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Lecture 2: (by Jack Szostak) What is life? Life as a chemical system

Lecture 2: (by Jack Szostak) What is life? Life as a chemical system. Earth life - basic biochemistry Inheritance Enzymes and metabolism Energy. Life’s machinery in a cell. A bacterial cell: RNA molecules transcribe messages from DNA

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Lecture 2: (by Jack Szostak) What is life? Life as a chemical system

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  1. Lecture 2: (by Jack Szostak) What is life?Life as a chemical system Earth life - basic biochemistry Inheritance Enzymes and metabolism Energy

  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.

  3. Structure of DNA

  4. 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.

  5. Organizational Complexity of Modern Life DNA replication RNA processing proteins processing Structure and function

  6. An earlier, simpler time: RNA biochemical functions

  7. Between non-life and life… Viruses Protocells Self-replicating nucleic acids

  8. What do we know about the Origin of Life? From G.F. Joyce, 2002, Nature 418: 214-221

  9. From Chemistry to Biology? small molecules (CO, H2, H20, NH3, CH4…) + energy cofactors lipids + sugars + nucleobases + high-energy + amino acids compounds activated nucleotides peptides Self-assembly into vesicles Assembly into genetic polymer protocell?

  10. Model of Simple Protocell Matter and Energy Fluxes The simplest protocell requires a membrane for compartmentalization, a replicating genome, and a source of nucleotides and lipids. Mechanical energy (for division), chemical energy (for nucleotide activation), and possibly osmotic gradient energy (for growth) may be used by the system.

  11. The RNA World: Pre-biotic RNA formation Janet Iwasa/ Szostak Lab

  12. The RNA World: Formation of Vesicles Janet Iwasa/ Szostak Lab

  13. Why life needs a membrane compartment Janet Iwasa/ Szostak Lab

  14. The RNA World: Protocell life cycle & division Janet Iwasa/ Szostak Lab

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

  16. 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 evolves by natural selection and inheritance of variation 5. life evolves to be adaptive, self-optimizing, fed back, forward; stable to perturbations; 6. Earth life uses molecules that are suited to water.

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