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

Chapter 7 - Metabolism And Energy Flashcards

(86 cards)

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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
_____ change is used to predict whether a system gives off heat
Enthalpy
26
Symbol for enthalpy
Delta H
27
Write the equation that defines enthalpy
Delta H = delta E +P delta V
28
When entropy (delta H) is LESS THAN ZERO, the reaction is…..
Exothermic
29
When a reaction is exothermic, heat is….
Given off/released
30
Can enthalpy reliably predict the direction of reactions?
NO
31
Since enthalpy cannot be used to reliably determine the direction for reactions, what other factor must be used?
Entropy (S)
32
The second law of thermodynamics states that…
The entropy change in the universe for any process is greater than zero
33
When the temperature is high, a change in heat will result in a (large/small) increase in entropy
Small
34
As the temperature decreases, a heat change will produce a (greater/lesser) entropy change
Greater
35
An increase in the number of possible states (increases/decreases) entropy
INCREASES
36
The greater dispersion a reaction produces in the universe, the ___ the entropy
Greater
37
A-B ———> A + B Is the result of this reaction a positive or negative change in entropy for the reaction?
POSITIVE
38
Can we use the entropy of the system alone to determine the direction of a chemical reaction?
NO - we must use a combination of enthalpy and entropy
39
Free energy (G) comes from combining…..
The 1st and 2nd laws of thermodynamics
40
What is the equation for free energy (deltaG)?
DeltaG = deltaH - TdeltaS
41
The second law of thermodynamics applies to…
The universe
42
The free energy equation applies to ______, making it useful for_______
The free energy equation applies to the system under study, making it useful for reactions
43
A reaction is considered FAVORABLE when delta G is less than or greater than zero?
LESS THAN ZERO
44
A reaction in which deltaG is less than zero is said to be….
Exergonic
45
Does bond formation release or require heat?
Releases heat
46
When is a reaction said to be enthalpy driven?
When deltaH is dominant (very large and negative)
47
When is a reaction said to be entropy driven?
When deltaS is very large and positive
48
If a reaction is not possible under defined conditions, will deltaG be less than, greater than, or equal to zero?
Greater than zero, and the reaction will be endergonic
49
An endergonic reaction is NOT POSSIBLE thermodynamically, but the __________ is exergonic
Reverse reaction
50
Explain what it means when deltaG is equal to zero
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
Describe standard conditions
Temperate = 0 degrees Celsius (or 273 K) Pressure = 1 atm
52
Changes in enthalpy, entropy, and free energy at STANDARD STATE are indicated with…..
A superscript degree symbol
53
Write the equation for STANDARD free energy change
deltaG(degree) = -RTlnKeq
54
DeltaG (degree) is _____ related to Keq
DIRECTLY
55
Meaning of the symbol Q
Mass action ratio
56
Under standard conditions, reactions are….
At a steady state
57
Reactions that take place in cells are part of sequences called…
Pathways
58
Metabolic reactions can be divided into 2 groups:
1. Q is only a LITTLE less than Keq (near equilibrium) 2. Q is a LOT less than Keq (metabolically irreversible)
59
When Q is much less than Keq, enzyme concentration is…
Low
60
In a series of 3 reactions, which reaction is the slowest (rate limiting)
1st reaction
61
When we control the 1st reaction of a pathway, what else are we controlling?
The entire pathway
62
ATP is the ____ _____ ____ of metabolism
Central energy intermediate
63
Why is magnesium important in our bodies from a molecular POV?
Magnesium is used to lessen electrical repulsion between neighboring oxygens (example: the phosphate groups in ATP)
64
What is energy coupling?
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
Give an example of a specific energy coupling reaction
Asparagine synthesis reaction
66
NADH is a ___ ___ ___
Principle electron carrier
67
Electron carriers are another energy intermediate between ___ and _____
Catabolism and anabolism
68
What is oxidation?
A loss of one or more electrons from a molecule or functional group
69
What is reduction?
Gain of one or more electrons from a molecule or functional group
70
The processes of oxidation and reduction must occur….
TOGETHER
71
Why must oxidation and reduction occur together?
Because electrons lost from 1 entity must be gained by another
72
Describe the function of NADPH
NADPH is NOT used to generate ATP. It used used to reduce some substances in our body
73
When there are too many oxidizing species in our body, they need to be ____ by ______
Reduced by NADPH
74
Consider the equation: NAD+ + 2e- + H+ ——> NADH The electrons were transferred as a…..
Hydride ion
75
Name some energy intermediates
ATP, NADH, NAD+, GTP, GDP, NADPH, NADP+
76
Energy intermediates can also be known as ______ when viewed in the context of metabolic pathways
MOBILE COFACTORS
77
Mobile cofactors can be thought of as….
Links between or within metabolic sequences
78
What is the most fundamental connection in a pathway view?
Product of one reaction is the substrate of the next
79
____ and ____ connect pathways in _____
NAD+ and NADH connect pathways in PARALLEL
80
NADH and NAD+ connect pathways in parallel. How is this different from cofactors?
Parallel always stays bound to their enzymes
81
Bound cofactors are often called…
Prosthetic groups
82
Prosthetic groups may resemble… HOWEVER…
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
Can prosthetic groups connect separate pathways?
NO
84
IS NAD+ REDUCED OR OXIDIZED TO FORM NADH
Reduced
85
Can enzyme cofactors be derived from amino acids?
NOOOOO
86
What is an enzyme cofactor?
Nonprotein moeity essential for enzyme reactions

Biochem Exam 2 (7 decks)

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