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Bio 181 > Energy, Enzymes, and REDOX > Flashcards

Energy, Enzymes, and REDOX Flashcards

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1
Q

What are the two main factors that determine the outcome of a chemical reaction in a living cell?

A

Direction and rate

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2
Q

What is the term for the ability to do work?

A

Energy

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3
Q

What are the two general forms in which energy exists?

A

Kinetic energy and potential energy

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4
Q

__ energy is associated with movement, while __ energy is stored energy.

A

Blank 1: Kinetic

Blank 2: Potential

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5
Q

The energy contained within covalent bonds in molecules is a type of potential energy called __ energy.

A

Blank 1: chemical, chemical potential, or chemical energy

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6
Q

Direction and __ are the two main factors that determine the fate of a chemical reaction.

A

rate

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7
Q

__ is the ability to promote change or do work.

A

Blank 1: Energy or Free energy

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8
Q

In broad terms, energy can exist in two forms: __ energy and __ energy.

A

Blank 1: potential

Blank 2: kinetic

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9
Q

Match each type of energy with the correct biological example: Light

A

Energy used to reduce carbon and produce organic molecules during photosynthesis

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10
Q

Match each type of energy with the correct biological example: Heat

A

Energy used to maintain a constant body temperature

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11
Q

Match each type of energy with the correct biological example: Chemical

A

Energy stored in the covalent bonds of organic molecules such as glucose and ATP

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12
Q

Match each type of energy with the correct biological example: Electrical/ion gradient

A

Energy used to drive ATP synthesis during oxidative phosphorylation

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13
Q

Match each type of energy with the correct biological example: Mechanical

A

Energy associated with movements due to muscle contraction

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14
Q

Which of the following describes the major difference between kinetic and potential energy?

  • Potential energy is the energy of motion and kinetic energy is associated with the position of an object.
  • Kinetic energy is the energy of motion and potential energy is associated with the position of an object.
  • Kinetic energy is stored in chemical bonds and potential energy is associated with the position of an object.
A

Kinetic energy is the energy of motion and potential energy is associated with the position of an object.

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15
Q

The laws of thermodynamics state that __ cannot be created or destroyed and that the __ of a system tends to increase.

A

Blank 1: energy

Blank 2: entropy or disorder

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16
Q

Chemical energy is a form of ______ energy stored in chemical bonds.

A

potential

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17
Q

What is entropy?

A

A measure of the amount of disorder in a system

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18
Q

What are the two main factors that determine the outcome of a chemical reaction in a living cell?

A

Direction and rate

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19
Q

A reaction that releases free energy during product formation is termed a(n) __ reaction.

A

Blank 1: exergonic or spontaneous

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20
Q

What is the term for the ability to do work?

A

Energy

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21
Q

Concerning Gibbs energy, __ reactions are spontaneous, and __ reactions are not spontaneous.

A

Blank 1: exergonic

Blank 2: endergonic

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22
Q

Match each type of energy important in biology with the correct description: Light

A

Electromagnetic radiation visible to the eye

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23
Q

Match each type of energy important in biology with the correct description: Heat

A

Kinetic energy that can be transferred between two objects due to a difference in temperature

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24
Q

Match each type of energy important in biology with the correct description: Mechanical

A

Energy possessed by an object due to its motion

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25
Q

Match each type of energy important in biology with the correct description: Chemical

A

Potential energy stored in the chemical bonds of molecules

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26
Q

Match each type of energy important in biology with the correct description: Electrical/ion gradient

A

Potential energy stored in a gradient of ions across a membrane

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27
Q

What do the two laws of thermodynamics state?

  • The transfer or transformation of energy increases the entropy of a system.
  • Energy can be created from organic molecules.
  • Energy cannot be created or destroyed.
  • Only exergonic reactions can occur.
A

The transfer or transformation of energy increases the entropy of a system.

Energy cannot be created or destroyed.

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28
Q

Which of the following statements about endergonic reactions are true?

