BIOL 150 Lecture Notes - Lecture 17: Spirochaete, Nuclear Membrane, Firmicutes
Document Summary
~4 billion years ago the crust solidified. ~3. 5 billion years ago we find the oldest fossils of microorganisms. Prokaryotes dominant between 3. 5 to 2 billion years ago. Three domains of life: two cell types: prokaryotes, bacteria (3. 5 bya, archaea (1. 75 bya, eukaryotes, eukarya (1. 75 bya, eukaryotic cells- protists, plants, fungi, and animals. Two types: thick peptidoglycan: called gram + (positive, thin peptidoglycan with outer membrane: gram - (negative); these are more resistant to antibiotics because of extra membrane. Anaerobic (can survive in absence of oxygen) Diversity arises from mutations passed down to new cell copies (vertical gene transfer) and bacterial recombination (horizontal gene transfer. No free oxygen until cyanobacteria lived 2. 7 bya. Internal membranes for photosynthesis; origin of eukaryotic chloroplast. Uses n2 to make nh3 (nitrogen cycle) Pathogens are any organisms that can cause disease (type of consumption) Less than 1 percent of bacteria are pathogenic.
