​Chemical Energy and ATP

• Stored in chemical compounds

• Breaking and forming chemical bonds releases energy

​Storing Energy

• All living things store energy in chemical bonds of of certain compounds

• ATP (Adenosine Triphosphate) - compound used by cells to store and release energy

  • Composed of adenine, ribose, and 3 phosphate

• ADP (Adenosine Diphosphate)

  • Consists of adenine, ribose, and 2 Phosphates

• Difference between ATP and ADP is how energy is stored

• Add a phosphate to ADP to store energy

​Releasing Energy

• Cells release energy in ATP by the controlled breaking of the chemical bonds between atoms in the second and third phosphate groups

  • energy is used to add a phosphate to ADP

  • energy is released when a phosphate is split off and released

• ATP can release and store energy by breaking and re-forming the bonds between the phosphates

• This characteristic of ATP makes it exceptionally useful as a basic energy source for all cells

How Cells Use ATP

• Cells use energy provided by ATP

  • Active transport

    • 20-40% of energy used by the cell

  • Enable cells to move

    • flagella-cilia- white blood cells

  • Protein synthesis, movement within cells, responding to signals, producing light

HETEROTROPHS AND AUTOTROPHS

• Most animals obtain energy from food - heterotrophs

  • Some eat plants- herbivores

  • Some eat other animals that eat plants - carnivores

  • Some can obtain energy from both - omnivores

  • Some obtain energy from decomposition - fungi

HETEROTROPHS AND AUTOTROPHS

• All energy in food comes from the sun

  • Some organisms use energy from sunlight to make food - autotrophs

    • plants

    • algae

    • some bacteria - cyanobacteria

  • Nearly all life on earth depends on the sun

  • Photosynthesis is the process by which plants convert the energy of the sun into chemical energy stored in the bonds of carbohydrates.