Chapter 26 Notes Prokaryotes I Learning Objectives A Describe the basic differences between prokaryotes and eukaryotes B Describe the nitrogen cycle and the essential roles played by prokaryotes C Describe the diversity of prokaryotic metabolic strategies I terms of obtaining carbon energy and oxygen requirements D Outline the phylogeny of the major groups of prokaryotes E Describe how prokaryotes impact human health II Prokaryotes A Small B Abundant in all habitats C Metabolically diverse D Essential to all life on Earth E Huge impact on human health F Basic structure 1 Plasma Membrane 2 Cytoplasm 3 Chromosomal DNA a Circular chromosomes 4 Cell Wall 5 Flagellum b Bacteria often have small circles of additional DNA call plasmids a Helps the prokaryote move this makes them structurally different from eukaryotes 6 Ribosomes III Gram Stains A A positive gram stains means the cell stained well B A negative gram stain means the cell stained poorly C Usually gram negative cells have an additional cell well that block the absorption of the stain IV Reproduction A Prokaryotes reproduce asexually B Genetic diversity arises from mutation C Mutation occurs in three ways 1 Conjugation DNA usually plasmids forms a donor cell and is transferred through a pilus into the recipient cell 2 Transformation DNA is released into the environment by a dead cell and is taken up by a recipient cell 3 Transduction DNA is transferred from a donor cell to a recipient cell by a virus V Prokaryotic Metabolism VI Oxygenic vs Anoxygeneic A Oxygenic Photosynthesis A Prokaryotes are able to use sources of energy not available to Eukaryotes B Prokaryotes species vary in their need and tolerance of O2 6CO2 6H2O C6H12O6 6O2 B Anoxygeneic Photosynthesis 6CO2 12H2S C6H12O6 6H2O 12S C Anaerobic Respiration Organic Carbon 3SO4 6CO2 3H2S 6H2O D Aerobic Respiration Organic Carbon 6O2 6CO2 6H2O VII Prokaryotes and Their Importance to Biology A Prokaryotes play important roles in all the major biochemical cycles B They are essential for sulfur and nitrogen cycles C Only bacteria can fixate nitrogen into useable forms such as nitrate and ammonia D Many prokaryotes have not been grown in cultures E They are only known from their DNA sequences F Common groups of Bacteria 1 Firmicutes 2 Actinobacteria 3 Y protobacteria 4 Cyanobacteria VIII Cyanobacteria A Photosynthetic B They can be single cell or multi cell C They form common green substances like pond scum D They have thylakoid membranes IX Actinobacteria A Many are the source of our antibiotics B They form chain or filament structure C Most actinobacertia are soil dwelling X Firmicutes A They form very dangerous bacteria B They are gram positive and spoor forming XI Protobacteria A These form the largest bacterial clade B They are gram negative XII Great Oxygenation A Cyanobacteria are responsible for the Great Oxygenation B It occurred about 2 5 billion years ago C Fossil stromatolites are trace fossils showing that cyanobacteria began the Great Oxygenation D These fossils show rusted iron which came from oxygen produced by cyanobacteria XIII Bacterial Microfossils A Bacteria impacted earth s oxygen evolution B Oxygen formations were a result of co evolution between prokaryotes and eukaryotes XIV Effects of Prokaryotes on Human Health A Bacteria can help you digest more compounds from your food B Co evolution of prokaryotes and humans has caused interesting cause and effect relationships 1 Observations Obesity in humans is associated with gut micro bacteria that have high firmicute bacteria 2 There are multiple hypotheses for this relationship between obesity 3 If two subjects have the same diet the bacteria in their gut can make C The bacteria in our gut actually help us digest foods that we cannot easily and bacteria the obese digest ourselves D Some species are more efficient at this process E They can process molecules that are links to increase obesity insulin resistance or heart disease
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