1. 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

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

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

4. 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.

5. 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

6. 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