Metabolism, Energy,

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Metabolism, Energy, Life

• Metabolism
• Totality of an organisms chemical processes
• Catabolic pathways (release energy)
• Breakdown
• Respiration
• Anabolic pathway
• Build up
• Photosynthesis

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Metabolism, Energy, Life

• Energy
• Capacity to do work or cause change
• Kinetic energy (energy of motion)
• Potential energy
• capacity of matter to cause change as a
  consequence of its location or arrangement.
• Chemical energy
• A form of potential energy that is available for
  release in chemical reactions.

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Metabolism, Energy, Life

• Free energy (?G)
• The portion of a systems energy that can perform
  work when temperature is uniform throughout the
  system.
• Energy available for work.
• Exergonic reactions
• Negative ?G
• Endergonic reactions
• Positive ?G

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Metabolism, Energy, Life

• ATP
• Adenosine triphosphate
• Powers cellular work by coupling exergonic
  reactions to endergonic reactions.
• ATP Cycle

ATP
Energy for Cellular work
Energy from catabolism
ADP Pi
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EnzymesBiological Catalysts

• Speed up the rate of a reaction.
• Unchanged by the reaction.
• Lower the Activation Energy required for the
  reaction to go forward.
• Do not change the ?G for reaction.
• Substrate specific
• Active site compatible to substrate
• Forms enzyme-substrate complex
• Induced fit model

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Effects of Local Conditions on Enzyme Activity

• Temperature and pH
• Speed of an enzyme-catalyzed reaction may
  increase with rising temperature or pH up to the
  point at which increase thermal agitation or
  acidic/basic conditions begins to disrupt the
  weak bonds and interactions that stabilize
  protein shape.
• Cofactors
• Small molecules that bind either permanently or
  reversibly with enzymes and are necessary for
  enzyme function
• Inorganic metal ions or organic coenzymes
• Most vitamins are coenzymes or precursors of
  coenzymes.
• Each enzyme has optimal conditions.

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Enzymes Inhibitors

• Competitive inhibitors
• Compete for the active site.
• Reversible
• Increasing the concentration of substrate
• Noncompetitive inhibitors
• Do not directly compete with the substrate at the
  active site.
• Bind to another part of the enzyme
• Change in shape, altering the active site.
• nonnreversible
• Pesticide DDT Many antibiotics

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Control of Metabolism

• Allosteric Regulation
• Regulatory molecules that change an enzymes
  shape and function by binding to an allosteric
  site.
• Allosteric site
• A specific receptor site on some part of the
  enzyme molecule, separate from the active site.
• Effect
• Inhibition or stimulation of enzyme active

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Control of Metabolism

• Allosteric Regulation
• Allosteric activator
• Allosteric inhibitor
• Feedback Inhibition