BIOC 4403 Lecture Notes - Lecture 9: Mobile Genetic Elements, Shotgun Sequencing, Homologous Recombination
27 Mar 2017
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Document Summary
Prokaryotes: cells with co-transcriptional translation on their main chromosomes; they translate nascent rnas into protein. Prokaryotic is controversial because eukaryotes and archaea are more closely related to each other than to bacteria. Hidden microbial majority: easily isolated organisms are the weeds" of the microbial world and are estimated to constitute less than 1% of all microbial species. Microorganisms isolated from standard cultivation methods are rarely numerically dominant in nature. Shotgun sequencing the sea: took samples from the sea, used cloning, shotgun and sanger sequencing to assemble all of the data, discovered thousands of new prokaryotic species. Only 30% of known prokaryotes have a genome project assigned to them. Nucleoid: prokaryote chromosome structure, can be circular, linear, both, or megaplasmid. There is highly uniform gene density for prokaryotes, unlike eukaryotes. Homologous recombination: generates novelty by recombing alleles within a population ( species") Rate of recombination drops exponentially as sequences diverge. Clonal model: novelty comes from mutations arising within asexual populations.
