The origin of Life

Origin of the Solar System Earth is estimated to be ~4.6byo Radiometric dating of rocks & meteors Nebula Hypothesis: Nebula: cloud of gas & dust in space Gravity pulled much material together (Sun formed) Planets: remaining materials

Ancient Earth Atmosphere contents: Climate: Ammonia, H2O vapor, Methane (CH4), CO2 Climate: Extreme heat due to meteor impacts & volcanic activity Eventually Cooling: Water vapor condensed (oceans formed) Click on picture to play video clip

Organic Molecules 1. Miller- Urey Experiment Hypothesis: Energy from lightning created organic materials from inorganic ingredients Experimental Set-Up: Ammonia, H2O vapor, Methane, CO gases added Electricity added (simulate lightning) Result: Amino Acids & later nucleotides

Murchison Meteorite 2. Meteorite Hypothesis Hypothesis: Amino acids arrived on earth by a meteorite. Murchison Meteorite

Early Cell Formation Lipid membrane hypothesis Liposomes Spheres of lipids Can form around organic molecules Hypothesis: 1st cell membranes?

Early Genetic Material A hypothesis proposes that RNA was the first genetic material. Ribozymes are RNA molecules that catalyze their own replication. DNA needs enzymes to replicate itself.

Eukaryotic cell formation Endosymbiosis is a relationship in which one organism lives within the body of another. Mitochondria and chloroplasts may have developed through endosymbiosis.

Multicellular Life & Biodiversity Evolution of sexual reproduction led to increased diversity/variation. Sexual reproduction may have led to multicellular life.

Review What is a nebula? What does the nebula hypothesis try to explain? What materials/ingredients did Miller & Urey use in their experiment? Why these and not other ingredients? Why was Miller and Urey’s experiment of great importance? How did eukaryotic cells form? How would sexual reproduction lead to diversity and multicellular life?