Chapter 6: Energy And Enzymes Flashcards
(164 cards)
1
Q
what are the types of energy in the cell?
A
chemical energy, ion gradients, and solar energy
2
Q
what molecules have chemical energy?
A
organic (ATP, NADH)
3
Q
what types of chemical energy are there?
A
ATP/GTP, NADH/FADH2, other high energy molecules
4
Q
what provided energy for enzyme reactions?
A
NADH/ FADH2
5
Q
What is ATP’s bonding?
A
high energy bonds between the P groups
6
Q
How does ATP energy work?
A
when the P-P bonds are broken the energy released can be used in enzyme reactions
7
Q
what does ATP hydrolysis produce?
A
ADP + P + energy
8
Q
what is redox reaction?
A
oxidation-reduction reaction
9
Q
which form normally has the H?
A
reduced
10
Q
in a redox reaction, where are the reduced and oxidized form?
A
both sides
11
Q
what is the reduced form?
A
High energy form
Has accepted a pair of electrons
12
Q
what is the oxidized form?
A
low energy form
has lost a pair of electrons
13
Q
reduced compounds transformation
A
loses electrons and become oxidized
14
Q
oxidized compounds transformation
A
gains electrons and becomes reduced
15
Q
when a compound gains an electron what else does it sometimes pick up?
A
H- it neutralizes the charge
16
Q
OILRIG
A
oxidation is loss of electrons
reduction is gain of electrons
17
Q
What is an ion gradient?
A
when the concentration of the ion is higher on one side of the membrane
18
Q
in an ion gradient, as ions flow across the membrane down their concentration gradient, energy is
A
released to move some other substance or make ATP
19
Q
what is solar energy?
A
energy from sunlight can be used for electron transport during photosynthesis
20
Q
what are the parts of photosynthesis?
A
light reactions, sunlight, electron transport =H+ gradient, ATP/NADPH =chemical energy
21
Q
what is thermal energy
A
heat
22
Q
what is chemical energy?
A
stored in the bonds of molecules
23
Q
what is the first law of thermodynamics?
A
energy cannot be created or destroyed- energy can be converted from one type of energy to another type of energy
24
Q
what law says energy can only change form?
A
1st
25
what is the 2nd law of thermodynamics?
any energy transformation increases the disorder of a system; entropy
26
what is entropy
A measure of disorder or randomness
27
reactions are a part of a
pathway
28
each reaction is catalyzed by a
enzyme
29
is all enzymes in a reaction needed?
yes- to get to the final product
30
what is the reactant?
sunbstrate
31
what is a substrate?
the starting compound in a reaction
32
what is the product?
compound made at the end of a reaction
33
-ace is normally a
enzyme
34
what is a chemical equilibrium?
when the rate of formation of products equals the rate of formation of reactants
35
chemical reactions will reach a
equilibrium
36
Keq>1 means
the formation of products is favored
the reaction is mainly going left to right
37
what is the equation for Keq?
(C)c(D)d
————
(A)a(B)b
38
what does a larger Keq mean?
the more of a product is made relative to reactant at equilibrium
39
the more products you get is by
A bigger Keq
40
what is free energy?
The energy that can be used to do work
41
what way do reactions tend to proceed in?
the direction that causes a decrease in the free energy of the system (^G=negative)
42
what are exergonic reactions?
where energy is released and ^G is negative
43
what reactions are spontaneous?
exergonic
44
what are endergonic reactions?
are reactions where energy must be input in order to occur (^G is positive
45
what is the name of more than one reaction occurring at the same time?
coupled
46
when will couples reactions not go?
when the overall ^G is positive
47
when will a coupled reaction go?
when the overall ^G is negative
48
exergonics energy is coming _
endergonic energy is coming _
out
in
49
what are coupled reactions?
spontaneous or not?
spontaneous
50
what are catalysts?
increase the rate of reaction
51
what are not used up in the reaction?
catalysts (they are reusable)
52
Catalysts _ reactant
don’t equal
53
do catalysts alter the equilibrium of a reaction?
no
54
what decreases the amount of time required to reach equilibrium?
catalyst
55
what are the special features of enzymes?
specific, efficient, and regulated
56
what is specific?
enzymes perform one reaction or type of reaction
57
Kinase adds a phosphate group to a certain enzyme or protein. It won’t add a group to every single enzyme or protein so which feature is it?
specific
58
what is efficient?
enzymes increase the rate of reaction dramatically
59
what is regulated?
enzymes can be turned on and off
60
why are enzymes regulated?