  • Endergonic reactions are not spontaneous.
  • Endergonic reactions have a positive change in free energy.
  • Endergonic reactions require the addition of free energy.
  • Endergonic reactions release free energy.
  • The products have a higher free energy than the reactants.
A

Endergonic reactions are not spontaneous.

Endergonic reactions have a positive change in free energy.

Endergonic reactions require the addition of free energy.

The products have a higher free energy than the reactants.

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29
Q

When a physical system becomes more disordered, the entropy __

A

increases, rises, escalates, surges, or elevates

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30
Q

What molecule is a common energy source for living organisms?

A

Adenosine triphosphate

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31
Q

Which of the following statements regarding exergonic reactions are true?

  • Exergonic reactions release energy during product formation.
  • Exergonic reactions have a positive change in free energy.
  • Exergonic reactions are spontaneous.
  • The products of an exergonic reaction have a higher free energy than the reactants.
A

Exergonic reactions release energy during product formation.

Exergonic reactions are spontaneous.

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32
Q

Exergonic reactions have a(n) __ change in free energy, and endergonic reactions have a(n) __ change in free energy.

A

Blank 1: negative or -

Blank 2: positive or +

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33
Q

Which of the following describes the hydrolysis of ATP?

A

A water molecule is added to ATP resulting in its breakdown to ADP and inorganic phosphate.

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34
Q

True or false: When two reactions are coupled, the first reaction must always be exergonic for both to proceed exergonically.

A

False

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35
Q

A reaction is said to be __ when the addition of free energy from the environment is required for the reaction to proceed.

A

endergonic, nonspontaneous, or non-spontaneous

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36
Q

All cells use a molecule called __ to carry and release energy cyclically.

A

ATP or adenosine triphosphate

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37
Q

Organisms couple __ and __ reactions because many vital cellular processes would not proceed without energy input.

A

Blank 1: endergonic

Blank 2: exergonic

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38
Q

A reaction that releases free energy during product formation is termed a(n) __ reaction.

A

exergonic or spontaneous

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39
Q

The hydrolysis of ATP can be used to drive a chemical reaction that cannot occur spontaneously because:

  • The hydrolysis of ATP requires energy.
  • The hydrolysis of ATP has a negative ΔG.
  • The hydrolysis of ATP is exergonic.
  • The hydrolysis of ATP is endergonic.
A

The hydrolysis of ATP has a negative ΔG.

The hydrolysis of ATP is exergonic.

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40
Q

When a water molecule is used to remove a phosphate group from ATP, this is called the __ of ATP.

A

hydrolysis

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41
Q

When will an endergonic and exergonic reaction that are coupled proceed spontaneously?

A

When the net free energy change for both reactions combined is negative (exergonic)

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42
Q

Which of the following statements about endergonic reactions are true?

  • The products have a higher free energy than the reactants.
  • Endergonic reactions have a positive change in free energy.
  • Endergonic reactions are not spontaneous.
  • Endergonic reactions require the addition of free energy.
  • Endergonic reactions release free energy.
A

The products have a higher free energy than the reactants.

Endergonic reactions have a positive change in free energy.

Endergonic reactions are not spontaneous.

Endergonic reactions require the addition of free energy.

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43
Q

What is phosphorylation?

A

The transfer of a phosphate group from one molecule to another

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44
Q

Why do organisms couple exergonic and endergonic reactions?

A

When exergonic and endergonic reactions are coupled, the endergonic reaction will proceed if the net free energy change is negative.

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45
Q

Many of the chemical reactions that occur in cells are endergonic. These reactions are possible because they are coupled to:

A

the hydrolysis of ATP

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46
Q

ATP hydrolysis can be used to drive chemical reactions because the hydrolysis of ATP has a ΔG that is:

A

negative

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47
Q

Which of the following describes the hydrolysis of ATP?

A

A water molecule is added to ATP resulting in its breakdown to ADP and inorganic phosphate.

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48
Q

The process of influencing chemical bonds to lower the activation energy of a reaction is called

A

catalysis.

