Metabolism and ATP Flashcards
(215 cards)
1
Q
An organism’s metabolism transforms
A
matter and energy,
2
Q
An organism’s metabolism is
subject to
A
the laws of thermodynamics
3
Q
The free-energy change of a reaction tells us
A
whether or not the reaction occurs spontaneously
4
Q
ATP powers cellular work by
A
coupling exergonic reactions to endergonic reactions
5
Q
Enzymes speed up metabolic reactions by
A
lowering energy
barriers
6
Q
Regulation of enzyme activity helps
A
control metabolism
7
Q
A living cell is a
A
miniature chemical factory where
thousands of reactions occur
8
Q
The cell extracts energy
A
stored in sugars and other
energy-containing organic molecules
9
Q
The cell extracts energy and applies
A
energy to perform work
10
Q
Metabolism
A
the totality of an organism’s chemical
reactions
11
Q
metabolism is an _______ from _____
A
emergent property and interactions between molecules in cell
12
Q
Metabolic pathways
A
begin with a specific molecule
(substrate or reactant) and end with a product
13
Q
Each step in the metabolic pathways us
A
catalyzed by a specific enzyme
14
Q
Catabolic pathways
A
release energy by breaking down
complex molecules into simpler compounds
15
Q
example of catabolic pathways
A
Cellular respiration
16
Q
how is Cellular respiration an example of a catabolic pathway
A
breakdown of glucose in the
presence of oxygen
17
Q
Anabolic pathways
A
consume energy to build complex
molecules from simpler ones
18
Q
Anabolic pathway example
A
Synthesis of protein from amino acids
19
Q
Bioenergetics
A
the study of how organisms manage
their energy resources
20
Q
Energy
A
the capacity to cause change
21
Q
Energy exists in ______ and some can _____
A
various forms and perform
work
22
Q
Energy can be converted
A
from one form to another
23
Q
Kinetic energy
A
energy associated with motion
24
Q
thermal energy is also known as
A
heat
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Heat (thermal energy)
kinetic energy associated with
random movement of atoms or molecules
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Potential energy
energy that matter possesses
because of its location or structure
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Chemical energy
potential energy available for release
in a chemical reaction
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Thermodynamics
the study of energy transformations
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two types of systems
1. open system
2. isolated system
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isolated system
unable to exchange energy or
matter with its surroundings
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open system
energy and matter can be transferred
between the system and its surroundings
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organisms are _____ systems
open
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first law of thermodynamics
the amount of
energy in the universe is constant
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how is the amount of
energy in the universe is constant
Energy can be transferred and transformed, but it cannot be
created or destroyed
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what is first law of thermodynamics also known as
principle of conservation of energy
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During every energy transfer or transformation, some energy is
unusable, and often lost as heat
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The second law of thermodynamics
Every energy transfer or transformation increases
entropy (disorder) of the universe
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Living cells convert what to what
organized forms of energy to heat
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Spontaneous processes
without energy input
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For a process to occur without energy input
it must increase entropy of universe
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Spontaneous processes can happen
quickly or slowly
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Cells create ordered structures from
less ordered materials
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Cells create ordered structures from less ordered materials
Requires the input of energy
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Organisms also replace
ordered forms of matter and
energy with less ordered forms
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* Energy flows into an ecosystem in _____ and exits in ____
form of light
form of heat
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Evolution of more complex organisms
does not violate
the second law of thermodynamics
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Entropy (disorder) may _____ in an organism, but universe’s total entropy ____
decrease and increases
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Biologists want to know
which reactions occur
spontaneously and which require input of energy
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An unstable system is
rich in free energy.
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An unstable system has a tendency to
change spontaneously to a more stable state
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how does the free-energy concept apply on a molecular scale
to the physical movement of molecules
known as diffusion
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less free energy means what (2)
1. more stable
2. less work capacity
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Chemical reactions also involve
free energy.
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When catabolic pathways break down complex organic molecules what can a cell do
harness the free energy stored in the molecules to perform
work
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Free energy
-It is the amount of energy that is available to do work.
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what is a criterion for spontaneous change
Free energy
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G
Free energy
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Free energy is related to the systems
total energy and entropy
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H
enthalpy of total energy
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S
entropy
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T
Temperature in K
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Free Energy equation
G = H-TS
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Free energy (g) is proportional to the
system's energy available to do work
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free energy is the difference between
the total energy (enthalpy) and
the energy not available for doing work (TS)
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The maximum amount of usable energy that can be harvested from a particular reaction is
the system’s free energy change from the
initial to the final state.
