Lecture - Oct 7

Lecture - Oct 7 - Viruses and Prokaryotes (earliest life...

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Viruses and Prokaryotes (earliest life forms) Chapter 24 Conjugation Two cells of different mating types exchange genetic material This F factor (also called F plasmid) contains 20 genes – important in conjugation: Encodes enzymes necessary to transfer DNA and produce the sex pili . Modes of Nutrition: Heterotrophs - Chemoheterotrophs o Free-living decomposers o Obtain carbon and energy from dead organic matter (glucose etc) o Some pathogens, and obtain nourishment from infected host - Photoheterotrophs o Obtain carbon from other organisms o Use photosynthetic pigments to trap light energy Autotrophs: - Photoautothrops o Synthesise organic compounds from CO2 and other inorganic compounds o Obtain energy from sunlight - Chemoautotrophs o Use co2 as carbon source o Obtain energy by oxidizing inorganic chemicals such as NH3 and H2S Aerobes and Anaerobes - Aerobic bacteria o Require oxygen for cellular respiration - Facultative anaerobics o Metabolize anaerobically when necessary - Obligate anaerobes o Only metabolize anaerobically o Killed in low O 2 Hypo/hyperthermia with hypoxia
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3 Domains - Domain Archaea (prokaryotes) o Cell walls do not have peptidoglycan - Domain Bacteria (prokaryotes) o Cell walls have peptidoglycan - Domain Eukarya o Four kingdoms of eukaryotes Table 24-2 NB: FA is a straight chain hydrocarbon with a carboxylic (COOC) grouping at the end (makes an ester linkage to glycerol) Archaea have hydrocarbons with a carbonyl linkage (COC) grouping making an ether linkage to glycerol. Domain Archaea - PM contains branched hydrocarbons (not FA) bonded to glycerol by ether linkages (not ester) – stronger - More like eukaryotes than bacteria in some major areas: o Do not have simple RNA polymerase found in bacteria o Unaffected by some antibiotics that affect bacteria Methanogens - Produce methane from carbon compounds - Inhabit anaerobic environments Extreme halophiles - Inhabit saturated salt solutions - Use aerobic respirators to make ATP - Membrane pigments provide intense color Ectreme thermophiles - Live at temperatures greater than 100* C - Often at pH 1-2 Domain Bacteria - Gram-negative o Proteobacteria
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o Cyanobacteria o Chlamydias o Spirochetes - Gram-positive o Actinomycetes o Mycoplasma Cyanobacterium Many prokaryotes such as the Cyanobacteria, carry out photosynthesis; using water as the electron source and generating O2 while fixing CO2 into organic molecules. Anabaena fixes
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Lecture - Oct 7 - Viruses and Prokaryotes (earliest life...

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