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Cellular Biology 201 UNCW > Chapter 8 An Introduction To Metabolism > Flashcards

Chapter 8 An Introduction To Metabolism Flashcards

1
Q

Which of the following is changed by the presence of an enzyme in a reaction?

A

The activation energy.

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2
Q

Which of these statements about enzyme inhibitors is true?

A

The action of inhibitors may be reversible or irreversible

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3
Q

The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of _____________.

A

Allosteric regulation

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4
Q

An exergonic reaction ________________ free energy, and an end ergo in reaction ________________ free energy.

A

Releases; Absorbs

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5
Q

The primary manner in which cells manage their energy resources in order to do wok is called energy coupling. Which of the following statements accurately defines energy coupling?

A

Exergonic reactions drive endergonic reaction.

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6
Q

Which of the following statements about the active site of an enzyme is correct?

A

THe active site may resemble a groove or pocket in the surface of a protein into which the substrate fits.

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7
Q

How does ATP drive mechanical work inside a cell?

A

By binding to motor proteins

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8
Q

What would the aloe of DELTA S be for a chemical reaction in which a molecule is broken down into smaller components?

A

Positive

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9
Q

In general, the hydrolysis of ATP drives cellular work by ___________________.

A

Releasing free energy that can be coupled to other reactions

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10
Q

Which of the following statements about enzymes is true?

A

Enzymes speed up the rate of the reaction without changing the DELTA G for the reaction.

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11
Q

At low pH, a particular enzyme catalyzes a reaction at a high rate. At neutral pH, the enzyme is completely inactive. What statement best explains the difference in how pH affects the function of this enzyme?

A

The enzyme is adapted for low pH but is denatured at neutral pH, leaving it nonfunctional.

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12
Q

Which of the following reactions would be endergonic?

A

Glucose + Fructose = Sucrose

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13
Q

What best characterizes the role of ATP in cellular metabolism?

A

The free energy released by ATP hydrolysis that may be coupled to an endergonic process via the formation of a phosphorylated intermediate.

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14
Q

At low temperatures, a particular enzyme catalyzes a reaction, but at a slow rate. At high temperatures, the enzyme is completely inactive. What statement best explains the difference in how temperature affects the function of this enzyme?

A

At low temperatures, there is not enough free energy for the enzyme to function at a high rate, and at high temperatures, the enzyme is remastered, leaving it nonfunctional.

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15
Q

ATP allosterically inhibits enzymes in ATP-producing pathways. The result of this is called __________________.

A

Feedback inhibition

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16
Q

Cells use ATP constantly, but ATP is considered a renewable resource. What process makes this possible?

A

ATP can be regenerated by the addition of a phosphate group to ADP.

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17
Q

Which of the following statements is correct regarding kinetic and potential energy?

A

Kinetic energy is associated with the relative motion of abject, and potential energy is the energy that matter possesses because of its location or structure.

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18
Q

As ATP begins to build up in a cell, metabolism slows down. How does this happen?

A

APT acts as an allosteric inhibitor to many of the enzymes involved in metabolism, the us slowing their function.

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19
Q

Which of the following statements is correct regarding competitive and noncompetitive enzyme inhibitors?

A

Competitive inhibitors bind to the active site of an enzyme while noncompetitive inhibitors bind to an enzyme away form the active site.

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20
Q

How does ATP drive transport work inside a cell?

A

By phosphorylation a transport protein.

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21
Q

Which of the following is an example of the second law of thermodynamics as it applies to biological reactions?

A

The aerobic respiration of one molecule of glucose produces six molecules each of carbon dioxide and water.

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22
Q

Enzyme activity is affected by pH because ___________________.

A

High or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site.

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23
Q

Which of the following statements is correct regarding ATP?

A

The energy in an ATP molecule is released through hydrolysis of one of the phosphate groups.

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24
Q

If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously?

A

Energy input into the organism must be occurring to drive the decrease in entropy.

