BIO 112 Study Guide - Midterm Guide: Last Universal Common Ancestor, Eukaryote, Dna Replication
Document Summary
Early atmosphere was very different than today (2/20) Much more methane and ammonia, high levels of co2 and no o2. One of the first mass extinctions on planet. Based on studying rocks from billions of years ago with red bands that show oxidation of iron. Ecological crisis because it was toxic to anaerobic organisms living then. Created uv shield (the ozone layer) with extra oxygen that was produced. Absorbed significant amount of uv radiation that passed through atmosphere. Without it, uv radiation would cause too much mutation. Increases in temperature are higher than those observed in past. Earliest record of life is 3. 7 billion years ago. Looked at reconstructions of atmosphere and determined that early atmosphere was very different. See if they could construct molecules from early atmospheric conditions. Can form bonds with many other elements. Can form double and triple bonds (better for storing energy and catalysis) Universal common ancestor has features between all three domains.
