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UVM BCOR 012 - Bacteria and Archaeabacteria Introduction

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BCOR 12 1st Edition Lecture 10Outline of Last Lecture I. Protocells and Life Form AbilitiesII. Geological Record of Earth’s HistoryIII. Some Key Event’s in Life’s HistoryIV. Photosynthesis & the Oxygen RevolutionV. Endosymbiont TheoryOutline of Current Lecture I. BiodiversityII. Prokaryote AbilitiesIII. Prokaryote ReproductionIV. Common Characteristics of ProkaryotesV. Factors that cause high genetic variability in prokaryotesCurrent Lecture- Biodiversity – the variety of living organisms in the biosphere (includes all ecosystems) orin a particular habitat or ecosystemo Biodiversity can be analyzed in a small sense (habitat) or in a large sense (biosphere)- Prokaryotes were the first living organisms on Earth and have gone through about 4 billion years of evolutiono They are the most abundant type of organism on the planetProkaryote Abilities- Amazingly efficient- Reproduce at rapid rates (a whole new generation can be developed in 20 minutes!)- Archaeabactera = “extremophiles”o Live in a variety of environments that are considered inhabitableo Ex. Areas of very high pH or very low pH, extreme high and low temperatures, etc.- Bacteria = true bacteria (what we’re more familiar with)- Prokaryotes have the unique ability to withstand a broad range of habitatso Ex. The human gut, the tundra, the deep-sea vents, etc.Prokaryote Reproduction- Prokaryotes have a huge genetic diversity BUT they produce by means on binary fissionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Binary fission – a method of asexual reproduction by division in halfo Genome has to be fully replicated before prokaryotes can split- Asexual reproduction – reproduction without gametes, meiosis, or mitosis involved- Bacterial chromosomes – circular chromosomeso Most bacteria only have one chromosome- Bacteria grow at an exponential rate- Major evolutionary forces that can increase the fitness of bacterial individuals in a stressful environment would be mutation and natural selectiono Mutation causes an advantage of one bacteria and natural selection selects for that mutation so it gradually becomes a large part of the gene pool- Mutations are rarely passed on in multicellular organismsCommon Characteristics of Prokaryotes- All bacteria are unicellular - Bacteria often live in colonies- They come in three shapes:o Sphericalo Rod-shapedo Spiral- Fimibrae – a short, hair-like appendage that helps a prokaryote adhere to a substrate or another cell- Bacterial capsule – a sticky layer that surrounds the cell wall of some prokaryotes. It provides:o Protectiono Adhering to cell surface- Plasmid – an independently replicating DNA molecule and carries only a few genes that are usually not essential to the bacteria’s survival but are helpfulo Plasmids are used a lot in laboratories for transferring genes between organisms- ALL BACTERIA HAVE A CELL WALL- Genetic recombination – when we get a new combination of alleles- Remember, mutations are a source of new genetic material- Bacteria undergo genetic recombination in absence of sexual reproduction through the use of horizontal gene transfer – the transfer of genes between living organisms of the same generation- A mutation does not involve combination of genes Factors that cause High Genetic Variation in BacteriaI. Rapid ReproductionII. MutationIII. Genetic recombination via horizontal gene transfera. Transformation – the taking up of foreign DNA by a bacteria b. Transduction – involves a virus transferring DNA from one bacteria to anotherc. Conjugation – direct contact between bacteria is made and genes can be transferred - Not all bacteria can do all the forms of genetic recombinationo Transformation and conjugation have special genes that allow them to do the actions- Bacteria are characterized by their nutritional modes and metabolic adaptations that have evolved in prokaryotes - Nutrition modes:o Autotrophs – obtain necessary energy to fuel the work of the cell from light (photo-) or chemicals when light is not available (chemo-)- ONLY prokaryotes can be chemoautotrophs- Their energy sources are inorganic compoundso Heterotrophs– require at least one organic nutrient (ex. Glucose) to make another compound (proteins, lipids, etc.)- Photoheterotrophs are unique to prokaryotes- Chemoheterotrophs are like humans where they eat to fuel


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