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Gibbs-Helmholtz equation
change in free energy (ΔG) at a constant Temp and pressure
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ΔG
change in free energy
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ΔH
change in total energy
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the total energy is also known as
enthalpy
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ΔS
change in entropy
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T
absolute temp in K
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how to calculate Kalvins
(Degree Celius + 273)
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ΔG equation
ΔG = ΔH – TΔS
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The living system’s free energy is
the energy that can do work
when temperature and pressure are uniforms,
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spontaneous processes have a
negative ∆G
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what can spontaneous processes be harnessed to do
perform work
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During a spontaneous change, free energy ____ and the stability of a system ____
decreases and increases
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* Free energy is a measure of a
system’s instability
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system’s instability
tendency to change to a more stable state
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Equilibrium is a state
of maximum stability
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A process is spontaneous and can perform work only
when it is moving toward equilibrium
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more free energy =
1. higher G
2. less stable
3. greater work capacity
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In a spontaneous change
1. free energy of the system decreases
2. system becomes more stable
3. released free energy can be used to do work
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the final result of the change
1. less free energy
2. lower G
3. more stable
4. less work capacity
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Based on their free energy changes, all chemical reactions
classified as exergonic or endergonic
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relationship between chemical equilibrium and the free energy change (ΔG) of a reaction
1. As a reaction approaches equilibrium, the free energy of the system decreases
2. When a reaction is pushed away from equilibrium, the free energy of the system increases
3. When a reaction reaches equilibrium, ΔG = 0
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When a reaction reaches equilibrium, ΔG = 0
no net change in the system
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When a reaction is pushed away from equilibrium, the free energy of the system increases
non-spontaneous and
endergonic reaction
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As a reaction approaches equilibrium, the free energy of the system decreases
spontaneous and exergonic reaction
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Reactions can be classified based on their free energy changes
Exergonic reaction
Endergonic reaction
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Exergonic reaction
a reaction that proceeds with a net
loss of free energy.
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Endergonic reaction
an energy-requiring reaction that
proceeds with a net gain of free energy;
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a reaction absorbs free energy from its surroundings
Endergonic reaction
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Chemical products have less free energy than the reactant molecules
Exergonic reaction
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Reaction is energetically downhill
Exergonic reaction
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Spontaneous reaction
Exergonic reaction
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ΔG is negative
Exergonic reaction
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ΔG is the maximum amount of work the reaction can perform
Exergonic reaction
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Products store freer energy than reactants
Endergonic reaction
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The reaction is energetically uphill
Endergonic reaction
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Non-spontaneous reaction
requires energy input
Endergonic reaction
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ΔG is positive.
Endergonic reaction
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+ΔG is the minimum amount of work required to drive the reaction
Endergonic reaction
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* An exergonic reaction proceeds
with a net release of free energy and is spontaneous
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* Exergonic reaction is
spontaneous
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Energy is released during
the progress of an exergonic reaction.
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The amount of energy released is delta G
less than zero
Exergonic reaction
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The exergonic reaction is the
difference between the ____ free energy of
the reactants and the ____ free energy of
the products
higher and the lower
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An endergonic reaction
absorbs free energy from its
surroundings and is nonspontaneous
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nonspontaneous
Endergonic reaction
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Energy is required during the progress
* Endergonic reaction
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The amount of energy required is delta G
greater than zero
* Endergonic reaction
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Endergonic reaction is the
difference between the ____ free energy
of the reactants and the ____ free energy
of the products
lower and higher
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Reactions in a closed system
eventually, reach equilibrium
and then do no work
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Cells are
not in equilibrium and open systems
experiencing a constant flow of energy and matter
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* Defining feature of life
is that metabolism is never at
equilibrium
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Catabolic pathway in a cell
releases free energy in a series
of reactions
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If a chemical process is exergonic the reverse process
must be endergonic
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For each mole of glucose oxidized in the exergonic process of cellular respiration
2870 kJ are released
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To produce a mole of glucose, the endergonic process of photosynthesis requires
energy input of 2870 kJ
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The individual steps of respiration in isolation would
come to equilibrium and the cellular work would cease
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in respiration, there is a series of drops in free energy between
glucose, the start material and the metabolic wastes at the end
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with the steps, respiration will
never reach equilibrium as long as the organism lives
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with multiple steps, the _____ becomes the _____ for the next and the _____ are expelled from the cell
1. product
2. waste
3. metabolic wasts
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three kinds of cellular work
1. chemical
2. transport
3. mechanical
126
To do work, cells manage energy resources by
energy coupling
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energy coupling
use of an exergonic process to drive an endergonic one
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Most energy coupling in cells is mediated by
ATP (adenosine triphosphate)
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cell’s energy shuttle
ATP
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ATP has what nitrogen base
adenine
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Bonds between the phosphate groups of A T P can be broken
by hydrolysis
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- Energy is released from ATP with
the terminal phosphate bond of ATP broken
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The release of energy comes from the ATP molecule is
chemical change to a state of lower energy, not from the phosphate bonds themselves
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cilia beating
