Energy and Food - Life Sciences Outreach at Harvard University

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Transcript Energy and Food - Life Sciences Outreach at Harvard University

Summer 2009 Workshop
in Biology and Multimedia
for High School Teachers
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
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Energy is a critical part of your
everyday life.
Energy is either released or
absorbed in a chemical
reaction. This occurs when the
bonds between the atoms are
broken and then the atoms
rearranged.
The food you eat is the fuel
which will provide the energy
you need to sustain life.
http://en.wikipedia.org/wiki/File:MyPyramidFood.svg
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
http://en.wikipedia.org/wiki/Carbon
The food you eat is considered to be an
Organic compounds contain
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
.
Reactions that absorb energy are called
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Reactions that
release energy
are called
http://en.wikipedia.org/wiki/File:ThermiteFe2O3.JPG
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Digestion is the
physical and
chemical
processes used
to break down
food into smaller
molecules that
can be absorbed
by the human
body.
http://en.wikipedia.org/wiki/File:Macaca_arctoides.png
http://www.whfoods.com/genpage.php?tname=faq&dbid=16
Look
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
RELEASE
ENERGY
Metabolism refers to all the
chemical reactions within an
organism that breakdown
molecules to release
energy and all the reactions
that use energy to build
complex molecules. These
reactions are referred to as
ABSORB
ENERGY
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
http://en.wikipedia.org/wiki/File:Animal_mitochondrion_diagram_en_%28edit%29.svg
When we speak of
energy we are
talking ….
Catabolism is the
process where larger
molecules are broken down
into smaller molecules
releasing energy. The
molecules are broken down
into either simple sugars,
glycerol and fatty acids or
amino acids. This process is
exothermic.
http://commons.wikimedia.org/wiki/File:Catabolism.svg
http://commons.wikimedia.org/wiki/File:FlameV1.png
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Anabolism is the process
where smaller molecules
are combined to form larger
more complex molecules.
This process requires
energy so it is considered
an endothermic
reaction.
http://commons.wikimedia.org/wiki/File:Peptidbinding.svg
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
The change in energy is measured
in terms of heat. The amount of
energy (heat) that is contained
within the bonds of the reactants is
compared to the amount of energy
(heat) that is contained within the
bonds of the products. This is
referred to as the
H.
This symbol means the difference in Enthalpy.
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
ENTHALPY
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Endothermic reactions always have a positive
H.
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Exothermic reactions always have a negative
H.
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
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Enthalpy changes that are measured when reactants
are in their standard states are called STANDARD
ENTHALPY CHANGES.
STANDARD ENTHALPIES are denoted by ∆ H˚.
Standard states are at 25˚ C and 1 atm of pressure.
The enthalpy change in a reaction is directly related to
the amount of reactants.
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Hess’s Law
states that if a series of
reactions are added
together, the enthalpy
change for the net reaction
is the same as the sum of
the individual reactions.
Huh?
More simply put:
2+2=4
is the same as
1+1+1+1=4
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
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The subject of calorimetry studies the flow of heat and
heat measurements.
Every object has the ability to absorb heat. The amount of heat
that is absorbed is referred to as the heat capacity.
The heat capacity is the amount of heat required to raise
the temperature by 1˚C.
The heat capacity depends on the composition and the amount
of the substance,
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
The heat capacity of one gram
of a substance is referred to as
the SPECIFIC HEAT.
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
The specific heat of
water is 4.184 J/g·Cº.
This means that 4.184 J
of heat is needed is
needed to raise 1 gram
of water 1ºC.
1calorie= 4.184 J
1000calories=1
kilocalorie or CAL.
http://en.wikipedia.org/wiki/File:Thermometer_CF.svg
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
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Kilocalories are used in
nutrition.
Calorimeters are used to
figure out the calories in
food sources.
https://vinstan.wikispaces.com/file/view/calorimeter.PNG
http://en.wikipedia.org/wiki/File:Nutrition_label.gif
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
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The catabolism of food is an oxidative reaction.
Most of our energy comes from Calories found in fat and
sugar.
C6H12O6 (s) + 6 O2 (g)  6 CO2 (g) + 6 H2O (l)
H = -2816 kJ
EXOTHERMIC
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
C57H110O6 (s) + 163/2 O2 (g)  57 CO2 (g) + 55 H2O (l).
rH = -37.8 x 104 kJ
EXOTHERMIC
Twice the energy as proteins and glucose!
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Catabolism
Fuels
and
O2
CO2
water
ATP
ADP
P
Cellular
Processes
Anabolism
IN SUMMARY!!!
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.