49
Q

True or false: When two reactions are coupled, the first reaction must always be exergonic for both to proceed exergonically.

A

False

50
Q

__ are proteins found in living cells that act as catalysts to speed up chemical reactions.

A

Enzymes or Enzyme catalysts

51
Q

The process by which a phosphate is directly transferred from ATP to glucose is called

A

phosphorylation

52
Q

Cells commonly use the hydrolysis of ______ to drive chemical reactions.

A

adenosine triphosphate

53
Q

The hydrolysis of ATP can be used to drive a chemical reaction that cannot occur spontaneously because:

  • The hydrolysis of ATP is endergonic.
  • The hydrolysis of ATP has a negative ΔG.
  • The hydrolysis of ATP requires energy.
  • The hydrolysis of ATP is exergonic.
A

The hydrolysis of ATP has a negative ΔG.

The hydrolysis of ATP is exergonic.

54
Q

True or false: Thermodynamics governs both the direction of a chemical reaction and its rate.

A

False

55
Q

What is a catalyst?

A

An agent that speeds up the rate of a chemical reaction without being permanently changed by the reaction

56
Q

The rates of enzyme-catalyzed reactions are typically millions of times __ than corresponding uncatalyzed reactions.

A

faster, quicker, higher, greater, or more

57
Q

What is the function of enzymes in living cells?

A

Enzymes catalyze chemical reactions.

58
Q

What causes the rate of some chemical reactions to be very slow?

A

Large activation energy

59
Q

What is phosphorylation?

A

The transfer of a phosphate group from one molecule to another

60
Q

__ energy is the initial input of energy needed to overcome repulsion between molecules in a chemical reaction.

A

Activation

61
Q

Many of the chemical reactions that occur in cells are endergonic. These reactions are possible because they are coupled to:

A

the hydrolysis of ATP

62
Q

What happens when the transition state is reached?

  • The chemical reaction can readily proceed.
  • Repulsion between the reactants is maximized.
  • Bonds are stretched to their limit in the reactant molecules.
  • A further input of activation energy is required.
A

The chemical reaction can readily proceed.

Bonds are stretched to their limit in the reactant molecules.

63
Q

What is the main factor that can affect the rate of a reaction?

A

catalysis

64
Q

Catalyzed reactions occur at ______ rate compared to uncatalyzed reactions.

A

a faster

65
Q

What is, in general, a barrier to the formation of products during a chemical reaction?

A

Activation energy is required for molecules to reach the transition state and product formation to proceed.

66
Q

In order for molecules to achieve the transition state, __ energy is necessary.

A

activation

67
Q

If the activation energy of a chemical reaction is lowered it will:

  • not change the direction of the reaction
  • decrease the rate of the reaction
  • change the direction of the reaction
  • increase the rate of the reaction
A

not change the direction of the reaction

increase the rate of the reaction

68
Q

Once the __ state has been achieved, a chemical reaction can proceed and products can be formed.

A

transition or activation

69
Q

True or false: Thermodynamics governs both the direction of a chemical reaction and its rate.

A

False

70
Q

Why do catalysts increase the rate of a chemical reaction?

A

Catalysts lower the activation energy.

71
Q

What causes the rate of some chemical reactions to be very slow?

A

Large activation energy

72
Q

An enzyme accelerates the rate of a chemical reaction by

A

lowering the activation energy

73
Q

Lowering the activation energy of a chemical reaction will:

A

change the rate of the reaction but will not change its direction

74
Q

What happens when the transition state is reached?

  • The chemical reaction can readily proceed.
  • Repulsion between the reactants is maximized.
  • Bonds are stretched to their limit in the reactant molecules.
  • A further input of activation energy is required.
A

The chemical reaction can readily proceed.

Bonds are stretched to their limit in the reactant molecules.

75
Q

How do enzymes lower the activation energy of a chemical reaction?

  • Enzymes input energy needed to reach transition state.
  • Enzymes can bring reactants closer together.
  • When reactants are bound to enzymes, they can be strained, making it easier to achieve the transition state.
  • Enzymes facilitate chemical reactions by removing excess heat
A

Enzymes can bring reactants closer together.

