Transcript Energy!!

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Energy is the capacity to do work
Energy is measured in kcals or joules
Examples: Kinetic, Thermal, Potential,
Chemical
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Energy cannot be created or destroyed in a
reaction; It can only be transformed
Ex: Photosynthesis: Conversion of
____________ energy to _____________ energy!
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Living systems need to continually acquire and
transform energy in order to do work
necessary to remain alive (“metabolism”)
Ex: grow, repair, move, reproduce!
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The energy available in a system to do work
(Ex: transport, synthesis, reproduction, growth)
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Every time energy is
transformed, some of the
energy becomes unusable
and the entropy of the
universe increases
Ex: Cell Respiration:
__________ of the
chemical energy is
converted and used for
cellular work; _________
generates heat!
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Cells of Organisms process more ordered
forms of matter into less ordered forms that are
returned to the environment
Ex: Digestion followed by Cell Respiration!!
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Entropy is the amount of disorder or
randomness in a system
Ex: Your messy room
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a. Hydrolysis of Proteins into Amino Acids:
b. Synthesis of Glycogen from Glucose:
c. Photosynthesis:
d. Digestion of a cheeseburger:
e. Transcription of DNA into mRNA:
f. Cellular Respiration:
g: A plant using raw materials to build a leaf in
the spring:
h: Leaves decomposing in winter
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Matter and energy
move into living
systems from the
environment. Living
Systems transform
matter and energy and
return it in less ordered
forms/low energy to
the environment!!
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Insufficient free
energy production
leads to disease and
death!
Entropy INCREASES
What if this happens
at the producer level
of an ecosystem??
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Multi-Step Metabolism!
Free Energy production occurs in multiple-step
pathways, mediated by enzyme catalysts
“slow burn” energy production
Increases efficiency!
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Exergonic reactions release free energy (from
covalent bonds) and therefore are
spontaneous reactions (following activation)
Ex: Cellular Respiration, catabolism,
digestion of polymers, decomposition
Endergonic reactions require an input of
energy and therefore are not spontaneous
 These reactions form products that have high
chemical energy (stored)
 Ex: Photosynthesis,
Anabolism, Synthesis of
Polymers from monomers
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Used to determine if a process can occur
spontaneously or not
ΔG = ΔH – TΔS
ΔG = change in free energy
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ΔH = change in enthalpy for the reaction
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(- = exergonic, + = endergonic)
(- = exothermic, + = endothermic)
T = Kelvin temperature
ΔS = change in entropy
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(+ = entropy increases, - = entropy decreases)
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Rxn 1: A + B —> AB
ΔH: +245 KJ/mol
ΔS: -.02 KJ/K
Reaction 2: CD —> C + D
ΔH: -334 KJ/mol
ΔS: +.12 KJ/mol
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ΔG = ΔH – TΔS
If ΔG is negative, free energy is released
(reaction will occur spontaneously and is
exergonic)
If ΔG is positive, free energy is
consumed (reaction will not occur
spontaneously and is endergonic)
If free energy is not available, the
reaction does not occur.
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An exergonic reaction…is negative, will
release free energy, and will occur
spontaneously
An endergonic reaction…is positive, requires
the continuous input of energy and is not
spontaneously (without free energy available,
no reaction occurs)
Energy
Is ΔG positive or
negative
Exergonic or
Endergonic?
Spontaneous?
Products have more or
less energy than
reactants?
Energy
Time
Time
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Catabolic reactions release energy that can be
used to drive anabolic reactions
They work TOGETHER
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ATP!
Nucleoside
 Adenine Base
 Ribose Sugar
 3 phosphate
Groups
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Which form has more energy stored: ATP or ADP
or AMP?
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Captures and releases free energy
Releases a large amount of energy when
hydrolyzed
Can phosphorylate other molecules to transfer
energy (adding a phosphate group)
Energy is stored in the covalent bonds between
phosphates
ATP:
Adenosine Triphosphate
Phosphate
group
P
P
P
Adenine
Ribose
Hydrolysis
P
ADP:
H2O
P
Adenosine Diphosphate
P
Energy
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ΔG = -7.3kcal when ATP -> ADP + Pi
Energy
Time