Energy

  • Capacity to do work
  • Kinetic
    • Energy possessed by an object because it is in motion
  • Potential/Chemical Potential
    • Stored energy: the energy an object has because of its location or chemical structure
  • Study of energy and its transformations
  • System
    • Object being studied
    • Three Types
      • Isolated System
        • Does not exchanged matter or energy with surroundings
        • Ex. Insulated thermos bottle
        • Closed System
          • Can exchange energy but not matter with surroundings
          • Ex. Earth
          • Open System
            • Both matter and energy can move freely between system and surroundings
            • Ex. Anything living
  • Surroundings
    • Everything outside the system
  • Energy can be transformed from one form into another or transferred from one place to another, but it cannot be created or destroyed
  • Ex. Niagara Falls
  • Energy transformations are not always efficient
    • Energy is lost and unable to do work
    • Lost in the form of heat (random molecular motion)
  • Every energy transformation increases the disorder/randomness of the universe (Entropy)
  • Disorder of an isolated system always increase (entropy)
  • Physical objects always break down
  • Proteins always break down
  • Quality of all life: highly ordered
    • Ex. DNA helix, protein, ribosome
  • Living cells = open systems
    • Exchanging energy and matter with surroundings and use that to generate order
  • Eat food to maintain low entropy
  • Living things give off heat and carbon dioxide (obeys 2nd law by increasing order)
  • No input of energy is required
  • Products have lower potential energy than the reactants
    • Potential Energy = Enthalpy (H):
    • ΔH = Hfinal – Hinitial
    • Exothermic: -ΔH
      • Release energy
    • Endothermic: +ΔH
      • Absorb energy
  • Products are less ordered than the reactants
    • Products have greater entropy
    • Entropy (S) increases
  • Portion of a system’s energy that is available to do work

Thermodynamics

First Law of Thermodynamics

  • Energy can be transformed from one form into another or transferred from one place to another, but it cannot be created or destroyed
  • Ex. Niagara Falls

Second Law of Thermodynamics

  • Energy transformations are not always efficient
    • Energy is lost and unable to do work
    • Lost in the form of heat (random molecular motion)
  • Every energy transformation increases the disorder/randomness of the universe (Entropy)
  • Disorder of an isolated system always increase (entropy)
  • Physical objects always break down
  • Proteins always break down

Life & Second Law of Thermodynamics

  • Quality of all life: highly ordered
    • Ex. DNA helix, protein, ribosome
  • Living cells = open systems
    • Exchanging energy and matter with surroundings and use that to generate order
  • Eat food to maintain low entropy
  • Living things give off heat and carbon dioxide (obeys 2nd law by increasing order)

Spontaneous Reactions

Gibbs Free Energy

∆G = ∆H – T∆S

∆ G = G final state – G starting state

Contributions of Enthalpy & Entropy

  • High Free Energy
    • Less stable
    • Greater work capacity
  • Systems spontaneously change into more stable state
    • Ex. Glucose into carbon dioxide
    • Ex. Concentration gradient
  • Transformation from solid > liquid > gas allows for an increase in entropy

Adenosine Triphosphate

  • Contains large amounts of free energy due to high-energy phosphate bonds
  • Phosphate groups closely associated with each other – negative charges repel = bonding arrangement unstable
  • Removal of phosphate group – spontaneous reaction – releases large amounts of free energy
  • Hydrolysis reaction = warming reaction – DOES NOT OCCUR (RARELY) IN CELLS
  • Energy Coupling
    • ATP is brought into close contact with reactant group
    • Terminal phosphate group is transferred to the reactant molecule making it less stable (phosphorylated)
      • High phosphoryl group transfer potential
    • Enzyme mediated (active site does not bind to water – only ATP and reactant molecule)

Equilibrium & Open Systems

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