Bacteria and Archaea 03 19 2014 Approximately 10 trillion cells in human body 10 bacteria archaea cells to every human cell In total volume bact archaea cells are dominant Biological Impact Abundant Live in diverse habitats o Found almost everywhere and anywhere o Some thrive in extreme environments extremophiles High salt high temp high pressure habitats Can help with understanding the origin of life Predicted that the First life forms lived in these environments Commercial applications since their enzymes work in extreme conditions they can be used in research Medical importance o Only a fraction of the thousands of bacterial species in your body can disrupt bodily functions enough to cause illness These disease causing bacteria are pathogenic Tend to affect tissues at the entry points to the Koch s postulates body Hypothesized that bacteria was responsible for infectious diseases o Tested the hypothesis by seeing what caused anthrax Four criteria had to be met o 1 microbe present in infected absent in healthy ppl o 2 organism must be isolated and grown in pure culture o 3 if injected into a healthy person symptoms should appear o 4 organism should be isolated again and should be the same Some things don t always work o Can t grow every bacteria in culture The Germ Theory of disease Certain diseases are infectious and can be passed ppl to ppl Bacteria and viruses can be passed by transmission and grown Laid the foundation for modern medicine o Greatest impact initially was on influencing sanitization Pathogenic bacterial cells Virulence the ability to cause disease o Heritable trait that varies among individuals in a population o Genomes of some cells in the same species are larger than others because the pathogenic cells have acquired virulence genes making them able to cause a disease Toxin proteins are coded by virulence genes They inhibit protein synthesis by ribosomes Antibiotics past present and future molecules that kill bacteria Produced naturally by soil dwelling bacteria and fungi Antibiotics in soil are predicted to help cells reduce competition for nutrients and resources At first gave doctors effect weapons against bacterial infections Now many bacteria are now drug resistant some even eat antibiotics o Another advantage of bacteria biofilms Dense colonies covered by a polysaccharide rich matrix that protects bacteria from antibiotics Role in Bioremediation cleaning up sites polluted with organic solvents Archaea and bacteria can be helpful in this technique o They can grow in the spills and degrade the toxins Can be enhanced by two complementary bioremediation strategies Fertilized the sites to encourage growth of bacteria Seeding or adding specific bacteria to sites How we study Bacteria Archaea Enrichment Cultures technique to isolate new types o Establish certain growing conditions and seeing which cells thrive in these conditions o Create an abundant amount of bacteria sample to study farther Metagenomics analysis that allows biologists to quickly identify organisms that have never been seen before Extract and sequence the DNA from a sample and identify species biochemical pathways by comparing to known genes Phylogenetic Trees use of small subunits of RNA found in ribosomes to create these trees 16S and 18S RNA Based on the data from ribosomal RNA molecules the major divisions of life are o Bacteria o Archaea o Eukarya Diversity of bacteria and archaea Morphological diversity o Bacteria only Size bacteria range from smallest of all free living cells Shape range in shape from filaments spheres rods to a billion sizes larger chains and spirals Mobility can move by rotating flagella can either move ahead or tumble gliding also occurs but we don t know how o Cell wall differences b w both Gram staining only for bacteria with cell walls helpful in determining which drugs to use against bacteria purple pink plasma membrane surrounded by cell wall with extensive peptidoglycan plasma membrane with thin peptidoglycan surrounded by phospholipid bilayer on outside Metabolic Diversity chemical rxns that go on inside the cells o Very diverse in the compounds they can use as food o Producing ATP Phototrophs light feeders use light to excite electrons Chemotrophs inorganic or organic materials serve as electron donors and are oxidized o Carbon source Autotrophs organisms that make their own building blocks from simple starting compounds CO2 CH4 self Heterotrophs absorb ready to use organic compounds from their environment acquire from other compounds feeders other feeders o Bacteria archaea can be all different mixes of the above Evolution allowed variations of these mixes to live in diverse habitats VARIATIONS IN METABOLISM Producing ATP through Cellular Respiration Many bacteria and archaea vary in their electron donors and electron acceptors Eukaryotes usually use CO2 to donate and O2 to accept but bact arch Can use other molecules Things with high potential energy are donors low potential energy molecules are electron acceptors Producing ATP through Fermentation No outside electron acceptor is used so it is much less efficient Bacteria and archaea are able to ferment things other than glucose which is usually the starting point for fermentation Producing ATP through Photosynthesis variation in electron sources pigments Phototrophs can perform photosyn In three ways o 1 Chemiosmosis drives synthesis of ATP o 2 Some use radiation instead of light in hydrothermal vents o 3 As electrons are passed from high to low energy states the energy released is used to create ATP Species that use water as their electron source are oxygenic Others that don t use water are called anoxygenic non oxygen oxygen producing producing Many different pigments have been discovered Obtaining building blocks from compounds CARBON Not all use the Calvin cycle to make building block molecules Not all start with CO2 as the source of carbon atoms Bacteria and archaea can use different starting materials and different pathways to create building blocks Global Impacts Oxygen revolution Cyanobacteria were the first to perform oxygenic photosynthesis Aerobic respiration was now a possibility and oxygen could be used as a final electron acceptor A huge increase in concentration of oxygen in the atmosphere occurred Nitrogen fixation and the nitrogen cycle N2 is hard to break and use since it has triple bonds Only some bacteria and archaea can use molecular nitrogen to convert it into ammonia NH3 aka
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