Download Metabolism and energy

Metabolism and Energy
I. Metabolism and Energy
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Metabolism- the totality of an organism’s
chemical reactions
Catabolism
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Catabolic pathways - break down compounds
Anabolism
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Anabolic pathways- build up compounds
Energy
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Provides the ability to do work
Potential Energy
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The energy stored in an object
Carbohydrates and lipids
Enthalpy – energy stored in bonds
of a molecule
Covalent bonds = stored potential energy
 Nutrients (carbohydrates etc.) have energy
(calories) in their bonds
Kinetic Energy
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The energy of a moving object
When food energy is released it turns into
kinetic energy of molecules
Eg. Burning, metabolism
Calorie
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One calorie is the ENERGY required to raise 1
gram of water 1 degree C
Nutrition calories are Kilocalories and will raise 1
Liter of water 1 degree C
1000 calories = 1 Calorie = 1 kcal
2 regular water
bottles = 1 liter
raised 1 degree C
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Calorimeter measures calories
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Food is Burned! Water temp rise measured
Thermodynamics
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Thermo = heat
Dynamics = changes
The study of changes in energy and heat
First Law of Thermodynamics
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“Conservation of Energy” .
Energy can NOT be created or destroyed,
but it can be changed
E=MC2
Does Einstein's equation contradict the law
of conservation of energy?
In a nuclear reaction Matter converts to
energy, but is still conserved
Energy transformation
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Living things must transform energy into
usable form. Sugar  ATP
Second Law of thermodynamics
Systems tend to change in a way that tends
to increase disorder.
Disorder of universe is increasing!
“Entropy” = order  disorder
Entropy is a fact of Life
"Now, in the second law of thermodynamics..."
reproduced with permission, Copyright © by Sidney Harris
Entropy affects everything
Entropy happens
Life – combats entropy
Living things have complex organization and
systems to combat entropy
Heat
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Entropy most commonly takes the form of
heat loss where energy is spread out
Non living and dead things lose energy
quickly as HEAT loss
Free Energy
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Energy that is carefully stored for further
use
Living things “burn” calories to produce
free energy compounds
Sugar + Oxygen  carbon dioxide + ATP
A wolf produces heat and free
energy
Free energy potential
Energy released
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Unstable
More free energy
Less entropy
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Stable
Less free energy
More entropy
Decomposition reaction
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Energy is released
Energy released
C6H12O6
more E
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CO2 + H20
less E
Δ G = change in (Δ) Free energy (G)
G = Gibbs free energy
limits the system energy to the cell
Equation for change in free energy
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ΔG = Δ G2 – Δ G1
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Free energy = final energy – initial energy
ΔG determines reaction
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Neg - ΔG spontaneous
Pos + ΔG not spontaneous
Endergonic vs. exergonic reactions
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Endergonic = + ΔG needs Energy to occur
stores energy in products
Exergonic = - ΔG releases Energy.
Products have less energy
Exergonic ex.
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Uses up free energy
Energy
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C6H12O6 + O2
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ΔG -686 kcal/mol
CO2 + H20
Ex. Endergonic requires free
energy
Energy
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2H2 + O2
2H2O
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Energy required to synthesize water!
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+ ΔG
Free energy equation
ΔG = ΔH – T ΔS
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ΔG= free energy
ΔH = enthalpy energy in chemical bonds
(Available energy)
T = temperature (degrees Kelvin)
ΔS = entropy (Unavailable energy)
ATP
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Adenosine Tri Phosphate
The energy “currency” of living things
ATP
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Adenosine = Adenine + Ribose
Tri = three
Phosphate = 1 Phosphorus, 4 oxygens
ATP stores FREE energy
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Sugar + Oxygen  CO2 + H2O + ATP
Free energy (ATP) is energy available for
work in the body (muscles etc.)
Phosphate bonds
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ATP’s energy is stored energy in
Phosphate bonds
ATP forms ADP
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Energy is released when the high energy
Phosphate bond is broken
Hydrolysis of ATP
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ATP + H2O
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ΔG = -7.3 kcal/mol ---- Exergonic!!
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ADP + Pi
Happens spontaneously – can be used to power
cell reactions
Cellular work requires ATP
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The free energy released from ATP can be
used to do work
Needed by endergonic reactions
Without Free energy
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Energy is lost as heat
Cellular work requiring ATP
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A) Mechanical work – moving cilia, muscle
contraction, moving chromosomes
B) Transport work – Active transport
C) Chemical work – Non-spontaneous
reactions
Energy coupling
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The use of an exergonic reaction to push
an endergonic reaction
Without ATP
A
+
B
ΔG = 3.4 kcal/mol Endergonic
NEEDS ENERGY
AB
With ATP
1)
ATP
+
A
P
A
+
ADP
2)
A
A+B
ATP
P
+
AB
P
B
AB
+
ΔG = 3.4
ΔG = -7.3
ΔG = -3.9 EXERGONIC!
P
Redox reactions
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These are also coupled reactions.
Oxidation of one molecule, such as ATP,
supplies energy to reduce another
molecule
Oxidation – loss of electrons. Exergonic
Reduction – gain of electrons. Endergonic