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Biochemistry > Thermodynamics > Flashcards

Thermodynamics Flashcards

1
Q

Bioenergetics:

A

quantitative analysis of how organisms gain and use E

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2
Q

Systems are…

A

what we are studying

- has to have defined boundaries

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3
Q

Types of systems:

A
  • open
  • isolated
  • closed
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4
Q

Open system is…

A

able to exchange both E and matter

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5
Q

Isolated system is…

A

unable to exchange E and matter with surrounding

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6
Q

Closed system is…

A

able to exchange E but not matter

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7
Q

Internal E consists of…

A
  • kinetic E of motion
  • E of rotation
  • E of vibration
  • E stored in chemical bonds
  • E of non-covalent interactions between molecules
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8
Q

T/F: internal E is a function of state of a system

A

T

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9
Q

States of system are defined by..

A
  • temp
  • pressure
  • volume
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10
Q

State functions does not depend on…

A

the pathway the system took

- only depends on current state of system

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11
Q

Examples of state functions:

A
  • internal E
  • enthalpy
  • entropy
  • Gibbs free E
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12
Q

Process functions depend on…

A

pathway between 2 equilibrium states

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13
Q

Examples of process functions:

A
  • temp
  • heat
  • work
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14
Q

Work can’t be a state function b/c…

A

it’s proportional to distance object is moved

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15
Q

Changes in internal E of the system and its surroundings is accomplished by…

A
  • heat transfer to and from system

- work on its surrounding from surroundings

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16
Q

Examples of work forms:

A
  • expansion of system against pressure
  • expansion against surface tension
  • contraction of muscle
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17
Q

Heat (q):

A

(+) q = heat absorbed by system

(-) q = heat given off to surroundings

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18
Q

Work (w):

A

(+) w = work done by system

(-) w = work done on system by surroundings

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19
Q

First law of thermodynamics:

A

E can’t be created or destroyed

delta E = q - w (path independent)

20
Q

Ideal gas law:

A

PV=nRT

21
Q

Enthalpy (H) is a ______ function

A

state

22
Q

What contributes to enthalpy?

A
  • work

- heat

23
Q

T/F: delta H = delta E

A

T b/c volume changes are small in biochem

24
Q

Formula for H at constant pressure:

A

delta H = delta E + P(delta V)

25
Q

Second law of thermodynamics:

A

entropy of isolated system will tend to increase to max value

26
Q

Entropy (S) is the relative degree of…

A

disorder measured by a state function

27
Q

Formula for entropy:

A

S = klnW (k=boltzmann constant)

28
Q

Positive entropy contributions are increased…

A
  • motions
  • rotations
  • degrees of freedom
  • particle #
  • disorder based on state of matter
  • number of molecules
  • spatial distribution of molecules/particles
29
Q

An open system needs a function of both…

A
  • entropy

- enthalpy

30
Q

Gibbs free E (G):

A

state function that combines both entropy and enthalpy

31
Q

Gibbs free E formula:

A

delta G = delta H - T(delta S)

32
Q

Exergonic:

A

thermodynamically favorable (-delta G)

33
Q

Endergonic:

A

thermodynamically unfavorable (+delta G)

34
Q

If delta G = 0, then system is…

A

in equilibrium

35
Q

At low T, delta H dominates and delta G is…

A

positive

36
Q

At high T, T(delta S) dominates and delta G is…

A

negative

37
Q

(-) delta H and (+) delta S =

A

spontaneous (-delta G)

38
Q

(-) delta H and (-) delta S =

A

spontaneous only at low temp

39
Q

(+) delta H and (+) delta S =

A

spontaneous only at high temp

40
Q

(+) delta H and (-) delta S =

A

unspontaneous

41
Q

How to calculate free E:

A

delta G = G(prod) - G(reactants)

42
Q

Standard free E change:

A
  • delta G = RTlnK

K = e^(- delta G/RT)

43
Q

T/F: unfavorable reactions will never be favorable

A

F, can be made thermodynamically favorable by coupling them to favored reactions

44
Q

High E compounds are compounds w/…

A

large negative free E changes

45
Q

Examples of high E compounds:

A
  • phosphate anhydrides
  • enol phosphates
  • thioesters
  • compounds containing N-P bonds
46
Q

Hydrolysis of ATP is…

A

highly exergonic

- delta standard free E = -31 kj/mol

47
Q

Why is hydrolytic release of phosphate high in E?

A
  • resonance stabilization of phosphate products
  • electrostatic repulsion between charged products
  • tautomerization
  • release of proton in buffered solution (pH influences equilibrium)

Biochemistry (9 decks)

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