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BIOL 1105 > 7: Energetics of Living Systems > Flashcards

7: Energetics of Living Systems Flashcards

Module 2, Lesson 1

1
Q

The ultimate source of energy used in biological systems is usually…

A

The Sun

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2
Q

Photosynthetic organisms use ____ to store chemical energy.

A

Chemical bonds in sugars

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3
Q

____ is the branch of chemistry concerned with energy changes.

A

Thermodynamics

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4
Q

Energy is defined as…

A

The capacity to do work

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5
Q

____ energy is the energy of motion.

A

Kinetic

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6
Q

____ energy is energy that is stored.

A

Potential

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7
Q

List examples of types of energy.

(nine total)

A
  1. Kinetic
  2. Potential
  3. Chemical
  4. Mechanical
  5. Heat
  6. Sound
  7. Electric Current
  8. Light
  9. Radioactivity
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8
Q

____ is a measurement of energy.

A

Heat

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9
Q

A calorie is defined as the…

A

Heat required to raise the temperature of 1 gram of water by 1 degree Celsius.

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10
Q

Cells convert energy into different forms via…

A

Redox reactions

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11
Q

____ occurs when an atom or molecule loses electron(s).

A

Oxidation

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12
Q

____ occurs when an atom or molecule gains electron(s).

A

Reduction

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13
Q

An atom or molecule that loses electrons is said to have been…

A

Oxidized

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14
Q

An atom or molecule that gains electrons is said to have been…

A

Reduced

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15
Q

True or false:

A particle that has been reduced has greater energy than a particle that has been oxidized.

A

True

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16
Q

____ occur when an oxidation and reduction reaction take place together.

A

Oxidation-reduction reactions
(Redox reactions)

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17
Q

A particle that is oxidized transitions to a ____ energy state.

A

Lower

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18
Q

A particle that is reduced transitions to a ____ energy state.

A

Higher

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19
Q

The first law of thermodynamics states that…

A

Energy cannot be created or destroyed; it can only change from one form to another.

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20
Q

During conversion, some energy is lost as…

A

Heat

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21
Q

True or false:

The total amount of energy in the universe is constant.

A

True

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22
Q

The second law of thermodynamics states that…

A

The entropy (disorder) of the universe is constantly increasing.

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23
Q

True or false:

Energy spontaneously converts from a more stable/less ordered form to a less stable/more ordered form.

A

False

Disorder occurs spontaneously, but an energy input is needed to increase order.

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24
Q

The energy available to do work is called…

A

Gibbs free energy
(G)

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25
Q

G = H - TS, where…

A

G = free energy
H = enthalpy
T = absolute temperature (K)
S = entropy

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26
Q

____ is the energy contained in chemical bonds.

A

Enthalpy

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27
Q

A change in free energy is denoted as…

A

ΔG

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28
Q

We can use ΔG to predict whether…

A

A reaction will occur spontaneously

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29
Q

A reaction in which ΔG is ____ will not occur spontaneously.

A

Positive

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30
Q

The products in a reaction where ΔG is positive will have ____ free energy than the reactants.

A

More

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31
Q

A reaction that does not occur spontaneously is termed…

A

Endergonic

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32
Q

A reaction in which ΔG is ____ will likely occur spontaneously.

A

Negative

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33
Q

The products in a reaction where ΔG is negative will have ____ free energy than the reactants.

A

Less

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34
Q

Reactions that occur spontaneously are termed…

A

Exergonic

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35
Q

True or false:

A spontaneous chemical reaction may still require energy in order to begin.

A

True

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36
Q

The energy needed to start a chemical reaction is called the…

A

Activation energy

37
Q

The ____ of exergonic reactions depends on their activation energy.

38
Q

Reactions with a larger activation energy will have a ____ reaction rate.

39
Q

List two ways to increase the rate of a reaction.

A
  1. Increase the energy of the molecules through heating
  2. Use a catalyst to lower the activiation energy
40
Q

Substances that lower the activation energy of a reaction are called…

41
Q

True or false:

A catalyst can be used to make an endergonic reaction spontaneous.

42
Q

True or false:

Catalysts do not change the proportion of reactants that are converted into products.

43
Q

A catalyzed reaction will have a lower ____ than an uncatalyzed reaction.

A

Activation energy

44
Q

True or false:

The initial and final G values of a reaction are not affected by the presence of a catalyst.

45
Q

____ act as biological catalysts.

46
Q

Like all catalysts, enzymes are neither ____ nor ____ in a reaction.

A

Changed or consumed

47
Q

Most enzymes are ____, but some are ____ molecules.

A

Proteins; RNA

48
Q

The enzymes in a cell specify its ____ and ____ properties.