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25
Which of the following states the relevance of the first lay of thermodynamics to biology?
Energy can be freely transformed among different forms as long as the total energy is conserved.
26
Which of the following is true regarding metabolic pathways?
Metabolic pathways consist of a series of reactions, each catalyzed by a different enzyme.
27
An exergonic (spontaneous) reaction is a chemical reaction that _____________________.
Releases energy when proceeding in the forward direction.
28
Which of the following correctly states the relationship between anabolic and catabolic pathways?
Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways.
29
Which of the following statements about enzyme function is correct?
Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output.
30
Which of the following statements correctly describes cofactors and coenzymes?
Both are no protein enzyme helpers; but, most ERC factors are metal ions, and coenzymes are organic molecules that are a specific type of cofactor.
31
A reaction that occurs spontaneously without an input of energy is ______________________.
Exergonic
32
A reaction that occurs non spontaneously-it requires an input of energy-is ________________________.
Endergonic
33
Exergonic reactions result in products that have less free energy than the reactants, thus free energy is released an DELTA G is ______________________.
Negative
34
Endergonic reactions result in products that have more free energy than the reactants, thus free energy is absorbed and DELTA G is __________________.
Positive
35
A cell can only carry out an _____________________ reaction by pairing it with an ______________________ reaction such as ATP hydrolysis.
Endergonic; Exergonic
36
How does the phosphorylation of glutamic acid (Glu) provide energy for the rest of the reaction to occur?
The addition of a phosphate to GLU forms a phosphorylated intermediate with more free energy than GLU. The ammonia can thus displace the phosphate in an exergonic reaction.
37
A chemical reaction occurs between the amino acids alanine (ALA) and glycine (GLY) forming the compound alanylglycine. The simple conversion reaction of alanine and glycine into this compound is endergonic, with a DELTA G of 6.9 kcal/mol. Therefore, it requires ATP hydrolysis to drove the non spontaneous reaction. Calculate the free energy change for the whole process, applying what you know about ATP hydrolysis.
DELTA G = -0.4 kcal/mol
38
The molecule that an enzyme reacts with is called the ____________________.
Substrate
39
Environmental conditions such as ___________________ and ______________________ can affect enzyme function.
Temperature; pH
40
Because an enzyme speeds up a chemical reaction, its called a _______________________.
Catalyst
41
A change in an enzyme’s structure that results in it not being able to perform its function is called ______________________.
Denaturation
42
An enzyme’s substrate fits into the ___________________ on the enzyme.
Active site
43
At which pH did pepsin function the best? In other words, at which pH were the most amino acids produced after 20 min?
Pepsin functions best at pH2
44
At which pH did trypsin function the best?
Trypsin functioned best at pH7
45
Based on the observations that pepsin’s optimal pH is 2 and trypsin’s optimal pH is 7, what can you conclude about the environment in which these two enzymes function in the body?
Pepsin’s environment in the stomach is very acidic, and trypsin’s environment in the small intestines has a neutral pH.
46
What is the ideal temperature for amylase function?
Amylase functioned best at 37 degrees C
47
What is the ideal temperature for Taq polymerase function?
Taq polymerase functioned best at 75 degrees C
48
What is happening at the molecular level that explains why enzymes function differently at different temperatures?
At the ideal temperature, the enzymes and substrate molecules will interact, enervating product molecules as quickly as possible. At a temperature that is too high, the enzymes will become denatured and lose the ability to react with their substrates. At a temperature that is too low, the enzymes and substrate molecules wont collide as often since they are moving more slowly.
49
What happens to the amount of disaccharides produced as you increase the initial amount of starch and why?
The amount of product increased as the initial starch increased. They enzyme continued to break down the starch.
50
Chemical equilibrium is reached when ________________________________.
The forward and reverse reactions occur at the same rate.
51
Which of the following is the strongest evidence that protein structures and functions are correlated?
Denatured (unfolded) proteins do not function properly.
52
Conservation of energy refers to the fact that ___________________.
energy cannot be created or destroyed but can be converted from one form to another.
53
Chemical energy is a form of ___________________ energy.
Potential
54
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?
Cellular respiration
55
What are byproducts of cellular respiration?
Heat, carbon dioxide, and water
56
The process of cellular respiration, which converts simple sugars such as glucose into CO2 and water is an example of __________________.
A catabolic pathway
57
What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?
Hydrolysis
58
The following reaction A—->B+C+heat is a(n) ____________________ reaction.
Exergonic
59
A(n) ______________________ reaction occurs spontaneously.
Exergonic
60
What reaction requires a net input of energy from its surroundings?
Endergonic
61
In cells, what is usually the immediate source of energy for an endergonic reaction?
ATP
62
The reaction ADP+P—>ATP is a(n) _________________ reaction
Endergonic
63
The energy for an endergonic reaction comes from a(n) _________________ reaction.
