Chapter 6 Flashcards
1
Q
Metabolism
A
the sum of all chemical reactions taking place in a living cell
2
Q
Products of cellular respiration are almost always
A
CO2+ Water
3
Q
Catabolic Pathways is a _________ process
A
degradative
4
Q
Anabolic Pathways is a _______ process
A
synthesis process
5
Q
In catabolic pathways energy is
A
released
6
Q
In anabolic pathways energy is
A
absorbed
7
Q
In catabolic pathways bonds are
A
broken
ex: cellular respiration
8
Q
In anabolic pathways bonds are
A
formed
9
Q
True or False: Anabolic pathways usually involve hydrolysis reactions, while catabolic pathways typically include dehydration reactions
A
false: anabolic pathways usually involve dehydration reactions, while catabolic pathways typically include hydrolysis reactions
10
Q
Energy
A
the capacity to cause change, some forms can be used to do work
11
Q
Kinetic Energy
A
energy of motion
ex: thermal heat, light energy
12
Q
Potential Energy
A
energy that is stored
ex: chemical bonds
13
Q
Thermodynamics
A
study of energy transformations
14
Q
Closed System
A
a system that is isolated from surroundings
15
Q
Isolated vessel closed to the environment
-does not allow for exchange of matter or energy between the environment and the system
-eventually equilibrium will be reached
A
Example of a closed system
16
Q
Open System
A
a system that exchanges matter and energy with surroundings
17
Q
Cells and the ecosystem allows for exchange of matter and energy between the environment and the system
A
Example of an open system
18
Q
Are living things considered to be open systems or closed systems?
A
open systems
19
Q
1st Law of Thermodynamics: Principle of Conservation of Energy
A
the energy of the universe is constant. It can be transferred/transformed, but it cannot be created or destroyed
20
Q
Example of the 1st Law of Thermodynamics
A
consumption of food
chemical energy in food becomes kinetic energy for us
21
Q
2nd Law of Thermodynamics: Natural processes tend to move forward toward the state of greater disorder
A
natural processes tend to move toward the state of greater disorder or randomness
22
Q
Example of the 2nd Law of Thermodynamics
A
movement increases disorder around the body by the release of heat and by-products of metabolism
23
Q
Gravitational Motion
A
objects move spontaneously from a higher altitude to a lower one
24
Q
Diffusion
A
molecules in a drop of dye diffuse until they are randomly dispersed
25
Chemical Reaction
in a cell, a sugar molecule is broken down into simpler molecules
26
Gibbs Free Energy
amount of energy available for work when temperature is uniform throughout the system
27
In a spontaneous change
the free energy of the system decreases
the system becomes more stable
the released free energy can be harnessed to do work
28
_____ free energy means ____ stable which means _______ work capacity
more free energy means less stable which means greater work capacity
29
____ free energy means ____ stable which means ____ work capacity
less free energy means more stable which means less work capacity
30
True or False: in an isolated system, spontaneous reactions increase entropy
true
31
Is energy required for exergonic "downhill" reactions?
no
32
Is energy required for endergonic "uphill" reactions?
yes
33
Are exergonic reactions spontaneous?
yes
34
Are endergonic reactions spontaneous?
no
35
Is free energy released or added in exergonic reactions?
released
36
Is free energy released or added in endergonic reactions?
added
37
Is the free energy change positive or negative in exergonic reactions?
negative free energy change
38
Is the free energy change positive or negative in endergonic reactions?
positive free energy change
39
Are exergonic reactions catabolic or anabolic?
catabolic
40
Are endergonic reactions catabolic or anabolic?
anabolic
41
Energy Coupling
occurs when energy produced from an exergonic reaction is used to drive an endergonic reaction
42
True or False: Sodium Potassium pumps use the energy derived from exergonic ATP hydrolysis to pump sodium and potassium ions across the cell membrane
true
43
The structure of ATP is similar to the structure of a
RNA molecule
44
ATP structure has how many phosphate groups?