When reactants are bound to enzymes, they can be strained, making it easier to achieve the transition state.

76
Q

What is the main factor that can affect the rate of a reaction?

A

catalysis

77
Q

Where does a substrate bind on an enzyme in order for a chemical reaction to take place?

A

Active site

78
Q

An enzyme speeds up a reaction by lowering the __ energy.

A

activation

79
Q

What is a substrate?

A

A reactant molecule that binds to the active site of an enzyme

80
Q

Enzymes ______ the activation energy of a reaction to a point where a small amount of available heat can push the reactants to a(n) ______ state.

A

lower; transition

81
Q

During which step of an enzyme-catalyzed reaction does a conformational change occur, resulting in an induced fit?

A

When substrate binds to the active site

82
Q

If the activation energy of a chemical reaction is lowered it will:

  • not change the direction of the reaction
  • increase the rate of the reaction
  • change the direction of the reaction
  • decrease the rate of the reaction
A

not change the direction of the reaction

increase the rate of the reaction

83
Q

In a chemical reaction, an enzyme’s __ must change before it can catalyze the conversion of reactants to products.

A

conformation, shape, morphology, structure, or topology

84
Q

How can catalysts increase the rate of chemical reactions?

  • Catalysts input heat into a system to allow chemical reactions to proceed.
  • Catalysts can change an endergonic reaction into an exergonic reaction.
  • Catalysts can arrange molecules in the proper orientation to allow for the formation of covalent bonds.
  • Catalysts can position the reactants so that they can interact with each other.
A

Catalysts can arrange molecules in the proper orientation to allow for the formation of covalent bonds.

Catalysts can position the reactants so that they can interact with each other.

85
Q

Enzyme-mediated chemical reactions take place when the substrate molecules bind to the __ __ of an enzyme.

A

Blank 1: active or activation

Blank 2: site

86
Q

What is an induced fit between enzyme and substrate?

A

Conformational changes that cause enzyme and substrate to bind more tightly to one another

87
Q

__, or reactants, are molecules that bind to an enzyme at the active site and are converted to products in chemical reactions.

A

Substrates

88
Q

Upon contact with the substrate, an enzyme undergoes conformational changes that allows it to bind the substrate more tightly. This phenomenon is called __ __.

A

Blank 1: induced

Blank 2: fit

89
Q

True or false: Only after conformational changes cause an induced fit, can substrates be converted to products during an enzyme catalyzed reaction.

A

True

90
Q

How do enzymes lower the activation energy of a chemical reaction?

  • Enzymes facilitate chemical reactions by removing excess heat
  • Enzymes input energy needed to reach transition state.
  • When reactants are bound to enzymes, they can be strained, making it easier to achieve the transition state.
  • Enzymes can bring reactants closer together.
A

When reactants are bound to enzymes, they can be strained, making it easier to achieve the transition state.

Enzymes can bring reactants closer together.

91
Q

True or false: Each step of a metabolic pathway is catalyzed by a specific enzyme.

A

True

92
Q

When conformational changes cause enzyme and substrate to bind more tightly, this is called __ __.

A

Blank 1: induced

Blank 2: fit

93
Q

What is a substrate?

A

A reactant molecule that binds to the active site of an enzyme

94
Q

Which of the following statements regarding metabolic pathways are true?

  • they do not stop once they begin
  • can result in the synthesis of larger molecules from smaller molecules
  • the same enzyme catalyzes all the steps in the pathway
  • can result in the breakdown of large molecules
  • the product of one reaction becomes the substrate for the next reaction
  • a different enzyme catalyzes each step
A

can result in the synthesis of larger molecules from smaller molecules

can result in the breakdown of large molecules

the product of one reaction becomes the substrate for the next reaction

a different enzyme catalyzes each step

95
Q

During which step of an enzyme-catalyzed reaction does a conformational change occur, resulting in an induced fit?

