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Biochem Exam 2 > Chapter 7 - Metabolism And Energy > Flashcards

Chapter 7 - Metabolism And Energy Flashcards

1
Q

Thermodynamics is the science of…

A

Energy changes

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2
Q

What are the 2 origins of the “laws” of thermodynamics?

A

Phenomenological - laws of experience that have no proof other than plausible reasoning
Statistical - using equations for the behavior of extremely large collections of molecules that can be averaged and how regularity

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3
Q

The 2 views arrive at…….

A

Identical conclusions

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4
Q

What is the 1st law of thermodynamics?

A

(Internal) Energy cannot be created or destroyed; only converted from one form to another

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5
Q

What is a system?

A

The portion of the universe that we wish to study

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6
Q

The internal energy is the energy of the..

A

System

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7
Q

A boundary line divides the system from….

A

It’s surrounding

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8
Q

Can exchanges occur between the boundary of the system and its surroundings?

A

YES - both material and no material exchanges can occur

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9
Q

The nonmaterial exchanges across the boundary between a system and its surroundings are..

A

Energy

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10
Q

Energy has 2 distinct forms:

A

Heat and work

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11
Q

Symbol for heat

A

Q

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12
Q

Symbol for work

A

W

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13
Q

When heat is transferred FROM the surroundings TO the system, is q positive or negative?

A

Positive

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14
Q

When work is transferred FROM the surroundings to the system, w is….

A

Positive

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15
Q

Heat and work are both measured in….

A

Joules

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16
Q

Differentiate between temperature and heat

A

Temperature - a measure of how hot an object is relative to another object. Result of the average kinetic energy

Heat - energy EXCHANGE (flow) between between objects of different temperatures ALWAYS in the direction of high to low temperatures

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17
Q

Work can be visualized for molecules as….

A

Translational, vibrational, or rotational energy

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18
Q

After a change in work there is also a change in…

A

The system’s internal energy

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19
Q

State the first law of thermodynamics (as an equation)

A

E=q+w

Where e symbolizes a change in internal energy as a change from one state to another

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20
Q

Each thermodynamic STATE is characterized by….

A

State variables

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21
Q

What are the 4 “state variables”

A

T = temperature
P= pressure
V= volume
N=number of moles

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22
Q

Unlike E, q and w are….

A

Path dependent

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23
Q

Internal free energy is path dependent or independent?

A

Path independent

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24
Q

Where is enthalpy more easily measured?

A

In a laboratory

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25
Q

_____ change is used to predict whether a system gives off heat

A

Enthalpy

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26
Q

Symbol for enthalpy

A

Delta H

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27
Q

Write the equation that defines enthalpy

A

Delta H = delta E +P delta V

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28
Q

When entropy (delta H) is LESS THAN ZERO, the reaction is…..

A

Exothermic

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29
Q

When a reaction is exothermic, heat is….

A

Given off/released

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30
Q

Can enthalpy reliably predict the direction of reactions?

A

NO

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31
Q

Since enthalpy cannot be used to reliably determine the direction for reactions, what other factor must be used?

A

Entropy (S)

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32
Q

The second law of thermodynamics states that…

A

The entropy change in the universe for any process is greater than zero

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33
Q

When the temperature is high, a change in heat will result in a (large/small) increase in entropy

A

Small

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34
Q

As the temperature decreases, a heat change will produce a (greater/lesser) entropy change

A

Greater

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35
Q

An increase in the number of possible states (increases/decreases) entropy

A

INCREASES

36
Q

The greater dispersion a reaction produces in the universe, the ___ the entropy

A

Greater

37
Q

A-B ———> A + B
Is the result of this reaction a positive or negative change in entropy for the reaction?

A

POSITIVE

38
Q

Can we use the entropy of the system alone to determine the direction of a chemical reaction?

A

NO - we must use a combination of enthalpy and entropy

39
Q

Free energy (G) comes from combining…..

A

The 1st and 2nd laws of thermodynamics

40
Q

What is the equation for free energy (deltaG)?

A

DeltaG = deltaH - TdeltaS

41
Q

The second law of thermodynamics applies to…

A

The universe

42
Q

The free energy equation applies to ______, making it useful for_______

A

The free energy equation applies to the system under study, making it useful for reactions

43
Q

A reaction is considered FAVORABLE when delta G is less than or greater than zero?

A

LESS THAN ZERO

44
Q

A reaction in which deltaG is less than zero is said to be….

A

Exergonic

45
Q

Does bond formation release or require heat?

A

Releases heat

46
Q

When is a reaction said to be enthalpy driven?