3
45
The bonds in ATP are relatively unstable due to the negative charges of the
phosphate groups
46
Name each group present in this image
Triphosphate group
Ribose
Adenine
47
What are the three types of cellular work driven by the hydrolysis of ATP
chemical work
mechanical work
transport work
48
Chemical Work
reaction that requires energy coupling
49
Mechanical Work
membrane protein changes shape and actively transports solute
50
Transport Work
motor protein changes shape and moves with vesicle
51
Chemical Work
52
Mechanical Work
53
Transport Work
54
Metabolic reactions require catalysts which ________ the rate of a reaction
increase
55
Catalysts provide an energy boost to reactions by lowering the Ea aka
activation energy
56
Enzymes are proteins that bind to a specific
substrate
57
Specificity is determined by
enzyme's conformation
58
Active Site
region of enzyme that binds to substrate
59
Induced Fit
substrate binding induces a change in the active site of the enzyme, leading to a tight binding of the substrate
60
True or False: the enzyme is consumed and degraded during the reaction
false
61
Steps of Enzyme- Substrate Interaction
1. substrate enters active site
2. substrates are held in active site by strong interactions such as hydrogen and ionic bonds
3. active site can speed up the reactions by lowering Ea
4. substrates are converted to products
5. products are released
6. active site is available for new substrate molecules
62
What affects enzyme activity?
1. temperature
2. pH
3. relative connections of enzyme and substrate
4. presence of inhibitors and/or activators
63
True or False: as seen in the example to the right, bacteria living in a hot spring have enzymes that can perform best at 24 degrees celcius?
true
64
Normal Binding
substrate binds to active site
65
Types of Inhibition
irreversible inhibition
competitive inhibition
noncompetitive inhibition
66
Irreversible Inhibition
inhibitor binds active site and forms strong covalent bonds
67
Competitive Inhibition
inhibitor mimics shape of substrate and competes with substrate for binding to active site
68
Noncompetitive Inhibition
inhibitor binds to enzyme away from the active site altering the shape of the active site
69
True or False: Non-competitive inhibitors can be out competed by increased substrate
false
70
A series of reactions can be called a
metabolic pathway
71
A common mode of control for metabolic pathways catalyzed by enzymes is called
feedback inhibition
72
The inhibitor is typically the final product of
the biochemical pathway
73
True or False: feedback inhibition prevents the cell from making more products than is necessary, and thus wasting resources
true
74
Enzymes can be regulated allosterically when they have a _________________ level of protein structure
quaternary structure
75
Allosteric activators stabilize the ______ form
active
76
Allosteric inhibitors stabilize the
inactive form
77
Homotropic Regulation
specialized kind of allosteric activation, where the substrate acts as the activator
78
when we build new biological molecules from pieces, we have to fuse those pieces together with energy
when we break molecules down into their components, the energy stored in the bonds is released
metabolism
79
the energy needed to start a chemical reaction is called
Activation Energy
80
Enzymes DON'T
Enzymes DO
they don't add energy to reactions
they do speed up reactions by lowering the energy barrier
81
Induced Fit
active site changes shape even more to fit the substrate better
82
Active site enzymes can either _______ or _________ the substrate; resulting in a _______
active site enzymes can either build up or breakdown the substrate; resulting in a product
83
With the enzyme, lactase, _______ can be broken down faster
lactose
84
Those who are lactose intolerant can't produce enough _______ to breakdown lactose
lactase
85
Digestive System Enzymes
lipase
amylase
protease
86
Lipase breaks down
lipids
87
Amylase breaks down
starch/carbohydrates
88
Protease breaks down
proteins
89
Cofactors
typically metal ions such as iron that help the enzyme buildup or breakdown substrates into products
90
Coenzymes
organic molecules like vitamins that help the enzyme build up or breakdown substrates into products
91
If the environment changes out of an enzyme's ideal pH or temp range, enzyme becomes
denatured; shape becomes distorted so it can no longer bind to the substrate
92
Pepsin and trypsin
enzymes that breakdown proteins; action location for pepsin is the stomach and small intestine for trypsin
93
Pepsin and trypsin break down
peptide bonds in proteins
pepsin breaks down proteins into peptides
94
Nucleases
break down phosphodiester bonds and helps them break into nucleotides
95
Enzyme substrate complex
when the substrate is bonded to the active site
96
True or False: cofactors and coenzymes may be permanent or temporary which often depend on how they're bonded
true
97
DNA polymerase has ____ ion as a cofactor
zinc
98
When a ______________ inhibitor binds to an allosteric site, the enzyme has a shape change. After this change, the enzyme might not work well enough or at all
non-competitive
99
ACE inhibitors work on
high blood pressure by blocking angiotensin-converting enzymes
when inhibited, enzymes can't convert angiotensin to angiotensin II
100
Angiotensin II is involved with
raising blood pressyre
101
Penicillin is an antibiotic, but it works by inhibiting the enzyme ______________ that prevents many types of bacteria from being able to build a cell wall
transpeptidase
102
Some bacteria are metabolically active in hot springs because __________.
their enzymes have high optimal temperatures
103
What is true about the active site of an enzyme?
