Energy, Enzymes, and REDOX Flashcards
(118 cards)
1
Q
What are the two main factors that determine the outcome of a chemical reaction in a living cell?
A
Direction and rate
2
Q
What is the term for the ability to do work?
A
Energy
3
Q
What are the two general forms in which energy exists?
A
Kinetic energy and potential energy
4
Q
__ energy is associated with movement, while __ energy is stored energy.
A
Blank 1: Kinetic
Blank 2: Potential
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
6
Q
Direction and __ are the two main factors that determine the fate of a chemical reaction.
A
rate
7
Q
__ is the ability to promote change or do work.
A
Blank 1: Energy or Free energy
8
Q
In broad terms, energy can exist in two forms: __ energy and __ energy.
A
Blank 1: potential
Blank 2: kinetic
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
10
Q
Match each type of energy with the correct biological example: Heat
A
Energy used to maintain a constant body temperature
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
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
13
Q
Match each type of energy with the correct biological example: Mechanical
A
Energy associated with movements due to muscle contraction
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.
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
16
Q
Chemical energy is a form of ______ energy stored in chemical bonds.
A
potential
17
Q
What is entropy?
A
A measure of the amount of disorder in a system
18
Q
What are the two main factors that determine the outcome of a chemical reaction in a living cell?
A
Direction and rate
19
Q
A reaction that releases free energy during product formation is termed a(n) __ reaction.
A
Blank 1: exergonic or spontaneous
20
Q
What is the term for the ability to do work?
A
Energy
21
Q
Concerning Gibbs energy, __ reactions are spontaneous, and __ reactions are not spontaneous.
A
Blank 1: exergonic
Blank 2: endergonic
22
Q
Match each type of energy important in biology with the correct description: Light
A
Electromagnetic radiation visible to the eye
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
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
25
Match each type of energy important in biology with the correct description: Chemical
Potential energy stored in the chemical bonds of molecules
26
Match each type of energy important in biology with the correct description: Electrical/ion gradient
Potential energy stored in a gradient of ions across a membrane
27
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.
The transfer or transformation of energy increases the entropy of a system.
Energy cannot be created or destroyed.
28
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.
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.
29
When a physical system becomes more disordered, the entropy __
increases, rises, escalates, surges, or elevates
30
What molecule is a common energy source for living organisms?
Adenosine triphosphate
31
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.
Exergonic reactions release energy during product formation.
Exergonic reactions are spontaneous.
32
Exergonic reactions have a(n) __ change in free energy, and endergonic reactions have a(n) __ change in free energy.
Blank 1: negative or -
| Blank 2: positive or +
33
Which of the following describes the hydrolysis of ATP?
A water molecule is added to ATP resulting in its breakdown to ADP and inorganic phosphate.
34
True or false: When two reactions are coupled, the first reaction must always be exergonic for both to proceed exergonically.
False
35
A reaction is said to be __ when the addition of free energy from the environment is required for the reaction to proceed.
endergonic, nonspontaneous, or non-spontaneous
36
All cells use a molecule called __ to carry and release energy cyclically.
ATP or adenosine triphosphate
37
Organisms couple __ and __ reactions because many vital cellular processes would not proceed without energy input.
Blank 1: endergonic
| Blank 2: exergonic
38
A reaction that releases free energy during product formation is termed a(n) __ reaction.
exergonic or spontaneous
39
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.
The hydrolysis of ATP has a negative ΔG.
The hydrolysis of ATP is exergonic.
40
When a water molecule is used to remove a phosphate group from ATP, this is called the __ of ATP.
hydrolysis
41
When will an endergonic and exergonic reaction that are coupled proceed spontaneously?
When the net free energy change for both reactions combined is negative (exergonic)
42
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.
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.
43
What is phosphorylation?
The transfer of a phosphate group from one molecule to another
44
Why do organisms couple exergonic and endergonic reactions?
When exergonic and endergonic reactions are coupled, the endergonic reaction will proceed if the net free energy change is negative.
45
Many of the chemical reactions that occur in cells are endergonic. These reactions are possible because they are coupled to:
the hydrolysis of ATP
46
ATP hydrolysis can be used to drive chemical reactions because the hydrolysis of ATP has a ΔG that is:
negative
47
Which of the following describes the hydrolysis of ATP?
A water molecule is added to ATP resulting in its breakdown to ADP and inorganic phosphate.
48
The process of influencing chemical bonds to lower the activation energy of a reaction is called
catalysis.
49
True or false: When two reactions are coupled, the first reaction must always be exergonic for both to proceed exergonically.
False
50
__ are proteins found in living cells that act as catalysts to speed up chemical reactions.
Enzymes or Enzyme catalysts
51
The process by which a phosphate is directly transferred from ATP to glucose is called
phosphorylation
52
Cells commonly use the hydrolysis of ______ to drive chemical reactions.
adenosine triphosphate
53
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.
The hydrolysis of ATP has a negative ΔG.
The hydrolysis of ATP is exergonic.
54
True or false: Thermodynamics governs both the direction of a chemical reaction and its rate.
False
55
What is a catalyst?
An agent that speeds up the rate of a chemical reaction without being permanently changed by the reaction
56
The rates of enzyme-catalyzed reactions are typically millions of times __ than corresponding uncatalyzed reactions.
faster, quicker, higher, greater, or more
57
What is the function of enzymes in living cells?
Enzymes catalyze chemical reactions.
58
What causes the rate of some chemical reactions to be very slow?
Large activation energy
59
What is phosphorylation?
