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Lecture 4

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Department
Biological Sciences
Course
BISC 110
Professor
Robin Barrow
Semester
Fall

Description
Lecture 4- Prokaryotes and the evolution of metabolism Chapter 25, pp. 514-516 Chapter 27, pp. 566-567, p. 570 (sections on Archaea and Bacteria only) Chapter 27, Concept 27.3: pp. 564-565 Geological Record •divided into 3 eons •Archaean •Proterozoic •Phanerozoic •Paleozoic •Mesozoic (age of reptiles) •Cenozoic •each boundary between eras represent extinctions and formations Prokaryotes (pro: before, karyos: nucleus) •most ancient unicellular organisms (earth's sole inhabitants) •lived alone on Earth for nearly 2 bya; they created the life on Earth •greatest diversity of lifestyles and habitats •have a high range of metabolic adaptions, more than eukaryotes •their domain: •Bacteria •includes most known prokaryotes •huge diverse metabolism & structure •includes: •photosynthetic cyanobacteria •organisms important in decomposition and nutrient cycles •some disease organisms •peptidoglycan in cell wall •famous bacteria: •borrelia: lyme disease caused by spiral shaped bacteria (ticks) •salmonella: in your food (contamination of raw meats) •Archaea •how they're different from bacteria: •cell wall composition •details of protein synthesis •live in harsh environments; prokaryotes (Extremophiles: 'extreme-lovers') •famous archaea: •methanogens: methane-makers, in guts of animals (use CO2 to oxidize H2, producing energy and methane waste; methanogens are poisoned by O2) •halophiles: salt-lovers •thermophiles: heat-lovers, in smoking vents living 121° (Eukarya: NOT prokaryotes...protists, fungi, plants, animals) Prokaryotes VS Eukaryotes •Prokaryotic cells •smaller with single membrane •nucleoid with no membrane •no nucleus •no walled organelles •no cytoskeleton Modern prokaryotes as clues to evolution of metabolism •some prokaryotes today lived in environments similar to those in early earth •metabolism of modern prokaryotes similar to metabolism of ancient prokaryotes •phototrophs: obtain energy from light •chemotrophs: obtain energy from chemicals •autotrophs: obtain energy from carbon source •heterotrophs: obtains energy from organic nutrient to make other organic compounds •Nutritional mode; NRG + carbon sources used as energy •Photo-autotroph; Light + CO2 •Chemo-autotroph; Inorganic chemicals + CO2 •Photo-heterotroph; Light + Organic compounds •Chemo-heterotroph; Organic compounds •Respiratory mode: •Obligate anaeroby: Fermentation/anaerobic respiration; never uses O2 •Facultative anaeroby: O2 if pres
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