At the molecular level, the heat comes from the agitation of the molecules and therefore their atoms. This increase in agitation causes the molecules to be less condensed between them and will separate after breaks in the intermlecular bonds. This distends the material, as we see when we heat a metal, or a transformation of the phase of the material, such as melting ice or boiling water.
Amino acid reactions. Amino acids via their various chemical functionalities can undergo numerous chemical reactions.
Living organisms use two major types of energy storage. Energy-rich molecules such as glycogen and triglycerides store energy in the form of covalent chemical bonds. Cells synthesize such molecules and store them for later release of the energy.
