• Cell respiration is the controlled release of energy from organic compounds to produce ATP
• Respiration is a?series of chemical reactions?that happens in?every cell
• Its purpose is to?release energy?in usable forms from the chemical energy stored in food e.g. glucose
• Respiration is a?catabolic?process
• Glucose?is the main respiratory fuel used in cells
  • Lipids?and?proteins?can also be used
• Organic?food substances contain?a lot of chemical energy
• This?energy cannot be released in one, uncontrolled step?in cells, which would cause cell damage and tissue death
• Enzymes?control the release of energy?through a series of chemical reactions called a?pathway
• This ends in the production of?ATP?(adenosine triphosphate)
  • To make ATP, a?phosphate group?is linked to adenosine diphosphate (ADP)
  • This process?requires energy?which comes from the breakdown of organic molecules
• The energy that is released is used for
  • Fuelling?anabolic?processes
  • Muscle contraction
  • Fuelling?active transport
  • Moving molecules around the cell
  • Generating heat?to maintain body temperature in warm-blooded animals

• ATP is a?source of energy?for cellular processes
• The energy can be released?immediately, exactly when it is required
• All organisms require a?constant supply of energy?to maintain their cells and stay alive
• This energy is required:
  • In?anabolic?reactions – synthesizing larger molecules from smaller molecules
  • To?move molecules?across the cell membrane (active transport)
  • To move substances and organelles within the cell
  • In animals, energy is required:
    • For?muscle contraction?– to coordinate movement at the whole-organism level
    • In the?conduction of nerve impulses, as well as many other cellular processes
• In all known forms of life, ATP from respiration is used to transfer energy in?all energy-requiring processes?in cells
• ATP is converted to?ADP?and?phosphate?when releasing its energy
  • ADP and phosphate can then be?re-converted to ATP?during respiration
• Organisms require a?constant supply of ATP?because much of the energy is dissipated (lost to the surroundings) as?heat

The constant cycling of ATP and ADP+Pi?within a cell