A

Structural and functional

49
Q

List locations in cells where enzymes may be present.

(five)

A
  1. Cytoplasm
  2. Cytosol
  3. Lumens
  4. Plasma membrane
  5. Organelle membranes
50
Q

____ are globular proteins with a pocket or cleft for substrate binding.

51
Q

An enzyme’s ____ is the location where a specific substrate binds in order for the enzyme to catalyze a reaction.

A

Active site

52
Q

Enzymes lower a reaction’s activation energy by…

A

Applying stress and distorting the chemical bonds

53
Q

The process by which an enzyme changes shape to maximize contact with a substrate is called…

A

Induced fit

54
Q

List three factors that influence enzyme function.

A
  1. Concentration of substrate
  2. Concentration of enzyme
  3. Any chemical or physical condition that affects enzyme structure
55
Q

Conditions that can affect the structure of enzymes include…

(three)

A
  1. Temperature
  2. pH
  3. Regulatory molecules
56
Q

Regulatory molecules that can decrease enzyme activity by binding to it and changing its shape are called…

A

Inhibitors

57
Q

Cells can determine which enzymes are active and which are inactive using…

A

Regulatory molecules

58
Q

____ enzymes can switch between active and inactive states.

A

Allosteric

59
Q

____ inhibitors bind to an enzyme’s active site in place of a substrate.

A

Competitive

60
Q

____ inhibitors bind to an enzyme at a location other than its active site and change its shape to prevent binding.

A

Noncompetitive

61
Q

The location where noncompetitive inhibitors bind to an enzyme is called the…

A

Allosteric site

62
Q

Regulatory molecules that bind to enzymes in order to activate them are called…

A

Enzyme activators

63
Q

The total of all chemical reactions performed by an organism is its…

A

Metabolism

64
Q

The ____ metabolism expends energy to synthesize molecules.

A

Anabolic
(Anabolism)

65
Q

The ____ metabolism harvests energy using the breakdown of molecules.

A

Catabolic
(Catabolism)

66
Q

In ____, chemical reactions occur in sequence, where the product of one reaction becomes the substrate for the next.

A

Biochemical pathways

67
Q

Cells can use ____ to control biochemical pathways.

A

Feedback inhibition

68
Q

During feedback inhibition…

A

The pathway’s end-product binds to the allosteric site on the enzyme that catalyzes the first reaction in the pathway.

69
Q

It is desirable for cells to control biochemical pathways so that…

A

Raw materials and energy aren’t wasted and excess end-product is not produced

70
Q

The main source of chemical potential energy is…

71
Q

ATP contains two ____ bonds, which are unstable and are easily broken during hydrolysis.

A

High-energy

72
Q

Breaking high-energy bonds in ATP provides energy for…

A

Endergonic reactions

73
Q

Most ATP reactions hydrolyze…

A

Only the outermost phosphate

74
Q

When only the outermost phosphate is hydrolyzed, ____ and ____ are produced.

A

ADP and one inorganic phosphate

(ADP stands for “adenosine diphosphate”)

75
Q

Some ATP reactions hydrolyze…

A

Two phosphate groups

76
Q

When two phosphate groups are hydrolyzed, ____ and ____ are produced.

A

AMP and 2 inorganic phosphates

(AMP stands for “adenosine monophosphate”)

77
Q

True or false:

ATP is good at storing energy for long periods of time.

A

False

ATP is best for short-term energy storage. For long-term storage, cells usually use fats or carbohydrates.

78
Q

True or false:

ATP has a very high turnover rate in cells - it is constantly being made and used.

79
Q

How much ATP do cells usually store?

A

Only a few seconds’ worth

80
Q

Cells often use ATP to power coupled reactions, where…

A

An exergonic and endergonic reaction combine so the overall ΔG is negative

81
Q

In a coupled reaction, the exergonic component is often…

A

ATP hydrolysis

82
Q

ATP synthesis depends on energy from ____ reactions.

83
Q

The products of ATP hydrolysis are then used as…

A

Reactants in ATP synthesis

84
Q

____ helps cells control protein activity.

85
Q

Cells control protein activity using a reversible process that involves…

A

Phosphorylation and dephosphorylation

86
Q

The enzyme ____ “turns on” a protein by hydrolyzing ATP, then attaching the released phosphate group to a protein.

87
Q

The enzyme ____ “turns off” a protein by removing the phosphate group from its amino acid sidechain.

A

Phosphotase

88
Q

True or false:

Phosphorylation always causes the target protein to be activated.

A

False

Some target proteins are actually inactivated as a result of phosphorylation.

BIOL 1105 (26 decks)

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