1. Lecture 8: What is life? - Life as a chemical system 1.Earth life - basic biochemistry 2.Metabolism 3.Catalysis 4.Genetics

2. Life’s machinery in a cell A bacterial cell: RNA molecules transcribe messages from DNA that are used to produce protein molecules inside ribosomes - Fig.5.1 - A. Knoll (2003).

3. Structure of DNA & RNA Molecular structure - Fig.5.2 - A. Knoll (2003).

4. Lipid bilayer vesicles in clay RNA (red) adsorbed into clay, inside a vesicle (green) - Szostak lab (2004).

5. Phylogenetic Tree of Life

6. Science, 2006

7. Earth life - main attributes: 1) life is chemical in essence; an ordered network of chemical reactions; 2)life is energy dissipating; out-of-equilibrium system; 3)life is compartmentalized; 4)life is adaptive, self-optimizing, fed back, forward; stable to perturbations; 5)life uses molecules that are suited to water.