpy:

Answer 25

takes heat to make the reaction proceed

Question 26

A favoreable reaction (enthalpy and entropy):

Answer 26

a negative enthalpy and a positive entropy

Question 27

Free energy (G):

Answer 27

a measure of useful energy, that is energy capable of doing work

Question 28

If free energy is negative:

Answer 28

reaction proceed to the right spontaneously (exergonic)

Question 29

If free energy is 0:

Answer 29

reaction is at equilibrium and no net changes

Question 30

If free energy is positive:

Answer 30

reaction does not take place spontaneously

Question 31

Spontaneous reaction:

Answer 31

release of energy (exergonic) no need for extra input of energy

Question 32

Non-spontaneous reaction:

Answer 32

need for extra input of energy if you want the reaction to go left to right (enderognic)

Question 33

Fermenration of glucose to ethanol:

Answer 33

favoreable

Question 34

Combustion of ethanol:

Answer 34

favorable

Question 35

Decomposition of nitrogen pentoxide:

Answer 35

favorable

Question 36

If Delta G is small:

Answer 36

direction of reaction may be reversible given changes in concentrations of products or reactants

Question 37

If Delta G is large:

Answer 37

the reaction i sgenerally irreversible in a biological system

Question 38

If Delta G is 0:

Answer 38

the reaction is at equilibrium. The forward and reverse reactions are happening at the same rate

Question 39

The Delta G for a reaction can change if:

Answer 39

concentrations of products or reactants changes

Question 40

Delta G is only fixed under "standard conditions":

Answer 40

* reactants and products at 1.0 M concentration * 25 Celsius * 7.0 pH

Question 41

Delta G knot prime:

Answer 41

the standard free energy change of a reaction and is a fixed number for any specific reaction

Question 42

Free energy of Glycolytic Pathway:

Answer 42

+1.7 kJ/mol endergonic reaction under standard conditions, thus the reverse reaction is favored and equilibrium lies to the left

Question 43

Delta G knot prime at equilibrium:

Answer 43

determines the concentration of reactants and products at equilibrium

Question 44

Every biochemical process must be:

Answer 44

thermodynamically favorable to proceed

Question 45

Reactions can be coupled:

Answer 45

to make biochemical processes favorable

Question 46

Coupled reactions in ATP hydrolysis:

Answer 46

ATP is a high energy phosphate compound that transports phosphoryl groups to acceptor molecules

Question 47

ATP hydrolysis is favorable because:

Answer 47

* forms more resonance * removes repulsive interactions between O groups * forms favorable interactions with water

Question 48

ATP is regenerated:

Answer 48

unfavorable reaction to reattach phosphate (reverse of ATP hydrolysis)

Question 49

Phosphocreatine hydrolysis:

Answer 49

favorable