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Chapter 26

Chapter 26 - Chapter 26 Bacteria and Archaea The...

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Chapter 26: Bacteria and Archaea: The prokaryotic Domains 26.1 – How did the living world begin to diversify? o Eukarya, bacteria and archaea all: Conduct glycolysis Use DNA to encode proteins Produce those proteins via transcription and translation Replicate DNA semi conservatively Have an abundance of plasma membranes and ribosomes o Prokaryotes differ from eukaryotes in 3 important ways: Prokaryotic cells lack a cytoskeleton and a nucleus Prokaryotes divide by binary fission Organization of genetic material differs Prokaryotes usually have disorganized DNA or plasmid circles Prokaryotes have none of the membrane enclosed cytoplasmic organelles (e.g. mitochondria, Golgi apparatuses, etc…)that are found in eukaryotes o Archaea are both alike and different from eukarya and bacteria o The basic structure of both a bacterium and an archaeon is the prokaryotic cell In addition, they have DNA, RNA, enzymes for transcription/translation and a system to generate ATP o Eukarya more in common with archaea than bacteria o Eukaryotic mitochondria came from the endosymbiosis of a bacterium Such that eukarya could be a fusion of bacteria and archaea o some genes of eukaryotes are closer to bacteria, others are closer to archaea this means the tree of life has some merging of its lineages o original ancestor probably had circular chromosome o bacteria come in 3 shapes
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spheres – coccus/cocci rods – bacillus/bacilli curved/helical – helix/helices o less is known about the morphology of archaea, but they do come in cocci, bacilli, triangular, square shaped o none of them are primitive 26.2 – What are some keys to the success of prokaryotes? o Prokaryotes have the highest number of individuals in the world o Prokaryotes are unicellular organisms, although many form multicellular colonies o Prokaryotes associate in chains because after binary fission, they sometimes wont separate, this leads to long chains called filaments Some filaments become enclosed in tubular sheets o Prokaryotes can create dense biofilms, which secrete a gel-like sticks polysaccharide matrix that then traps other cells o In monitoring biofilm development, scientists found a unique use of microfluidics. o Microfluidics use microscopic tubes and computer controlled valves to plumbing circuits in growth chambers o Many prokaryotes have thick, stiff cell walls They contain peptidoglycan – which produces a mesh like structure o Peptidoglycan is a substance unique to bacteria; its absence from the walls of archaea
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Chapter 26 - Chapter 26 Bacteria and Archaea The...

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