A

When substrate binds to the active site

96
Q

The removal of one or more electrons from an atom or molecule is called:

A

oxidation

97
Q

In a chemical reaction, an enzyme’s __ must change before it can catalyze the conversion of reactants to products.

A

conformation, shape, morphology, structure, or topology

98
Q

What are differences between reduction and oxidation?

  • Oxidation will decrease the net charge of a molecule while reduction will increase the net charge.
  • Oxidation is the addition of electrons and reduction is the removal of electrons.
  • Reduction will decrease the net charge of a molecule while oxidation will increase the net charge.
  • Reduction is the addition of electrons and oxidation is the removal of electrons.
A

Reduction will decrease the net charge of a molecule while oxidation will increase the net charge.

Reduction is the addition of electrons and oxidation is the removal of electrons.

99
Q

During each step of a metabolic pathways, a separate __ is needed to catalyze the reaction.

A

enzyme

100
Q

What is an induced fit between enzyme and substrate?

A

Conformational changes that cause enzyme and substrate to bind more tightly to one another

101
Q

What is reduction?

A

The addition of electrons to an atom or molecule

102
Q

The general term for all types of coordinated sequences of chemical reactions that occur in cells is __ pathways.

A

metabolic

103
Q

What is oxidation?

A

The removal of electrons from an atom or molecule

104
Q

__ is the removal of electrons from a molecule, and __ is the addition of electrons to a molecule.

A

Blank 1: Oxidation

Blank 2: Reduction

105
Q

What occurs during a redox reaction?

A

When an atom or molecule is oxidized, the electron that is removed is transferred to another atom or molecule, which is thereby reduced.

106
Q

True or false: Each step of a metabolic pathway is catalyzed by a specific enzyme.

A

True

107
Q

True or false: The oxidized form of a molecule has less energy than its reduced form.

A

True

108
Q

The addition of electrons to an atom or molecule is called __.

A

reduction

109
Q

During the oxidation of glucose, electrons are used to create energy intermediates such as NADH. When NAD+ is ______, it becomes the molecule NADH.

A

reduced

110
Q

Which of the following statements regarding metabolic pathways are true?

  • the product of one reaction becomes the substrate for the next reaction
  • the same enzyme catalyzes all the steps in the pathway
  • can result in the breakdown of large molecules
  • can result in the synthesis of larger molecules from smaller molecules
  • they do not stop once they begin
  • a different enzyme catalyzes each step
A

the product of one reaction becomes the substrate for the next reaction

can result in the breakdown of large molecules

can result in the synthesis of larger molecules from smaller molecules

a different enzyme catalyzes each step

111
Q

The removal of one or more electrons from an atom or molecule is called:

A

oxidation

112
Q

__ __ is an example of noncompetitive inhibition involved in the regulation of biochemical pathways; usually the end product of a series of reactions affects the first enzyme in the series to shut down the pathway.

A

Blank 1: Feedback

Blank 2: Inhibition

113
Q

The term “redox reaction” is short for a(n) __ - __ reaction.

A

Blank 1: reduction

Blank 2: oxidation

114
Q

Which of the following statements about oxidized molecules is true?

  • They have fewer electrons but more energy than reduced molecules.
  • They have more electrons but less energy than reduced molecules.
  • They have more electrons and more energy than reduced molecules.
  • They have fewer electrons and less energy than reduced molecules.
A

They have fewer electrons and less energy than reduced molecules.

115
Q

When glucose is oxidized, the molecule NAD+ is reduced to __.

A

NADH

116
Q

The general term for all types of coordinated sequences of chemical reactions that occur in cells is __ pathways.

A

metabolic

117
Q

When does feedback inhibition occur?

A

When an product of a metabolic pathway inhibits the activity of an enzyme in the pathway

118
Q

During feedback inhibition, how does binding of the product inhibit enzyme function?

A

When excess product binds to the allosteric site, it causes a conformational change that prevents further binding of reactants to the active site.

Bio 181 (18 decks)

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