The active site may resemble a groove or pocket in the surface of a protein into which the substrate fits.
104
What is a correct statement about the relationship between anabolic and catabolic pathways?
Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways.
105
What is the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________
exergoinc; endergonic
106
What is a correct statement about enzyme function?
Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output.
107
What is changed in a reaction by the action of an enzyme?
the activation energy
108
What is an example of an endergonic reaction?
glucose + fructose= sucrose
109
What determines the sign of delta G for a reaction?
The free energy of the reactants and the free energy of the products
110
The binding of an allosteric inhibitor to an enzyme causes the rate of product formation by the enzyme to decrease. What best explains why this decrease occurs?
the allosteric inhibitor causes a structural change in the enzyme that prevents the substrate from binding at the active site
111
If the entropy of a living organism is decreasing, what is also occurring?
energy is being supplied to the organism
112
In general, the hydrolysis of ATP drives cellular work by __________.
releasing free energy that can be coupled to other reactions
113
Metabolic pathways in cells are typically far from equilibrium. Which processes tends to keep these pathways away from equilibrium?
The continuous removal of the products of a pathway to be used in other reactions and the input of free energy from outside the pathway
114
A chemical reaction is designated as exergonic rather than endergonic when __________.
the potential energy of the products is less than the potential energy of the reactants
115
The formation of glucose-6-phosphate from glucose is an endergonic reaction and would, therefore, be coupled to which of the following reactions or pathways?
The hydrolysis of ATP
116
Which of the following metabolic processes can occur without a net influx of energy from some other process?
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
117
What do the sign and magnitude of the ΔG of a reaction tell us about the speed of the reaction?
Neither the sign nor the magnitude of ΔG has anything to do with the speed of a reaction.
118
What is a true statement about enzyme inhibitors?
The action of competitive inhibitors may be reversible or irreversible.
119
Enzyme activity is affected by pH because __________.
high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the enzyme’s active site
120
What statement best characterizes the functional role of ATP in cellular metabolism?
The free energy released by ATP hydrolysis is coupled to endergonic processes via the formation of a phosphorylated intermediate.
121
Much of the suitability of ATP as an energy intermediary is related to the instability of the bonds between the phosphate groups. These bonds are unstable because __________.
the negatively charged phosphate groups vigorously repel one another and the terminal phosphate group is more stable in water than it is in ATP
122
The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of __________.
allosteric regulation
123
Most cells cannot harness heat to perform work because __________.
temperature is usually uniform throughout a cell
124
You have added an irreversible inhibitor to a sample of enzyme and substrate. At this point, the reaction has stopped completely.
What can you do to regain the activity of the enzyme?
The enzyme is inactive at this point. New enzyme must be added to regain enzyme activity.
125
You have an enzymatic reaction proceeding at the optimum pH and optimum temperature. You add a competitive inhibitor to the reaction and notice that the reaction slows down.
What can you do to speed the reaction up again?
Add more substrate; it will outcompete the inhibitor and increase the reaction rate.
126
There are three main types of cellular work: chemical, transport, and movement. Most of this work is powered by the transfer of a phosphate group from one molecule to another in a process known as
phosphorylation
127
Through energy coupling, cells use _______, or energy releasing, reactions to drive _______, or energy-requiring, reactions. The molecule ___ is the energy shuttle between these two types of reactions
exergonic
endergonic
ATP
128
Mechanisms such as ________________ enable precise control over a cell's __________ all of it's chemical reactions
feedback inhibition
metabolism
129
Consider a situation in which the enzyme is operating at optimum temperature and pH
, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?
increase the enzyme concentration
130
In general, enzymes are what kinds of molecules?
proteins
131
Enzymes work by
reducing Ea
132
An enzyme
is an organic catalyst
133
Three true statements about enzymes
reactants cannot convert to products without an initial input of energy to start the reaction
enzymes lower the overall energy input needed for a reaction to occur
by binding to reactant molecules, enzymes make it easier for the bonds in the molecules to break apart