Exergonic
64
What is the fate of the phosphate group that is removed when ATP is converted to ADP?
It is acquired by a reactant in an endergonic reaction
65
What is energy coupling?
A description of energy released from an exergonic reaction to drive an endergonic reaction.
66
Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions?
Y-Phosphate (the terminal phosphate)
67
In general, enzymes are what kind of molecules?
Proteins
68
Enzymes work by _____________________.
Reducing Ea
69
An enzyme _____________________.
Is an organic catalyst
70
What name is given to the reactants in an enzymatically catalyzed reaction?
Substrate
71
As a result of its involvement in a reaction, an enzyme __________________.
Is uncharged
72
Enzymes are described as catalysts, which means that they _______________________.
Increase the rate of a reaction without being consumed by the reaction.
73
The binding of a compound to an enzyme is a served to slow down or stop the rate of the reaction catalyzed by the enzyme. Increasing the substrate concentration reduces the inhibitory effects of this compound. Which of the following could account for this observation?
The compound is a competitive inhibitor.
74
Which of the following is a characteristic feature of anabolic pathways?
They consume energy to build up polymers from monomers
75
Which of the following types of reactions would decrease the entropy within a cell?
Anabolic reactions
76
Select the correct statement about chemical energy, a term used by biologists to refer to potential energy available for release in a chemical reaction.
Light energy is converted to chemical energy during photosynthesis
77
The process of cellular respiration, which converts simple sugars such as glucose into CO2 and water is an example of _______________________.
A catabolic pathway
78
Catabolism is to anabolism as ________________ is to __________________.
Exergonic; endergonic
79
The mathematical expression for the change in free energy of a system is DELTA G = DELTA H - T DELTA S. Which of the following statements best describes a term in this equation?
DELTA G is the change in energy
80
Which of the following statements best describes an exergonic reaction?
The reaction proceeds with a net release of free energy
81
Which of the following terms best describes a chemical reaction for which DELTA G is positive?
Endergonic
82
Which of the following statement best describes a system at chemical equilibrium?
The system can do no work
83
The relationship between the breakdown of macromolecules and the biosynthesis of macromolecules is most similar to the relationship between which of the following pairs of terms?
Exergonic and endergonic
84
Which of the following statements best describes why hydrolysis reactions occur more readily in solution than dehydration reactions do?
Hydrolysis reactions are exergonic and increase entropy of the system
85
Which of the following metabolic processes can occur without a net influx of energy from some other process?
C6H12O6+6O2+6H2O
86
Which of the following statements best describes the central role that ATP plays in cellular metabolism?
ATP provides energy coupling between exergonic and endergonic reactions.
87
Which of the following statements best describes catabolic path ways?
They are exergonic and provide energy that can be used to produce ATP from ADP and Pi
88
When chemical, transport, or mechanical work is performed by an organism, what happens to the heat that is generated?
It is lost to the environment
89
The DELTA G of ATP hydrolysis in a test tube under standard conditions is -7.3kcal/mol. The DELTA G for the reaction A+B=C under the same conditions is +4.0 kcal/mol. What is the over all free-energy for the coupled reaction under these conditions?
-3.3 kcal/mol
90
If an enzyme in solution is saturated with substrate, the more effective way to obtain a faster yield of products is to _____________________.
Add more of the enzyme.
91
Some bacterial are metabolically active in hot springs because
Their enzymes have high optimal temperatures.
92
Which of the following statements best describes enzyme function?
Enzymes increase the rate of chemical reactions by lowering activation energy barriers.
93
A clasping handshake may be used as an analogy for an enzyme-catalyzed reaction because it represents the specific manner in which an enzyme _______________________.
Binds substrate
94
What is the name of the barrier that must be overcome before products are formed in a spontaneous reaction?
Activation energy
95
Which of the following statements best describes induced fit?
Binding of substrate to the activation site changes the shape of the active site of an enzyme.
96
How does a non competitive inhibitor decrease the rate of an enzyme-catalyzed reaction?
By binding to an almost Eric site, thus changing the shape of the active site of the enzyme.
97
Which of the following statements best describes how addition of a catalyst will affect a chemical reaction?
Th3e catalyzed reaction will have the same DELTA G as the un-catalysed reaction
98
An enzyme-catalyzed reaction has a DELTA G of -20 kcal/mol under standard conditions. What will be the DELTA G for the reaction if the amount of enzyme is doubled?
-20kcal/mol
99
Disruption of the active site of an enzyme would most likely result in which of the following?
A decreased ability of the enzyme to bond substrates
100
In the citric acid cycle, succinct dehydration catalyzes the conversion of succinct to fumarate. This reaction is inhibited by malonate, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Which of the following statements best describes the role played by molecules described in the reaction?
Succinate dehydrogenase is the enzyme, and malonate is the substrate in the reaction.

Cellular Biology 201 UNCW (11 decks)

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