Lecture 1 the molecules of life and biological macromolecules. Differences between living from non-living: complexity with precise spatial organization, ability to respond to the environment, reproduction, evolve (see picture on the side for comparison of the elements of non-living and living) First law of thermodynamics: energy can be neither created or destroyed. It is transformed from one form to another: therefore, the total energy of the universe is constant. Cells are the simplest self-replicating entity that can exist as an independent unit of life. All organisms are made of either a single cell or an ensemble of cells. Life likely originated on earth through a set of chemical reactions that gave rise to the molecules of life. The atom is the fundamental unit of matter. An element is composed of an atom: atom, a dense central nucleus made up of positively charged protons and electrically neutral particles (neutron, negatively charged electrons move around the nucleus.