Atp production

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ATP Production

  • AP Biology

Overview: Life Is Work

  • Living cells require energy from outside sources
  • Some animals, such as the giant panda, obtain energy by eating plants, and some animals feed on other organisms that eat plants
  • Energy flows into an ecosystem as sunlight and leaves as heat
  • Photosynthesis generates O2 and organic molecules, which are used in cellular respiration
  • Cells use chemical energy stored in organic molecules to regenerate ATP, which powers work

Adenosine Tri-Phosphate (ATP)

  • ATP is the energy unit of the cell.
  • ATP is composed of an Adeno. Group, a sugar group and three phosphates.
  • ATP is easily recycled.
  • The cell converts Adenosine Di-Phosphate (ADP) into ATP by the addition of a phosphate.

An Overview of how ATP is Produced

  • Fig. 9-2
  • Light
  • energy
  • CO2 + H2O
  • Cellular respiration
  • in mitochondria
  • Organic
  • molecules
  • + O2
  • ATP powers most cellular work
  • Heat
  • energy
  • ATP

Redox Reactions: Oxidation and Reduction

  • The transfer of electrons during chemical reactions releases energy stored in organic molecules
  • This released energy is ultimately used to synthesize ATP

The Principle of Redox

  • Chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions, or redox reactions
  • In oxidation, a substance loses electrons, or is oxidized
  • In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced)

ATP powers cellular work by coupling exergonic reactions to endergonic reactions

  • A cell does three main kinds of work:
    • Chemical
    • Transport
    • Mechanical
  • To do work, cells manage energy resources by energy coupling, the use of an exergonic process to drive an endergonic one
  • Most energy coupling in cells is mediated by ATP


  • ATP (adenosine triphosphate) is the cell’s energy shuttle
  • ATP is composed of:
    • ribose (a sugar)
    • adenine (a nitrogenous base)
    • Three phosphate groups
  • Fig. 8-8
  • Phosphate groups
  • Ribose
  • Adenine

The bonds between the phosphate groups of ATP’s tail can be broken by hydrolysis

  • The bonds between the phosphate groups of ATP’s tail can be broken by hydrolysis
  • Energy is released from ATP when the terminal phosphate bond is broken
  • This Third Phosphate bond contains LOTS of Energy
  • This release of energy comes from the chemical change to a state of lower free energy, not from the phosphate bonds themselves
  • Fig. 8-9
  • Inorganic phosphate
  • Energy
  • Adenosine triphosphate (ATP)
  • Adenosine diphosphate (ADP)
  • P
  • P
  • P
  • P
  • P
  • P
  • +
  • +
  • H2O
  • i

How ATP Performs Work

  • The three types of cellular work are:
    • mechanical
    • transport
    • chemical
  • Each is powered by the hydrolysis of ATP
  • In the cell, the energy from the exergonic reaction of ATP hydrolysis can be used to drive an endergonic reaction
  • Fig. 8-11
  • (b) Mechanical work: ATP binds noncovalently
  • to motor proteins, then is hydrolyzed
  • Membrane protein
  • P
  • i
  • ADP
  • +
  • P
  • Solute
  • Solute transported
  • P
  • i
  • Vesicle
  • Cytoskeletal track
  • Motor protein
  • Protein moved
  • ATP
  • ATP


  • ATP drives endergonic reactions by phosphorylation, transferring a phosphate group to some other molecule, such as a reactant
  • The recipient molecule is now phosphorylated


  • The process of Phosphorylation converts a relatively low energy compound (ADP) into a higher energy compound (ATP)
  • ADP (Adenosine Di-Phosphate)- Contains an Adenosine, a ribose group, and two Phosphate groups.
  • Fig. 8-12
  • P
  • i
  • ADP
  • +
  • Energy from
  • catabolism (exergonic,
  • energy-releasing
  • processes)
  • Energy for cellular
  • work (endergonic,
  • energy-consuming
  • processes)
  • ATP
  • +
  • H2O

The ATP Cycle

  • ATP can be produced from existing ADP molecules
  • A phosphate is added to ADP at the mitochondria.
  • Requires ATP synthase - A protein complex in the mitochondria that acts a molecular mill and converts ADP into ATP.
  • Fig. 9-UN7
  • INTER-
  • H+
  • ATP
  • synthase
  • ATP
  • ADP +
  • P
  • i
  • H+
  • MITO-

The Regeneration of ATP

  • ATP is a renewable resource that is regenerated by addition of a phosphate group to adenosine diphosphate (ADP).
  • Requires ATP synthase and H ions (from water.)
    • The energy to phosphorylate ADP comes from catabolic reactions in the cell.
    • The chemical potential energy temporarily stored in ATP can then be used to drive most cellular work.

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