Transcript Metabolism: Energy and Enzymes

Metabolism: Energy and
Enzymes
Energy
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Ability to do work, change matter
Kinetic – energy in motion
Potential – stored energy
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Chemical energy (food)
Mechanical energy (motion)
Thermodynamics
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2 Laws:
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1. Law of conservation of energy – Energy
cannot be created or destroyed, but it can be
changed from one form to another (heat energy)
2. Energy cannot be changed from one form to
another without a loss of usable energy.
When heat is released, it is not longer available to do
work, lost to the environment.
Cells are 40% efficient, rest of energy is given off as
heat
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Entropy
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Used to indicate the relative amount of
disorganization in universe
Every process that occurs in cells increases
the total entropy of the universe.
More organized = less stable
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Clean room, more organized but less stable than a
messy room
entropy clip
Metabolic reactions
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Metabolism
Reactants – products
Free energy – amount of available energy to do
work after a chemical reaction has taken place (G)
Exergonic reactions – delta G is negative, products
have less energy than the reactants, reaction is
spontaneous, energy is released, ex. ATP breakdown
Endergonic reactions – delta G is positive and
products have more free energy than the reactants.
Can only take place if there is an input of energy.
Adenosine Triphosphate
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Energy currency, universal, can be used in
many different types of reactions.
Composed of Adenine (nitrogen base), ribose
sugar and 3 phosphate groups
Uses of ATP
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Chemical work – synthesize macromolecules
Transport work – pumps
Mechanical work – muscle contraction, cilia to
beat, chromosomes to move.
Coupling reactions
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Energy released by exergonic reactions drive
endergonic reactions.
ATP breakdown is exergonic
Function of ATP
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Chemical work – helps to synthesize
macromolecules
Transport work – supplies energy for pumps
across membrane
Mechanical work – supplies energy to do
work, muscle contraction, cilia beat…