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UGA BIOL 1108 - Bacteria Species

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BIOL 1108 1nd Edition Lecture 4 Outline of Last Lecture I. In the NewsII. Gene Duplication and Divergence A. GeneticsB. HemoglobinC. Types: Subfunctionalization, Pseudogenes, and NeofunctionalizationIII. Do monotremes and marsupials have the genes for fetal hemoglobin?IV. ExtinctionA. CausesB. Mass ExtinctionV. EvolutionA. Macro vs. MicroB. SpeciesC. Types of SpeciationOutline of Current Lecture I. Learning objectivesII. SpeciationA. AllopatricB. SympatricIII. Bacterial SpeciesA. ClassifyThese 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.B. GeneticsC. DefinitionIV. Richard Lenki’s ExperimentCurrent LectureI. Learning objectives- What is the textbook definition of a “biological species” and how might this species definition differ for a microbiologist?- What are the qualities of prokaryotes that make them difficult (impossible) tofit within the classic “biological species” concept?- Give examples of allopatric and sympatric speciation and describe the differences. Be able to interpret a speciation event and to characterize it in terms of allopatry and sympatry. - What is the significance of Rich Lenski’s work?- How does gradualism differ from punctuated equilibrium?II. SpeciationA. Allopatric: A physical geographic barrier that prevents interbreeding and leads to genetic isolation.- To create different species: genetic diversity, environmental changes, and time to evolveB. Sympatric: Genetic isolation occurs within a population despite the lack of a physical barrier.- Ex. Cichlid fish in Lake Victoria- Specialize in niche (food, reproduction, ect.)- Overtime III. Bacterial Species- Bacteria do not undergo meiotic sexA. Classify1. Appearance2. Physiology3. Habitat4. GeneticsB. Genetics- Bacterial “species” are defined by how tightly their hybridized DNA holds together.- If DNA of both species are similar, then the amount of heat to break down the hybridized DNA is less.C. Definition- “a prokaryotic species is considered to be a group of strains that are characterized by a certain degree of phenotypic consistency, showing 70% ofDNA–DNA binding and over 97% of 16S ribosomal RNA (rRNA) gene-sequence identity”IV. Richard Lenki’s Experiment- The E. coli long-term evolution experiment was begun in 1988- A dozen identical populations of asexual bacteria were grown, collected, and evaluated for accumulated differences.- Cultures in a minimal growth medium (low glucose) but with an excess of citrate. - Since E. coli cannot transport citrate across its membrane it cannot use this carbohydrate as an energy source. - Cultures were placed in cryogenic preservation from which they could be thawed and regrown decades later.- Isolated a naturally occurring population that was able to metabolize citrate (Cit+).- Results from previous mutations that pre-disposed the Cit+ strain to evolve. This is referred to as “Historical Contingency”- New


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