Biodiversity First test/week of Feb. 14 notes
Biodiversity First test/week of Feb. 14 notes Bio131
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This 5 page Study Guide was uploaded by Graham Notetaker on Saturday February 20, 2016. The Study Guide belongs to Bio131 at Elon University taught by David Vandermast in Spring 2016. Since its upload, it has received 73 views. For similar materials see Biodiversity in Biology at Elon University.
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Date Created: 02/20/16
Notes for the week of Feb. 14th and Test Prep! Bacteria and Archaea ● Prokaryotes ● Tiny, diverse, ancient, ubiquitous ● Live in virtually every habitat and use diverse and sophisticated types of compounds in cell respiration and fermentation ● Key types: ○ photosynthetic bacteria were responsible for oxygenating the atmosphere, ○ they decompose, cycling nutrients through environments ● Bacteria and archaea form the two biggest (of 3) branches on the tree of life ● You can tell bacteria and archaea apart by: ○ Types of molecules that make up their plasma membranes and cell walls, ○ The machinery they use to transcribe DNA and mRNA into proteins ● Biological Impact: ● Oldest fossils 3.5 bya ● WAY more bacterial cells than your own cells. Medical importance: ● Bacteria that cause diseases for humans are called pathogenic. However, only a tiny fraction are pathogenic Bacteria cause disease ● Robert Koch experimented in late 1800’s, became the basis for the germ theory of disease... Koch’s postulates: 1. Microbe must be present in sick, and not in healthy individuals 2. Organism must be isolated and grown in a pure culture away from host organism 3. If problematic organism from pure culture are injected into healthy subject, they should get sick 4. The organism should be isolated from the diseased experimental animal, again grown in pure culture, and demonstrated again to cause problems Past, Present and Future of antibiotics ● Discovered in 1928 ● Overuse leads to antibiotic resistant strains of bacteria Bacteria Role in Bioremediation ● We pollute our rivers, lakes, and forest ○ Bioremediation is the use of bacteria and archaea to degrade pollutants Extremophiles ● Live in high salt, high temp, low temp, high pressure ● Understanding this may explain how life began ● Astrobiologists use them for info on Extraterrestrial life ● Info on enzymes for use in industrial processes Detecting Bacteria and Archaea ● Enrichment culture ○ Growing them in cultures of growth media to form cultures ● Direct sequencing : new technique for documenting the presence of bacteria and archaea that have never been seen because they cannot be grown in pure culture ○ Specific genes are isolated using PCR, then compared Evaluating Molecular phylogenies ● Carl Woese determined and compared the 16s and 18s RNA molecules for a wide array of species ○ Results came up with the Universal Tree of Life ■ Archaea and eukarya are more closely related than bacteria to either Lateral Gene Transfer: Like sex/fluid exchange for prokaryotes 1. Conjugation (exchange through pilus, or plasma) 2. Transduction (Virus) 3. Transformation (Take up DNA from environment/other dead prokaryotes) Themes: ● Bacteria and archaea show extensive morphological diversity in terms of size, shape, and motility ○ spheres, rods, and chains to spirals ● Cell wall composition: Gram positive (purple) and negative (pink) ○ GP= cell wall with thick layer of peptidoglycan ○ GN= have thin layer of peptidoglycan that won’t retain the stain Metabolic diversity Bacteria and Archaea can get energy from: 1. Light 2. Organic molecules 3. Inorganic molecules Prokaryotic Diversity The ability to : photosynthesis, cellular respiration, and fermentation came from these lineages Nitrogen fixation ● All organisms require nitrogen, but some can’t use it directly ● All eukaryotes and many bacteria and archaea must obtain their Nitrogen in a form such as ammonia or nitrate ● Natural Nitrogen fixation ○ Biological fixation (98%) ○ Lightning strike (2%) ● Haber process (fertilizer) ○ Natural=100 terragrams ○ Haber (fertilizer)=140 terragrams ● Only certain organisms can fix it themselves ○ cyanobacteria ● Some species use Nitrogen as the final electron acceptor Extra vocab for some bacterias... cyanobacteria: (precursor to chloroplasts) alphaproteobacteria: find out what it is (precursor to mitochondria) Some form colonies which can produce a structure called a fruiting body... emphasis on disease this causes (ulcer) Extra credit question: H. pylori is present in ulcers facultative anaerobes: an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent Rhizobial bacteria: (root, microbe) relationship with plants...they fix nitrogen for plant Bacteria: ● Monophyletic group, at least 16 lineages ● firmicutes: are gram positive and most are rod shaped or spherical ○ metabolically diverse ○ important components of soil ○ milk, yogurt, ● Spirochetes ○ Corkscrew shape (spirilla), flagella ○ Cause syphilis and lyme disease ○ Common in aquatic environments ● Actinobacteria are gram positive ○ Have branching filaments called mycelia ○ Many species are heterotrophs, some are decomposers, some live with roots and fix nitrogen ○ Tuberculosis and leprosy are caused by members of this group ● Chlamydiae ○ Spherical and very tiny ○ Endosymbionts (parasites inside animal cells ○ causes blindness ● Cyanobacteria ○ bluegreen algae ○ oxygenic photosynthesis, (produce oxygen and nitrogen and other organic molecules that feed other organisms ○ some have Nitrogen fixing cells called heterocysts Archaea: ● They live EVERYWHERE (Extremophiles) ● 2 major lineages ○ Crenarchaeota: can have any shape. These are extremophiles ○ Euryarchaeota: live everywhere...includes methanogens which contribute to about 2 billion tons of methane to atmosphere each year
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