BIOL 226 Lecture 7: Prokaryotes & Eukaryotes
7 Feb 2017
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First life: prokaryotes: only life for 2 billion years. Fundamental division of life: traditional: prokaryotes vs. eukaryotes, cladist: bacteria vs. all else. 3 factors contribute to this genetic diversity: rapid reproduction, mutation, genetic recombination. 3 most common shapes: spheres (cocci, rods (bacilli, spirals. All forms evolved within prokaryotes, nothing new since then. Photoautotrophs: obtain carbon from carbon dioxide and energy from light. Chemoautotrophs: obtain carbon from carbon dioxide, but obtain energy from chemicals consumed in their environments. Photoheterotrophs: obtain carbon from organic molecules and energy from light. Chemoheterotrophs: obtain carbon from organic molecules and energy from chemicals. Obligates aerobes; requires o2 for cellular respiration. Prokaryotes can metabolize nitrogen in a wide variety of ways. In nitrogen fixation, some prokaryotes convert atmospheric nitrogen (n2) to ammonia (nh3) Until the late 20th century, systematics based prokaryotic taxonomy on: shape, motility, nutritional mode, gram staining. Applying molecular systematics has produced dramatic results. Share certain traits with bacteria and other traits with eukaryotes.
