Download Energy and Metabolism

 Small
molecules are assembled
into polymers, which may be
hydrolyzed later as the needs of
the cell change.
 Please provide me an
example…right now.
 What
is it?
 How many chemical reactions at
any given time?
 Examples of metabolic pathways?
 Light
Energy
 Kinetic energy
 Heat, or thermal energy
 Potential energy
 Chemical energy
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Energy - The capacity to cause change
Kinetic energy - energy associated with the
relative motion of objects.
Heat, or thermal energy – the kinetic energy
associated with random movement of atoms
or molecules.
Potential energy - energy that matter
possesses because of its location or
structure.
Chemical energy – used in biology to refer
to the potential energy available for release
in a chemical reaction.
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Metabolism manages material and energy
resources (studying the latter is known as
bioenergetics) throughout the cell or cells in
an organism using grouped chemical
reactions called metabolic pathways.
What does managing material and energy
resources mean?
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Two kinds of pathways help with this
“management” – either breaking down
(catabolic) or building up (anabolic).
When groups of anabolic and catabolic
reactions (pathways) work together and
transfer energy, we say they are energy
coupling.
What do we study?
 Where do we study them?
 What do we call the matter under
study?
 What do we call everything else?
 What kind of system are you?
 Are you phlying in the phace of the
second law of thermodynamics?
 “Organisms are islands of low entropy
in an increasingly random universe.”
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Chemical reactions and free energy.
 Free energy is available for work, but
the system that contains it needs a
little push.
 ΔG = ΔH – TΔS
 Spontaneous reactions cause the
system they happen in to lose free
energy. Where does the lost energy
go?
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Enzymes lower the push that is
needed by lowering the activation
energy (EA).
 Provide a place where conditions allow
for substrate to react more easily (for
both catabolic and anabolic reactions
in metabolic pathways).
 Go to animation on website…
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Exergonic reactions release free energy (like
burning wood), but in our bodies, we harness
most of it as ATP through a series of enzyme
catalyzed reactions.
Because they release free energy, a - ∆G
results which means these reactions make
energy available to be harnessed.
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Endergonic reactions use free energy
harnessed from exergonic ones in the form of
ATP (remember that free energy has other
forms than ATP).
Because they take up free energy, a + ∆G
results which means these require energy to
proceed.
 How
come we never reach
equilibrium?
 Metabolic
disequilibrium is
maintained because we constantly
exchange materials with the
environment.
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Recall that bioenergetics is the study of
energy management in living things.
Management of energy in living things
usually comes as a result of coupling
downhill and uphill reactions.
Energy that would have been lost as heat in
the breakdown of glucose is conserved
when it is transformed to ATP.
ATP supplies the energy for most cellular
processes. What are they?
 Enzymes
are catalytic
proteins.
 What does every chemical
reaction between molecules
involve?
Get up to the top!
HOT STUFF!
The laws of thermodynamics favor the
breakdown of large highly ordered
molecules such as…
 Thank goodness for activation energy.
 On the other hand, we need some
reactions to happen for life to persist.
What are our options without
enzymes?
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Because they have an ___________.
 When reactants (known as __________)
bind with the enzyme, an _________
results.
 What does the induced fit cause?
 They cause a change in the position of
key parts of active site that can make
it easier for the reaction to occur
(because it lowers _________).
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 How
is the substrate usually held
in the active site?
 What decides which way the
enzyme will allow a reaction to
progress?
 So dang fast!
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What are they?
Orient the substrate molecules so they are
more likely to react.
Putting physical stress on the bonds of the
substrate – getting them closer to the
______________ state?
Creating chemical microenvironments.
Participating in the catalytic reaction by
doing what?
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Enzymes have 3D shape.
An unfolding of the enzyme means it has
been ____________.
What kinds of environmental conditions can
do this?
The temperature or pH that enzymes work
best at are called ___________ temperature or
pH.
Thermus aquaticus, your stomach, your cells,
etc.
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Cofactors. What are they?
What’s the difference between cofactors and
coenzymes? Coenzymes are typically
_____________.
How do they help?
What about inhibitors?
Where do the work?
Competitive and non-competitive ones.
Toxins are irreversible. Sarin and
acetylcholinesterase – what’s the big deal?
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Why can’t enzymes run amok?
We can regulate the genes that code for them
or we can regulate them once they’ve been
made.
Allosteric regulation can do two things. What
are they?
Inhibit or activate the enzyme.
What level of protein folding have we reached
with allosteric enzymes? Why?
Allosteric
inhibition/activation
cooperativity