Lecture 4,5,6 - Thermodynamics and Bioenergetics Flashcards

(34 cards)

1
Q

What is a system

A

The part of the universe that is of interest

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2
Q

What is a surrounding

A

Everything outside of a specified system

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3
Q

What is a boundary

A

a closed 3d surface that separates the system from its surroundings

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4
Q

What is a process

A

When thermodynamic state of a system is changed

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5
Q

What is the first law of thermodynamics

A

Energy can neither be created nor destroyed, but it can be transferred

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6
Q

What is enthalpy change

A

The heat change of a reaction at constant pressure
(slide 7 !! read equation)

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7
Q

What is a closed system (in thermodynamics)

A

can exchange energy (as heat or work) but not matter, with its surroundings

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8
Q

What can be transferred in a thermodynamic system

A

Heat (q)
Work (w)

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9
Q

What is the second law of thermodynamics

A

Any spontaneous process must cause the entropy of the universe to increase

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10
Q

What is entropy (S) (slide 8)

A

The measure of the degree of disorder or randomness in a system

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11
Q

Is enthalpy change indépendant of pathway?

A

Yes (doesn’t matter if we go ABC or ADC)

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12
Q

What do molecules in a system have a natural tendency towards?

A

Randomisation
(S system + S surroundings = maximal)

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13
Q

What is the equation for enthalpy change

A

DH = DU + PDV

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14
Q

What Is enthalpy

A

The total energy content of a system

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15
Q

What is an open system

A

A system that exchanges both matter and energy with its surroundings

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16
Q

What is an isolated system

A

that cannot exchange either matter or energy with its surrounding

17
Q

What is entropy

A

A state function
that measures the degree of disorder or randomness of a system

18
Q

What is the spontaneous diffusion of a dye in water driven by

A

entropy

Entropy is related to the number

of equivalent

arrangements or configurations

of the system.

19
Q

What is the second law of thermodynamics

A

The combined entropy of system and surroundings increases
in a spontaneous process

20
Q

What is Gibbs free energy

A

Gibbs free energy, G, is a state function of the system that incorporates both energy and entropy changes:

G = H – TS

21
Q

What is the Gibbs FE equation

A

Delta G = Delta H - T (Delta S)

22
Q

What is Delta G

A

Change in Gibbs Free energy

a quantitative measure of the driving force of a process at constant temperature and pressure

23
Q

What is the value of G under equilibrium conditions

24
Q

What type of reaction is it if Gibbs >0

A

Endergonic

Forward process is energetically unfavourable
Reverse process proceeds spontaneously

25
What type of reaction is it if Gibbs = 0
System is at equilibrium, there is no further change
26
What type of reaction is it if Gibbs <0
Exergonic Forward process is energetically favourable Forward process proceeds spontaneously
27
What are some factors that affect change in Gibbs free energy
Alter concentrations Couple reactions
28
What is the equation linking concentrations and free energy
Delta G = Delta G(standard conditions) +RT loge [products]/[reactants]
29
What are standard conditions
The º in DGº denotes that reactants and products are all at 1 M concentration, temperature = 298 K, pressure = 1 atmosphere pH=7
30
What is the free energy and concentration equation with equilibrium constant in
Delta G (standard conditions) = -RT ln Keq
31
What is the relationship between change in Gibbs under SC and Equilibrium constant - Keq
DGº < 0 Keq > 1 DGº = 0 Keq = 1 DGº > 0 Keq < 1
32
What do Phosphate esters or nucleotide triphosphate do in reactions
Shuttles of free energy
33
What properties of ATP make it the major energy currency of biochemical processes
Relatively negative DG of ATP hydrolysis derives from highly charged ATP polyphosphate group: relief of electrostatic repulsion when terminal phosphate bond is hydrolysed; inorganic phosphate (Pi) undergoes stabilisation as a resonance hybrid Releases protons into a medium with a low proton concentration ATP is thermodynamically unstable but kinetically stable – ATP hydrolysis has a high activation energy (200 to 400 kJ mol-1) Specific enzymes are required to catalyse phosphoryl group transfer The cell can therefore regulate the distribution of energy carried by ATP by regulating enzymes that act on ATP
34
Ranking of phosphorylated compounds according to their values of DGºʹ for hydrolysis = scale of phosphate transfer potentials.
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