A

When deltaH is dominant (very large and negative)

47
Q

When is a reaction said to be entropy driven?

A

When deltaS is very large and positive

48
Q

If a reaction is not possible under defined conditions, will deltaG be less than, greater than, or equal to zero?

A

Greater than zero, and the reaction will be endergonic

49
Q

An endergonic reaction is NOT POSSIBLE thermodynamically, but the __________ is exergonic

A

Reverse reaction

50
Q

Explain what it means when deltaG is equal to zero

A

Neither the forward nor reverse reaction is favorable. Another definition of equilibrium. Demonstrates that equilibrium status and free energy change (deltaG) are intimately related

51
Q

Describe standard conditions

A

Temperate = 0 degrees Celsius (or 273 K)
Pressure = 1 atm

52
Q

Changes in enthalpy, entropy, and free energy at STANDARD STATE are indicated with…..

A

A superscript degree symbol

53
Q

Write the equation for STANDARD free energy change

A

deltaG(degree) = -RTlnKeq

54
Q

DeltaG (degree) is _____ related to Keq

A

DIRECTLY

55
Q

Meaning of the symbol Q

A

Mass action ratio

56
Q

Under standard conditions, reactions are….

A

At a steady state

57
Q

Reactions that take place in cells are part of sequences called…

A

Pathways

58
Q

Metabolic reactions can be divided into 2 groups:

A
  1. Q is only a LITTLE less than Keq (near equilibrium)
  2. Q is a LOT less than Keq (metabolically irreversible)
59
Q

When Q is much less than Keq, enzyme concentration is…

A

Low

60
Q

In a series of 3 reactions, which reaction is the slowest (rate limiting)

A

1st reaction

61
Q

When we control the 1st reaction of a pathway, what else are we controlling?

A

The entire pathway

62
Q

ATP is the ____ _____ ____ of metabolism

A

Central energy intermediate

63
Q

Why is magnesium important in our bodies from a molecular POV?

A

Magnesium is used to lessen electrical repulsion between neighboring oxygens (example: the phosphate groups in ATP)

64
Q

What is energy coupling?

A

The joining of an energy process that is endergonic in isolation with one that is exergonic, producing a combined process that is exergonic overall

65
Q

Give an example of a specific energy coupling reaction

A

Asparagine synthesis reaction

66
Q

NADH is a ___ ___ ___

A

Principle electron carrier

67
Q

Electron carriers are another energy intermediate between ___ and _____

A

Catabolism and anabolism

68
Q

What is oxidation?

A

A loss of one or more electrons from a molecule or functional group

69
Q

What is reduction?

A

Gain of one or more electrons from a molecule or functional group

70
Q

The processes of oxidation and reduction must occur….

A

TOGETHER

71
Q

Why must oxidation and reduction occur together?

A

Because electrons lost from 1 entity must be gained by another

72
Q

Describe the function of NADPH

A

NADPH is NOT used to generate ATP. It used used to reduce some substances in our body

73
Q

When there are too many oxidizing species in our body, they need to be ____ by ______

A

Reduced by NADPH

74
Q

Consider the equation:

NAD+ + 2e- + H+ ——> NADH

The electrons were transferred as a…..

A

Hydride ion

75
Q

Name some energy intermediates

A

ATP, NADH, NAD+, GTP, GDP, NADPH, NADP+

76
Q

Energy intermediates can also be known as ______ when viewed in the context of metabolic pathways

A

MOBILE COFACTORS

77
Q

Mobile cofactors can be thought of as….

A

Links between or within metabolic sequences

78
Q

What is the most fundamental connection in a pathway view?

A

Product of one reaction is the substrate of the next

79
Q

____ and ____ connect pathways in _____

A

NAD+ and NADH connect pathways in PARALLEL

80
Q

NADH and NAD+ connect pathways in parallel. How is this different from cofactors?

A

Parallel always stays bound to their enzymes

81
Q

Bound cofactors are often called…

A

Prosthetic groups

82
Q

Prosthetic groups may resemble… HOWEVER…

A

Mobile cofactors. However, the prosthetic groups are attached to the enzyme and MUST BE REGENERATED ALONG WITH THE REST OF THE ENZYME in the course of a single catalytic cycle

83
Q

Can prosthetic groups connect separate pathways?

A

NO

84
Q

IS NAD+ REDUCED OR OXIDIZED TO FORM NADH

A

Reduced

85
Q

Can enzyme cofactors be derived from amino acids?

A

NOOOOO

86
Q

What is an enzyme cofactor?

A

Nonprotein moeity essential for enzyme reactions

Biochem Exam 2 (7 decks)

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