ENERGY AND LIVING THINGS Almost all of the energy in living systems needed for metabolism comes directly or indirectly from the sun. Flow of Energy

Metabolism involves either: using light energy to build molecules (photosynthesis) OR (2) breaking down molecules (cellular respiration) in which chemical energy is stored

Energy Storing Molecule ATP – Adenosine Triphosphate a nucleotide with 2 extra energy-storing phosphate groups

The removal of a phosphate group from ATP releases energy producing ADP. ATP ADP + P + energy Cells recycle ADP to make new ATP to store more energy or future use.

I. Building Molecules that Store Energy Photosynthesis – the process by which light energy is converted to chemical energy autotrophs – organisms that use energy from the sunlight to make organic compounds (ex: glucose – a carbohydrate) ex: plants, algae, prokaryotes

II. Breaking Down Molecules for Energy Cellular Respiration – the process by which cells produce chemical energy from carbohydrates; energy is released in food to produce ATP, ATP provides cells with the energy they need to carry out life functions heterotrophs – organisms that get energy from food instead of directly from sunlight ex: animals autotrophs – undergo cellular respiration to release ATP in the carbohydrates they produced