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Unformatted text preview: BIOL 142: Study Guide for TEST # 2 Chapter 28 Prokaryotes Prokaryotes (bacteria and archaea) are the oldest forms of life: The first cells were prokaryotes and appeared about 3.5 BYA (we know from microfossils , isotopic analysis to determine when carbon fixation began, and lipids created by cyanobacteria = biomarkers ) Prokaryotes are very abundant (there are a lot of them) and are ubiquitous (they are everywhere) Prokaryotes are the simplest forms of life:- they are all unicellular- they are very small (about 10X smaller than eukaryotic cells)- they have a single, circular, double-stranded molecule of DNA in the nucleoid + plasmids (= extrachromosomal fragments of DNA)- they do have ribosomes but do not have any membrane-bound organelles- cell membranes are different in bacteria and archaea (archeaa have branched lipids and can form monolayers)- cell walls of bacteria have peptidoglycan (cell walls of archaea do not) particular structure determines gram + versus gram staining results which corresponds with susceptibility to...
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This note was uploaded on 09/18/2011 for the course BIO 142 taught by Professor Jarrell during the Spring '11 term at Delgado CC.
- Spring '11