mechanical work
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the contraction of the muscle cells
mechanical work
136
the movement of the chromosomes during
cellular reproduction
mechanical work
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the pumping of substances across
membranes against the direction of spontaneous movement
transport work
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the pushing of endergonic reactions that would
not occur spontaneously
chemical work
139
synthesis of polymers from monomers
endergonic
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ATP drives endergonic reactions by
phosphorylation
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phosphorylation
transferring a phosphate group to some other molecule
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phosphorylated intermediate
The recipient molecule after receiving the phosphate group
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ATP is a ______ regenerated from _____
renewable resource and adenosine
diphosphate ADP
144
Energy to phosphorylate ADP comes
catabolic reactions in the cell
145
Catalyst
chemical agent that accelerate a reaction without being permanently changed in the process
146
Enzymes
are catalytic proteins that change the rate of a
reaction without being consumed by the reaction
147
Are all enzymes catalysts
YES
148
Are all catalysts enzymes
NO
149
Transition state
unstable condition of reactant molecules
that have absorbed sufficient free energy to react
150
energy of activation, or activation
energy
The initial investment of energy for starting a reaction – the energy required to break bonds in the reactant molecules
151
example of an enzyme-catalyzed reaction
Hydrolysis of sucrose by sucrase
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Every chemical reaction between molecules involves
bond breaking and bond forming
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Initial energy needed to start a chemical reaction
activation energy
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Activation energy is often supplied in form of
thermal energy that reactant molecules absorb from their surroundings
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Enzymes catalyze reactions
by lowering activation energy barrier
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Enzymes do not affect
change in free energy (∆G)
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The reactant that an enzyme acts
substrate
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An enzyme binds to its substrate to form an
enzyme-substrate complex
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the reaction catalyzed by each enzyme is very specific
from the enzyme-substrate complex
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The active site
is the region on an enzyme where the
substrate binds
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Induced fit
a substrate brings chemical groups of active
site into positions that enhance their ability to catalyze reaction
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The active site can lower an EA barrier by
- Orienting substrates correctly
– Straining bonds in the substrate molecule
– Providing a favourable microenvironment
– Covalently bonding to the substrate
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In an enzymatic reaction, the substrate
binds to the active site of the enzyme
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how are substrates held together in the active site
by weak interactions
hydrogen or ionic bonds
165
An enzyme’s activity can be affected by
temperature
pH
pressure
Chemicals that specifically influence the enzyme
166
Optimal conditions favour the most
active conformation (shape) for the enzyme
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optimal temp for typical human enzyme
37 degree Celcius
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Stomach enzyme (Pepsin) optimal PH
2
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Intestinal enzyme (Tryposin) optimal PH
8
170
Cofactors
nonprotein enzyme helpers
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cofactors may be
inorganic
or organic
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inorganic cofactor
such as a metal in ionic form
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coenzyme
organic cofactor
174
coenzyme example
vitamins
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Competitive inhibitors
bind to the active site of an
enzyme, competing with substrate
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Noncompetitive inhibitors
bind to an enzyme at a
separate site from the active site
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Noncompetitive inhibitors results in
a conformational change in the enzyme that makes the active site less effective
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Examples of inhibitors include
toxins, poisons, pesticides,
and antibiotics
179
antibiotics works more on
bacteria
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ANIMAL intermediate energy
glucose and sugar
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ANIMAL immediate energy
ATP
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ANIMAL long-term energy
Fat and adipose cells
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PLANT intermediate energy
Glucose
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PLANT immediate energy
ATP
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PLANT long-term energy
oils
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photosynthesis is endergonic or exergonic
endergonic reaction
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cellular respiration is endergonic or exergonic
exergonic reaction
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more complex molecules have more energy because
the energy stored is in the bonds
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Downhill metabolic pathway
Energy is released by the downhill reactions of catabolic pathways
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uphill metabolic pathway
energy is stored and then used to drive uphill reactions of anabolic pathways
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a process on its own that leads to a decrease in entropy
Nonspontaneous process
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Organisms are ____ entropy
low
193
The greater the decrease in free energy,
the greater the amount of work that can be done
194
Why does heat not work well in biological systems?
a. High temps denature proteins and kill cells
b. Heat would speed up ALL reactions not just specific ones
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Inhibitors can attach to the enzyme by covalent bonds
irreversible
196
Most bind to the enzyme by weak interactions
reversible
197
A cell must be able to control when and where its various enzymes are active
Either by switching on and off the genes that encode specific enzymes
Regulating the activity of enzymes once they are made
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Endergonic or Exergonic
Endergonic
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Endergonic or Exergonic
Exergonic
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enzymes are _____ encoded by ____
proteins and genes
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changes or _____ leads to changes in enzyme's ______
mutations and amino acids
202
altered amino acids may alter enzyme's
substrate specificity
203
what would result if a cell's metabolic pathways were not regulated
chemical chaos
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how does a cell regulate its metabolism
1. switching on or off genes that encode specific enzymes
2. regulating activity of enzymes
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Allosteric regulation
may either inhibit or stimulate an enzymes activity
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Allosteric regulation occurs when a
regulatory molecule binds to a protein at one site and affects the protein’s functionm at another site
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Most allosterically regulated enzymes contain
multiple polypeptide subunits
208
Each enzyme has
active and inactive forms
209
Binding of an activator
stabilizes the active form of an enzyme
210
* Binding of an inhibitor
stabilizes the inactive form of an enzyme
211
Cooperativity
is a form of allosteric regulation that can
amplify enzyme activity
212
In feedback inhibition,
the end product of a metabolic pathway shuts down the pathway
213
ATP powers cellular work by
coupling exergonic
reactions to endergonic reactions
214
ATP drives endergonic reactions by
transfer of the phosphate group to specific reactants
215
cell respiration (catabolic pathway) drives the
regeneration of ATP from ADP
