Chapter 15 Evolution of Microbial Life

Chapter 15 Evolution of Microbial Life - Chapter 15-...

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Chapter 15- Evolution of Microbial Life 1. Overview of History of Life a. See posting on website and learn sequential order of events listed [15.2] 2. Prokaryotes a. Earliest form of life: fossils 2.5 billion years before present i. Prokaryote structure and Function 1. No nuclear envelope, no membrane-bound organelles [4.4,4.5] 2. Three Shapes: [15.10] a. Rods (bacilli) b. Spheres (cocci) c. Helical (spirochetes) 3. Almost all are unicellular a. But some form simple colonies [15.1] 4. Many are mobile, with flagella a. But not same as in eukaryotes [15.11] ii. Domain Bacteria 1. Most abundant organisms on earth a. Reproduce rapidly by binary fission (asexual) 2. Many can survive harsh conditions by forming into resistant endospores a. Ex: bacteria that cause anthrax, botulinism 3. Bacteria nutritional diversity: a. Most are absorptive heterotrophs i. Absorptive- dissolved materials pass thru plasma membrane ii. Heterotrophic- uses organic matter as both carbon and energy source iii. Some are anaerobic (=must have no oxygen) iv. Some do aerobic cellular respiration just like mitochondria (require oO2)
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b. Many are photoautotrophs- use CO2 as carbon source and light as an energy source i. Cyanobacteria do photosynthesis just like plants 1. Make huge % of earth’s O2 today 2. Original source of O2 in air in history of earth 4. Bacteria and Symbiosis- two species living in close relationship
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Chapter 15 Evolution of Microbial Life - Chapter 15-...

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