Summary:
- Living organisms need chemical reactions to live, grow, and reproduce.
- The chemical reactions occur in sequences of steps known as metabolic pathways.
- The metabolic pathways are very similar for all life on Earth.
- This means that the metabolic pathways evolved very early in Earth's history.
- Some scientists think that RNA was the first replicating molecule.
- Every organism has a collection of genes that code for the traits that organism could have.
- Not all genes are expressed; therefore, knowing all of your genes does not tell you exactly who you are.