Cellular Energy: ATP

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Cellular EnergyATP Enzymes

• What is it? Where do organisms get it? How do
  they use it?

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Energy

• The capacity to perform work to rearrange matter
• 2 forms
• Potential Energy (PE) stored energy, due to
  position or structure
• Kinetic Energy (KE) Energy of motion
• Heat is KE associated with the movement of
  molecules/atoms

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Energy is transferred not created

• Total amount of Energy in Universe is constant
  (1st Law)
• Nothing created or destroyed, only transformed
• One result of ALL energy transfers is the
  production of heat (2nd Law)
• Heat disordered, unharnessed KE. This KE is
  LOST cannot be used to perform work

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Heat loss during rxns
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Chemical Reactions

• Reactants (Substrates) The starting materials
  that are consumed during a chemical reaction.
• Products The ending materials of a chemical
  reaction.
• Endergonic (energy input) Store Energy
  products have higher energy than reactants.
• Exergonic (energy output) Release Energy
  products have lower energy.

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Endergonic

• Products have more energy than reactants
• Photosynthesis
• Reactants CO2 H2O light energy
• Products sugar molecules

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Exergonic

• Reactants have more energy than products
• Bonfire
• Reactants Cellulose (glucose), O2
• Products light, heat, CO2, H2O
• Cellular respiration burns glucose to harness
  energy for work

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Anabolic and Catabolic Reactions
ANABOLIC REACTIONS
Protein
Glycogen
Triglycerides
Uses energy
Uses energy
Uses energy
Glucose
Fatty acids
Amino acids
Amino acids
Glycerol
Glucose



CATABOLIC REACTIONS
Protein
Glycogen
Triglycerides
Glucose
Amino acids
Glycerol
Fatty acids
Yields energy
Yields energy
Yields energy
Yields energy
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Cellular metabolism

• The sum of all cellular endergonic and exergonic
  rxns.
• Energy coupling (transfer) use of released
  energy to run cellular processes
• ATP provides coupling mechanism!!

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ATP

• High energy bonds join negatively charged
  phosphate groups
• Energy in bonds energy of magnetic repulsion
  (high PE!)
• Hydrolysis rxn frees trapped energy

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ATP

• Some freed energy is lost as heat
• The rest is transferred via the phosphate group
  when it binds to another molecule
  (phosphorylation)

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ATP fuels ALL cellular work
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ATP is continually regenerated
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Enzymes are also required to drive reactions
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Enzymes lower Activation Energy

• Some energy (EA) must be applied to begin a rxn
• Sometimes the energy barrier is prohibitively
  large
• Enzymes reduce that barrier, allowing rxn to
  proceed with LESS energy input

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Enzyme are not consumed, they are recycled

• Available enzyme w/ active site
• Substrate binds
• Conversion to products
• Products released

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Enzymes possess

• Ideal temperature regimes
• Ideal pH ranges
• Cofactors (inorganic molecules ions) and
  coenzymes (organic molecules)

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Competition Inhibition

• Some molecules may mimic enzymes (competitive
  inhibition)
• Either shutdown OR accelerate reaction
• Others change enzyme conformation (noncompetitive
  inhibition)
• Always shuts down reaction

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Concept Check

• Enzymes catalyze reactions in a cell. There are
  hundreds of different enzymes in a celleach with
  a unique three-dimensional shape. Why do cells
  have so many different enzymes?
• Each enzyme molecule can only be used once.
• The shape of enzymes active site generally fits
  a specific substrate.
• The substrate molecules react with enzymes to
  create new enzymes.
• Enzymes are randomly produced. With thousands of
  different shapesone is likely to work.

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Answer

• Enzymes catalyze reactions in a cell. There are
  hundreds of different enzymes in a celleach with
  a unique three-dimensional shape. Why do cells
  have so many different enzymes?
• The shape of enzymes active site generally fits
  a specific substrate.

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What fuels our bodies?

• Adenosine triphosphate (ATP)
• Creatine Phosphate (CP)
• Carbohydrates (Glucose)
• Fats

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What fuels our bodies?

• Adenosine triphosphate (ATP) THE energy
  carrying molecule in the body
• Muscles store only enough ATP for 1 3 seconds
  of activity
• ATP is generated continuously
• Usually via carbohydrate catabolism with or
  without O2

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ATP structure
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Alternative Fuels

• After depleting stored ATP, cells turn to other
  sources of energy to regenerate ATP
• Creatine phosphate (CP)
• Carbohydrates (Glucose)
• Fats

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CP transfers P to make ATP
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Glucose metabolism
In cytoplasm
In mitochondria
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Fats as fuel

• Stored triglycerides (storage form of fats) can
  be metabolized to generate ATP for
• Low intensity exercise
• Exercise of long duration
• Ex 10 hr. hike moderate climb
• Abundant energy source, even in lean people
• Provides 2x more energy per gram as carbohydrate

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Distribution

• ATP/CP
• Carbohydrates
• Fats
• Protein

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Energy use over time Increasing intensity
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Interpreting Data
0

• This graph illustrates how an enzyme catalyzes
  reactions in biological systems. From an energy
  standpoint is this reaction an endergonic or
  exergonic reaction?
• Endergonic
• Exergonic
• There is not enough information in this graph to
  decide the type of reaction.

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Answer
0

• This graph illustrates how an enzyme catalyzes
  reactions in biological systems. From an energy
  standpoint is this reaction an endergonic or
  exergonic reaction?
• Exergonic

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Interpreting Data
0

• Which of the following represents the energy of
  activation after modification by an enzyme?
• A.
• B.
• C.

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Answer
0

• Which of the following represents the energy of
  activation after modification by an enzyme?
• A.