they take a long time to build so you don’t want rebuild each time so you turn on and off
61
enzymes work in
pathways
62
what is interconnected
pathways
63
flow through a pathway can be
regulated
64
catabolic is
Anabolic is
breakdown
synthesis
65
what state do substrates go though?
activated transition state
66
what is a transition state?
intermediate whose free energy is higher that that of the reactants
67
formula for transition state
enzyme+ substrate -> enzyme-substrate complex -> enzyme + product
68
are substrate and molecules stable during transition state?
yes
69
what is activation energy?
the amount of energy that must be added for a reaction to proceed
70
how do enzymes speed up a reaction?
they lower the activation energy of a reaction
71
what type of energy could be activation?
heat or kinetic energy
72
enzymes catalyzed reactions go through a ____ whose free energy is ____ than the intermediate if the _______
transition state
lower
uncatalyzed reaction
73
how do enzymes lower the activation energy?
enzymes can interact with the substrate and provide an alternate transition state
74
what is an alternate transition state?
different intermediate
75
what is Ea
activation energy
76
what do enzymes do for the reaction to occur?
hold the substrates in the proper orientation
77
what is enzyme specificity determined by?
the shape of the active site
78
what is an active site?
location in the enzyme where reactions take place and where substrates have to bond to
79
what is the lock and key model?
only the right substrate (key) will fit in the active site (keyhole) of the enzyme (lock)
80
when are molecules substrates?
only when molecules can fit into the active site of an enzyme are substrates for the reaction
81
why are substrates oriented?
so the bond to be cleaved is in a certain position
82
what is a variation of the lock and key model?
induced fit model
83
anytime something bonds, what happens to the activity?
it can become more or less active and it will change its shape
84
what is the induced fit model?
when substrates bind to enzyme the shape of the enzyme changes slightly to improve catalytic activity of the enzyme
85
what does the lock and key model help enzymes be?
very efficient
86
how are substrates held?
in close proximity and proper orientation
87
what do active sites contain?
functional groups that temporarily donate H+s or e-s
88
what happens during binding of substrate to enzyme?
it induces strain on the substrate molecule and makes it more reactive
89
what is covalent intermediates?
has a slightly higher energy level and are temporary
90
catalytic efficiency is the formation of
covalent intermediates
91
list the steps of catalytic reaction
the active site lowers the activation energy
acts as a template for the reaction
stresses the substrate
stabilizes the transition state
participates in catalytic reaction
92
what is more likely when a intermediate is stabilized?
it is more likely to go through
93
how do enzymes compare to themselves in the beginning of a reaction
they look exactly the same
94
what does a small change in ph do? (<1 ph unit)
change the charge on the substrate
change the charge on the enzyme (active site)
the substrate may no longer be able to bind to enzyme or not bind as well so the enzyme will be less active
95
what is a proteins shape essential for?
its function
96
what is a denatured protein?
it loses its 3d shape and becomes an unfolded chain of amino acids
it will not function properly
97
what happens during denaturing?
the ionic, H bonds, and disulfide bonds that hold the protein in its 3d shape are broken and the enzymes unfolds
98
what is the formation of amino acids while denatured?
still connected in a chain by peptide bonds
99
What causes protein denaturation?
large change in ph
acidic
basic
high temps
100
Is denaturing temporary or permanent?
permanent
101
What happens when an enzyme reaches past its optimal temp or ph?
denaturation
102
are some enzymes more sensitive to ph than others?
yes
103
what is ph optimum
the ph at which the enzyme performs the reaction at the maximum rate
104
when does an enzyme become denatured with the ph optimum?
when it is above or below it- it becomes less active
105
How is an enzymes ph optimum chosen?
depends on where they work
106
what ph optimum do most enzymes have?
one that matches the ph of the environment the enzyme is designed to work for
107
what happens with a large change in ph (>1 ph unit)
breaks ionic and H bonds that hold protein in its 3d shape
enzymes may partially unfold and become less active
Enzyme may completely unfold (denature) and become totally inactive
108
a relative change in ph will ____ and as it goes farther it will ____
slightly unfold
more unfolded and it will unravel
109
what is the stomach enzyme?
what is it ph optimum?
pepsin
2
110
what is the intestinal enzyme?
what is the ph optimum?
trypsin
8
111
what is the ph optimum of most enzymes? why?
7 because most ph of cells is 7
112
what do most enzymes have a temp optimum of?
equal to the body temp of the organism they are from
113
what does a high temp do?
breaks ionic and h bonds that holds the enzyme into its 3d shape
114
what is the human enzymes temp?
