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Chapter 3 Outline3.1Prokaryotes share a common set of characteristics- DNA as hereditary material- Complex biochemical patterns of growth and energy conversions- Complex responses to stimuli- Reproduction to produce offspring- Adaptation from one generation to the next- Interactions with other organisms and the environmentProkaryotes- Lack of visible cell structure- Pattern of organization- Cellular process is over looked. Carry out many of the same cellular processes as Eukaryotic cells- Homeostasis- Antibiotic resistance- Associative learning – cells “learn”- Respond to environmental cues- Possess a sophisticated chemical language- “speak to each other”Biofilms- Associated with infections such as cystic fibrosis- Impervious to most antibiotics- Can develop improperly cleaned medical devices- Not all are harmful- Bioremediation uses microorganisms to help remove or clean up chemically contaminated environmentsBacterial cells undergo “cross talk” through QS and multicellular communities, leading to some form of community behavior when their numbers reach a threshold Eukaryote and Prokaryote SIMILARITIES- 1830s Matthias Schleiden and Theodor Schwann developed part of the cell theory by demonstrating that all plants and animals are composed of one or more cellso About 20 years after Rudolph Virchow added that all cells arise from pre-existing cells- Genetic Organization – all organisms have DNA that is communicated or expressed using an almost universal genetic code- Eukaryotic cells have multiple linear chromosomes enclosed by the membrane envelope of the cell nucleus- Prokaryotic cells have a single, circular DNA molecule w/o an enclosing membrane- Compartmentation – all cells have an organizational pattern separating the internal compartments from the surrounding environment - Plasma membrane in eukaryotes - Metabolic Organization – all cells have an internal environment in which chemical reactions occur and ATP is generated- Protein Synthesis- RibosomesProkaryote- Cell membrane- Cell wall- DNA- Ribosome- CytoplasmEukaryote- Cytoskeleton- Plasma membrane- Lysosome- Cytoplasm- Golgi apparatus- Centrosome- Flagellum- Free ribosomes- Mitochondrion- Nuclear envelope- DNA- Ribosomes attached to endoplasmic reticulum- Cilia- Smooth ER- Rough ER****KNOW FUNCTIONS****Refer to page 73 and 74 table 3.1 for everything prior to this3.2Classification Attempts to Catalog Organisms - 18th century Carolus Linnaeus began identifying living organisms according to similarity in form and placing organisms in one of two “kingdoms: - Vegetalia and Animalia- Mid-1860s Ernst Haeckel identified a fundamental problem in the 2 kingdom system- The unicellular organisms identified by Haeckel, Pasteur, and Koch did not conform to the 2 kingdom system- Haeckel made a 3rd system – Protista. The bacterial organisms- which he called moneres- were near the bottom of the tree- 1937- Edouard Chatton proposed that there was a fundamental dichotomy among the Protista. He saw bacterial cells as having distinctive properties. - 1950s- development of the electron microscope made it apparent that protists had a membraneenclosed nucleus and were identified as being eukaryotes while other protists lacked this structure and were classified as prokaryotes- 1956- Herbert Copland suggested that bacterial organisms be placed in a fourth kingdom , the Monera- Robert H. Whittaker saw the fungi as another kingdom of organisms. The fungi are the only eukaryote group that must externally digest their food prior to absorption and, as such, live in the food source. 1959 he refined the 4 kingdom system to 5. - 1970s Carl Woese – Monera contained two fundamentally unrelated groups- made the bacteria and the ArchaebacteriaKingdoms and Domains- Carl Woese – along w/ George Fox – proposed domains- Woese discovered that the nucleotide sequences in the archaebacteria were different from those in other prokaryotes and eukaryotes - Other differences included: cell wall composition, membrane lipids, and sensitivity to certainantibioticsNomenclature gives scientific names to organisms- Linnaeus – Systema Naturae. Popularized 2 word scheme of nomenclature. The two words usually derive from greek or latin - Each organism’s name consist of the genus to which organisms belong to and a specific epithet. Together these two make up the species name- EX: Eschericia coli Classification uses a hierarchial system - Several similar species are grouped together into a genus - A collection of similar genera makes up a family- Families with similar characteristics make up an order- Different orders may be placed together in a class- Classes are assembled together into a phylum - All phyla would be placed together in a kingdom or domain- David Hendricks Bergey devised one of the first systems of classification for the bacterial speciesin 1923Many Methods Are Available to Identify and Classify Microorganisms- Bergeys Manual of Determinative Bacteriology is the primary source for making medical identifications of bacterial pathogensPhysical Characteristics- Organisms shape- morphologyBiochemical Tests- Fermentation - Use of specific substrate - Refer to page 81,82Nucleic Acid test- Page 83Many Microbial Agents are in the micrometer size range- Microbial agents range in size from the relatively large, almost visible protists to incredibly tiny virusesLight Microscopy Is used to Observe Most Microorganisms - Light Microscope – visible light passes through a condenser lenses and specimen. - Called bright-field microscopy- Focuses the light into a sharp cone- Light then passes through the opening in the stage- When hitting the glass side, the light is then reflected or refracted as it goes through the specimen - Light enters the objective lens to form that of the specimen - Intermediate image becomes the object- Magnified and seen by observer- A light microscope usually has at least 3 objective lenses: lower-power, high-power, and oil immersion lenses- Magnify and object 10,40, and 100 times- The ocular lens then magnifies the intermediate image by 10x- Total magnification is 100x,400x, and 1,000x- Must have good resolution- Switching from low power (10x) to high power (40x) lens to the oil immersion lens (100x) one quickly finds the image becomes fuzzy- The objects lack resolution Staining Techniques Provide Contrast- Cytoplasm usually lacks color- First – smeared on a glass slide and the slide is air dried- The


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LSU BIOL 1011 - Chapter 3 Outline

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