BIOL 242 Study Guide - Midterm Guide: Horizontal Gene Transfer, Multicellular Organism, Facultative Anaerobic Organism
Document Summary
First solid evidence of life dated- 3. 5 billion years ago. Geological changes- changes in rocks and layering. Continental changes- continental drift, at 250 million years ago continents were all connected, 130 million years ago there were 2 continents, and 65 million years ago we had all continents. Atmospheric changes- the atmosphere of the earth was originally reducing (it had no oxygen), it then became oxidizing (has oxygen) First cells, formed at 3. 5 billion years ago, were prokaryotic meaning they have no nucleus or organelles. Metabolic pathways had to develop to be able to create the 4 major molecules of life: carbs, proteins, fats/ lipids, nucleic acid. Rna came first and set the pathway for dna and proteins, atp is another derivative of rna. Glycolysis required atp but does not need oxygen. Oxygen is a byproduct of photosynthesis so it began to be released into the atmosphere at high rates, this happened about 2. 5 billion years ago.
