Lecture 4 Bild - Lecture 7 Lifes First Billion Years July 7...

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Lecture 7, Life’s First Billion Years - July 7, 2010 EXPLORING BIODIVERSITY SIX LECTURES BACTERIA ARCHAEA 2 billion years of only prokaryotes 4 billion years of successful life at the left wall of minimal complexity EUKARYA ENDOSYMBIOSIS FORMER PROTISTS CAMBRIAN EXPLOSION Nuclear membrane BACTERIA ARCHAEA Membrane-enclosed 2 billion years of only organelles prokaryotes 4 billion years of successful Peptidoglycan in life at the left wall of cell wall minimal complexity THREE DOMAINS: Campbell p. 552: Eukarya, Bacteria, Archaea 3.0 – 3.5 BILLION YEAR OLD BACTERIA, CYANOBACTERIA (see diagram p 517, 553) ORIGIN OF ORGANELLES BY ENDOSYMBIOSIS -SOME PROKARYOTES & ALL EUKARYOTES ARE COMPOSITE ORGANISMS INVASIONS MITOCHONDRIAL 2.0 BYA “spirochaete” FLAGELLUM 1.5 BYA PLASTIDS 1.4 BYA HORIZONTAL GENE TRANSFER STASIS PROKARYOTE SHAPES – spherical, rod shaped, spiral BACTERIAL FLAGELLUM MOTOR NATURE EVOLVES THE WHEEL BACTERIAL CELL-WALL COMPOSITION: PEPTIDOGLYCAN -with 1 or 2 plasma membranes -Gram stain positive or negative (aerobic prokaryote, photosynthetic prokaryote digram) -Infolding of external plasma membrane to produce internal membranes for respiration or photosynthesis Concept 27.3: Extraordinarily diverse nutritional and metabolic adaptations have evolved in prokaryotes • Phototrophs obtain energy from light • Chemotrophs obtain energy from chemicals
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• Autotrophs require CO2 as a carbon source • Heterotrophs require an organic nutrient to make organic compounds • These factors can be combined to give the four major modes of nutrition: photoautotrophy, chemoautotrophy (including lithoautotrophy), photoheterotrophy, and chemoheterotrophy REPRODUCTION BY SIMPLE FISSION: Prokaryotes reproduce quickly by binary fission and can divide every 1–3 hour •Many prokaryotes form metabolically inactive endospores, which can remain viable in harsh conditions for centuries •Anthrax, Clostridium Domain Bacteria PROTEOBACTERIA: 5 diverse groups (alpha-epsilon) Chlamydias Spirochetes Cyanobacteria Gram-Positive Bacteria Proteobacteria Alpha: RHIZOBIUM, -ROOT SYMBIONT OF LEGUMES RESPONSIBLE FOR NITROGEN FIXATION. Beta Nitrosomonas: nitrogen fixation in soil and water Delta Bdellovibrio: spears other bacteria at the equivalent of 600 km/hr Gamma Legionella , Salmonella, Vibrio (Cholera, marine) , Escherichia coli (gut symbiont) -Epsilon Helicobacter ; cause of stomach ulcers Diagram: Two species of Oscillatoria, filamentous cyanobacteria (LM) Streptomyces, the source of many antibiotics (colorized SEM) -Hundreds of mycoplasmas covering a human fibroblast cell (colorized SEM) CHLAMYDIAS: MOST COMMON CAUSE OF BLINDNESS GLOBALLY. MOST COMMON STD IN U.S. SPIROCHETES:
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Lecture 4 Bild - Lecture 7 Lifes First Billion Years July 7...

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