Energy

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Primary Secondary
Tertiary
Quaternary
Protein Structure
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Energy
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Outline

• I. Introduction
• A. Metabolism
• B. Energy defined
• II. Laws of Thermodynamics
• III. Energy Transfer in Living Systems
• A. Chemical Reactions
• B. ATP

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Metabolism

• All the chemical reactions that occur in the cell
• Capacity to get and use energy to build, store,
  break down, and eliminate substances necessary
  for growth and reproduction
• Catabolism reactions that break down large
  molecules into smaller ones e.g. digestion
• energy released
• Anabolism reactions that build larger molecules
  from small ones e.g. protein built from AA
  subunits energy required

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Energy

• Definition the ability to do work, cause change
• Energy obtained from some cellular reactions is
  used for fueling other reactions
• Thermodynamics The study of energy

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Laws of Thermodynamics

• 1st Law Energy in the universe is constant
• Energy can be transferred or transformed but it
  cannot be created or destroyed
• Also known as the Energy Conservation law
• True for a closed system

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Heat and Entropy

• Heat is energy and can do work (steam engine)
• Conversion of any form or energy into heat is not
  fully reversible, not all heat is usable energy
• Heat lostenergy no longer capable of doing
  work
• Heat is low quality energy
• Unusable heat associated with disorder (entropy)
• Energy flows from high quality to low quality

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Laws of Thermodynamics

• 1st Law Energy in the universe is constant
• Energy can be transferred or transformed but it
  cannot be created or destroyed
• Also known as the Energy Conservation law
• True for a closed system
• 2nd Law Disorder in the universe is increasing
• Entropy measure of disorder
• In a closed system entropy increases

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Maintaining Order

• Systems tend toward disorder
• How do you explain order of a cell, or an
  organism?
• Input of energy required to maintain order

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Energy Transfer in Living Systems

• Each chemical reaction in a cell has reactants
  and products
• 2 types of chemical reactions
• Exergonic energy released meaning reactants
  have more energy than products. Occur
  spontaneously
• Endergonic energy required meaning reactants
  have less energy than products
• Sometimes these reactions are coupled

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Energy Transfer in Living Systems

• Metabolic Pathway series of chemical reactions
• Often have reactants which are complexed into one
  or more intermediates before final products
• A B ? C ? D ? E F
• Where A, B are reactants C, D are intermediates
  E,F products
• Specific enzymes required at each step (each
  arrow)
• Chemical equilibrium recall this occurs when
  forward and backward reactions occur at the same
  rate. Concentrations of reactants and products
  are stable but not necessarily equal

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Metabolic Pathway with inhibition
(subtraction symbols)
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ATP

• Adenosine triphosphate
• Nucleotide based molecule- ribose, adenine, and
  3 phosphate groups
• Cellular energy, powers cellular work
• Bonds between phosphate groups can be broken by
  hydrolysis
• ATP H2O ? ADP Pi (inorganic phosphate)
  energy
• Phosphate groups all negative-repulse each other,
  like a coiled spring

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ATP molecule
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ATP hydrolysis