The transfer of a phosphate group from one molecule to another
60
__ energy is the initial input of energy needed to overcome repulsion between molecules in a chemical reaction.
Activation
61
Many of the chemical reactions that occur in cells are endergonic. These reactions are possible because they are coupled to:
the hydrolysis of ATP
62
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.
The chemical reaction can readily proceed.
Bonds are stretched to their limit in the reactant molecules.
63
What is the main factor that can affect the rate of a reaction?
catalysis
64
Catalyzed reactions occur at ______ rate compared to uncatalyzed reactions.
a faster
65
What is, in general, a barrier to the formation of products during a chemical reaction?
Activation energy is required for molecules to reach the transition state and product formation to proceed.
66
In order for molecules to achieve the transition state, __ energy is necessary.
activation
67
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
not change the direction of the reaction
increase the rate of the reaction
68
Once the __ state has been achieved, a chemical reaction can proceed and products can be formed.
transition or activation
69
True or false: Thermodynamics governs both the direction of a chemical reaction and its rate.
False
70
Why do catalysts increase the rate of a chemical reaction?
Catalysts lower the activation energy.
71
What causes the rate of some chemical reactions to be very slow?
Large activation energy
72
An enzyme accelerates the rate of a chemical reaction by
lowering the activation energy
73
Lowering the activation energy of a chemical reaction will:
change the rate of the reaction but will not change its direction
74
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.
The chemical reaction can readily proceed.
Bonds are stretched to their limit in the reactant molecules.
75
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
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
What is the main factor that can affect the rate of a reaction?
catalysis
77
Where does a substrate bind on an enzyme in order for a chemical reaction to take place?
Active site
78
An enzyme speeds up a reaction by lowering the __ energy.
activation
79
What is a substrate?
A reactant molecule that binds to the active site of an enzyme
80
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.
lower; transition
81
During which step of an enzyme-catalyzed reaction does a conformational change occur, resulting in an induced fit?
When substrate binds to the active site
82
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
not change the direction of the reaction
increase the rate of the reaction
83
In a chemical reaction, an enzyme's __ must change before it can catalyze the conversion of reactants to products.
conformation, shape, morphology, structure, or topology
84
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.
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
Enzyme-mediated chemical reactions take place when the substrate molecules bind to the __ __ of an enzyme.
Blank 1: active or activation
| Blank 2: site
86
What is an induced fit between enzyme and substrate?
Conformational changes that cause enzyme and substrate to bind more tightly to one another
87
__, or reactants, are molecules that bind to an enzyme at the active site and are converted to products in chemical reactions.
Substrates
88
Upon contact with the substrate, an enzyme undergoes conformational changes that allows it to bind the substrate more tightly. This phenomenon is called __ __.
Blank 1: induced
| Blank 2: fit
89
True or false: Only after conformational changes cause an induced fit, can substrates be converted to products during an enzyme catalyzed reaction.
True
90
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.
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
True or false: Each step of a metabolic pathway is catalyzed by a specific enzyme.
True
92
When conformational changes cause enzyme and substrate to bind more tightly, this is called __ __.
Blank 1: induced
| Blank 2: fit
93
What is a substrate?
A reactant molecule that binds to the active site of an enzyme
94
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
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
During which step of an enzyme-catalyzed reaction does a conformational change occur, resulting in an induced fit?
When substrate binds to the active site
96
The removal of one or more electrons from an atom or molecule is called:
oxidation
97
In a chemical reaction, an enzyme's __ must change before it can catalyze the conversion of reactants to products.
conformation, shape, morphology, structure, or topology
98
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.
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
During each step of a metabolic pathways, a separate __ is needed to catalyze the reaction.
enzyme
100
What is an induced fit between enzyme and substrate?
Conformational changes that cause enzyme and substrate to bind more tightly to one another
101
What is reduction?
The addition of electrons to an atom or molecule
102
The general term for all types of coordinated sequences of chemical reactions that occur in cells is __ pathways.
metabolic
103
What is oxidation?
The removal of electrons from an atom or molecule
104
__ is the removal of electrons from a molecule, and __ is the addition of electrons to a molecule.
Blank 1: Oxidation
| Blank 2: Reduction
105
What occurs during a redox reaction?
When an atom or molecule is oxidized, the electron that is removed is transferred to another atom or molecule, which is thereby reduced.
106
True or false: Each step of a metabolic pathway is catalyzed by a specific enzyme.
True
107
True or false: The oxidized form of a molecule has less energy than its reduced form.
True
108
The addition of electrons to an atom or molecule is called __.
reduction
109
During the oxidation of glucose, electrons are used to create energy intermediates such as NADH. When NAD+ is ______, it becomes the molecule NADH.
reduced
110
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
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
The removal of one or more electrons from an atom or molecule is called:
oxidation
112
__ __ 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.
Blank 1: Feedback
| Blank 2: Inhibition
113
The term "redox reaction" is short for a(n) __ - __ reaction.
Blank 1: reduction
| Blank 2: oxidation
114
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.
They have fewer electrons and less energy than reduced molecules.
115
When glucose is oxidized, the molecule NAD+ is reduced to __.
NADH
116
The general term for all types of coordinated sequences of chemical reactions that occur in cells is __ pathways.
metabolic
117
When does feedback inhibition occur?
When an product of a metabolic pathway inhibits the activity of an enzyme in the pathway
118
During feedback inhibition, how does binding of the product inhibit enzyme function?
When excess product binds to the allosteric site, it causes a conformational change that prevents further binding of reactants to the active site.