37c
115
what happens with cold temps?
the exams will not be denatured. It is less active because molecules have less kinetic energy at low temps
116
what to do if you want to preserve enzymes?
put it on ice-cold
117
what is kinetic energy?
energy associated with movement
118
How does kinetic energy affect the reaction rate?
more kinetics energy, more collisions between molecules, faster reaction rate
119
how does cold temps affect kinetic energy?
the colder the temp, the less kinetic energy a molecule has, so there will be feeer collisions between molecules, lower and slower reaction rate
120
___ temp= ___ kinetic energy = ____ reaction rate
low, low, low
121
what are the factors for maximal enzyme activity?
prosthetic group
coenzymes
cofactors
122
what is a prosthetic group?
small organic molecule permanently (covalently) bound to enzyme; Heme
123
what are coenzymes?
small organic molecule (volume derivatives) bind temporarily (ionic or h bonds) to enzyme
124
what does a coenzyme need for?
to function right
125
what are cofactors?
metal ions: fe, Mg
126
what is required for proper 3d shape of protein and active site?
prosthetic group
coenzyme
127
what is directly involved in chemical reaction?
cofactor and coenzymes
128
what may change the shape of the active site?
coenzymes
129
what makes temporary bond between 2 substrates?
coenzymes
130
what is an inhibitor?
molecule or ion that binds to enzyme and decreases its activity
131
what happens when an inhibitor is present?
it changes the shape so the substrate can’t bind to it, it makes it less active or completely
132
how can an inhibitor bind to the active site?
what type?
It must resemble the substrate
competitive
133
if the competitive inhibitor binds to the active site, the substrate ___ so ___ reaction
can’t
no
134
a competitive inhibitor is called this because
they are both competing for the active site
135
the more inhibitor is added the ____ reaction is inhibited
more
136
how many enzyme molecules are in a cell?
100s or thousands
137
the more inhibitor binds to the active to ___ the reaction rate
lower
138
what are noncompetitive inhibitors?
binds to enzyme noncovalently at the allosteric site- won’t bind to the active site
139
do some proteins have more than one subunit?
yes
140
what is the catalytic subunit?
contains the active site and performs the reaction
141
what are regulatory sununits?
contains the allosteric site and regulates enzyme sctivity
142
noncompetitive inhibitors bind to ___ on ___ subunits
allosteric
regulatory
143
what does noncompetitive inhibitors change shape of?
regulatory and catalytic subunits
144
control of enzyme activity is
allosteric regulation and noncompetitive inhibitors
145
how many subunits do allosteric enzymes have?
more than one
146
what is a catalytic subunit?
binds substrate at the active site, performs enzyme reaction
147
what is a regulatory subunit?
binds an effector at the allosteric site, controls activity of the enzymes
148
what are effectors and where do they bind to?
small organic molecule that controls the activity of the enzyme and bind to the allosteric site
149
what two things can effectors be?
inhibitors or activators
150
what two forms do allosteric enzymes have?
active- form of the enzyme that performs its function (on)
inactive - nonfunctional form of enzyme (off)
151
what do effectors control?
Activity of enzyme
152
what do regulatory molecules/effectors bond to?
regulatory subunit and causes it to change shape
153
what does a change in shape of the regulatory subunit cause?
catalytic subunit to change shape- turns it in inactive form, off
154
what may regulatory subunits bound to?
catalytic subunits but they both change shape
it can either be bound or released but either way it will change shape
155
What is allosteric inhibition?
an inhibitor (effector) binds to the regulatory subunit which causes the subunit to change shape.
156
change of shape of regulatory subunit cause catalytic subunit to change ____
shape from active form to inactive form
157
what is feedback inhibition?
accumulation of the product of a metabolic pathway inhibits one of the enzymes at the beginning of the pathway
158
what is feedback inhibition a kind of?
allosteric inhibition
159
process of feedback inhibition
Inhibitor binds to allosteric site on regulatory subunit of enzyme 1, regulatory subunit changes shape, catalytic subunit changes shape (inactive form)
160
when a product made at the end of a pathway binds to one of the enzymes near the beginning of pathway and inactivates the enzyme
feedback inhibition
161
allosteric regulation is a kind of
noncompetitive inhibition
162
what is allosteric regulation used for?
regulate enzymes in pathway
163
what is an allosteric inhibitor?
chemical binding of the effects makes enzyme less active
active enzyme-> inactive off
164
what is an allosteric activator?
chemical binding of the effects makes enzyme more active
inactive enzyme -> active, on
