Energy and Metabolism

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Energy and Metabolism
KEY WORDS Energy Free Energy (?G) Potential
energy Kinetic energy Enzyme Substrate Activation
energy Exergonic reaction Endergonic
reaction Catalyst ATP/ ADP
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Energy

• The capacity to do work

• Move matter

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Types of energy

• Kinetic
• Potential

• Question __________ is an example of kinetic
  energy, and __________ is an example of potential
  energy.
• Fire a piece of wood
• A loaded gun a flying bullet
• A rock on top of a hill a rock rolling down the
  hill
• None of these are correct.
• All of these are correct.

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Chemical Energy
-high energy electrons

• Stored in chemical bonds

• Some molecules store a lot of energy

• Some molecules store much less

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Chemical Energy

• Energy can be transferred/transformed

Sugar oxygen ? carbon dioxide water
heat
C6H12O6 O2 ? CO2 H2O
Energy
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First Law of Thermodynamics

• Energy neither created nor destroyed
• Converted from one form to another
• Exchanged between substances

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Second Law of Thermodynamics
All exchanges of energy increase the entropy of
the universe

• Entropy
• Disorder or randomness of a system

• Heat is most disorganized form of energy
• Reactions that ? entropy happen spontaneously
  release energy

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Two laws of thermodynamics
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Energy Transformed
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Exergonic Reactions

• Release energy

• Spontaneous

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Endergonic Reactions

• Not Spontaneous

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Question Which of the following reactions is
endergonic?

1. CO2 and H2O Glucose
2. Amino acids Proteins
3. Triglycerides Fatty acids
4. Ions moving across membrane from an area of high
   concentration to an area of low concentration.

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Question

• Which of the following reactions releases energy?
• CO2 and H2O Glucose
• Amino acids Proteins
• Triglycerides Fatty acids
• Ions moving across membrane from an area of high
  concentration to an area of low concentration.

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Coupled Reactions
Exergonic provides energy for the endergonic
Endergonic
Exergonic
Protein
Energy
Energy
glucose
Amino acids
CO2 H2O
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Living organisms
Metabolism

• All chemical reactions in an organism

Anabolism
Catabolism
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Living organisms

• Capture energy to drive chemical reactions.

• Convert raw energy into usable form

• Sunlight, food

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The structure and hydrolysis of ATP
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ATP the Cells Rechargeable Battery

• ATP energy ADP charged
  battery dead battery
• This energy can then be used to run an energy
  requiring reaction.

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The ATP cycle
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According to the first law of thermodynamics,
energy

1. is never lost or gained, but is only transformed
2. always requires an ultimate source such as the
   sun
3. can never be gained, but can be lost
4. can never really be harnessed
5. can never be transformed

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Each time there is a chemical reaction, some
energy is exchanged. According to the second law
of thermodynamics, with each exchange

1. Some energy is lost, but other energy is created.
2. Some energy must come from the sun.
3. Some energy is transformed into heat.
4. Energy is gained for future use.
5. Some energy is permanently and completely
   destroyed.

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ATP stores energy in the form of

1. mechanical energy
2. heat
3. complex carbohydrates
4. chemical bond energy
5. amino acids

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The complexity of metabolism
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Equation Gibbs Free Energy
?G ?H T?S
Energy NOT available for work
Energy available for work
All energy
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The relationship of free energy to stability,
work capacity, and spontaneous change
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Energy changes in exergonic and endergonic
reactions
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Energy profile of an exergonic reaction
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Disequilibrium and work in closed and open
systems
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Is ?G for an exergonic reaction positive or
negative?
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What is the difference betweenAnabolismCatabol
ismMetabolism
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From an energy perspective, when is equilibrium
reached?
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Enzymes
KEY WORDS Enzyme Activation energy Catalyst Subs
trate Active site Induced fit Coenzyme Allosteric
site Competitive inhibitor Noncompetitive
inhibitor Feedback inhibition
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Enzymes and Shape
Active Site
Induced fit Handshake between substrate and
enzyme
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Activation Energy
Activation Energy
Net Energy Released
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Enzymes

• Proteins that speed up chemical reactions
  (catalysts)

• Lower activation energy for a reaction

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Enzyme reactions can be simplified as

• S Substrates (reactants) enter reaction.
• P Product (what you get at the end) result
• E Enzymes mediate specific steps

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The catalytic cycle of an enzyme
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Enzymes
Key Points

• Catalyze reactions

• Dont change reactions

• Same net release/use of energy

• Enzymes are not changed by reaction

• Each enzyme catalyzes a specific chemical reaction

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Enzymes lower the barrier of activation energy
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Which of the following will lower the activation
energy of a reaction in a cell?

1. lowering the temperature
2. lowering the pressure
3. using an enzyme
4. changing the amount of the reactants
5. supplying ATP

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Which of the following will lower the activation
energy of a reaction in a cell?

1. lowering the temperature
2. lowering the pressure
3. using an enzyme
4. changing the amount of the reactants
5. supplying ATP

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Enzymes

1. accelerate specific chemical reactions
2. are not chemically altered by binding with a
   substrate
3. lower the activation energy of specific chemical
   reactions
4. all of the above
5. a and c only

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4 Things that Affect Enzyme Activity

1. Substrate concentration
2. Enzyme concentration
3. pH
4. Temperature

Shape of enzyme (Protein denatured)
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Environmental factors affecting enzyme activity
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Enzyme Regulation

• Enzymes can be turned on and off
• Regulated by other molecules in the cell
• Examples
• Allosteric regulation
• Feedback inhibition
• Inhibitors

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Inhibition of enzyme activity
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Allosteric regulation of enzyme activity
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Feedback inhibition
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If an enzyme solution is saturated with
substrate, the most effective way to obtain an
even faster yield of products is

1. Add more enzyme
2. Heat the solution
3. Add more substrate
4. Add an allosteric inhibitor
5. Add a noncompetitive inhibitor

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An enzyme accelerates a metabolic reaction by

1. Altering the overall free energy change for the
   reaction
2. Making an endergonic reaction occur spontaneously
3. Lowering the activation energy
4. Pushing the reaction away from equilibrium
5. Making the substrate molecule more stable

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Some bacteria are metabolically active in hot
springs because

1. They are able to maintain a cooler internal
   temperature
2. High temperature facilitates active metabolism
   w/o need of catalysis
3. Enzymes have high optimal temperatures
4. Enzymes are insensitive to temperature

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Glycolysis is a metabolic pathway that helps
living things extract energy from food. From this
we know that glycolysis

1. consists of a series of chemical reactions
2. uses a number of enzymes
3. involves the modification of a series of
   substrates
4. proceeds by means of each enzyme leaving a
   succeeding reaction to a different enzyme
5. all of the above