Monophyletic Group a group of organisms that are all more closely related to

Monophyletic group a group of organisms that are all

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-Monophyletic Group = a group of organisms that are all more closely related to each other than they are to any other organisms or group of organisms in any other lineage Lectures 2 & 3 Microorganisms = all forms of life that are generally too small to be seen with the naked eye -Very diverse group – includes bacteria, archaea, most fungi, most protists, and viruses *Viruses are NOT living, they are just microscopic -Most organisms on earth are microbial. Estimates of total biomass on earth suggest that the majority of the biomass on earth is microbial as well General Features of Bacteria -Unicellular (but some are colonial or multicellular) -Microscopic size of individual organism -Prokaryotic cell structure -Most divide by binary fission -Reproduction is asexual (via binary fission) – although gene exchange is common -Tremendous metabolic diversity -An important cause of disease in animals and plants -Also important in biotechnology 2
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Major Bacterial Lineages -Proteobacteria Largest and most diverse “Protean” = “able to do many different things; versatile” Gram-Negative cell structure Contain many disease-causing species (pathogens) i.e. Bdellovibrio bacteriovorans – a predator of other bacteria; has a flagellum that it uses to swim and enter prey’s cell; E.Coli; Akkermansia muciniphila – inhabitant of the animal GI tract (colon); it is a specialist in mucus degredation so it lives off of the mucus in our digestive tract – possibly a mutualist -Firmicutes “Firmicutes” = “thick skin” – because they often have thick cell walls Distinctive groups include: Endospore Formers = production of endospores is a distinctive trait Endospore – a resting stage of a cell, formed inside of a vegetative cell Mollicutes = do not have a cell wall; do not stain Gram-Postive; have sterols in their cell membranes to make them more durable Gram-Positive cell structure Important in medicine, agriculture, and biotechnology i.e. Clostridium botulinum – produces botulinum toxin which prevents activation of muscle cells (interferes with neuron/muscle communication so it inhibits muscle movement) and causes botulism, also botox -Cyanobacteria Are all oxygenic photoautotrophic bacteria Widespread in many aquatic habitats Contribute to primary production (CO 2 fixing); they are the first oxygen-evolving organisms therefore they are responsible primarily for the evolution of our oxygenic atmosphere Gram-Negative cell structure -Actinobacteria Tend to be aerobes Grow as filamentous cells that look a lot like filamentous fungi Gram-Positive cell structure i.e. Streptomyces coelicolor & Streptomyces griseus – both are antibiotic-producing bacteria -Spirochetes Have a distinctive helical cell morphology Most well known for the ability of some species to cause significant human disease Gram-Negative cell structure -Chlamydia Obligate intracellular parasites As a group they can cause infections in most animals and sometimes in humans Gram-Negative cell structure, but they appear to lack peptidoglycan -Bacteroidetes
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