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Microbiology: Classification and Identification of Microorganisms

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  • What is taxonomy in microbiology?

    Taxonomy is the science of classifying organisms, showing the degree of similarity among them.

  • Define systematics or phylogeny.

    Systematics, or phylogeny, is the study of the evolutionary history of organisms.

  • Who developed the three-domain system and on what basis?

    Woese developed the three-domain system in 1978 based on sequences of nucleotides in rRNA.

  • Name the three domains of life.

    The three domains are Bacteria, Archaea, and Eukarya.

  • What are key characteristics of Archaea compared to Bacteria?

    Archaea have unique membrane lipids, no peptidoglycan in cell walls, and include methanogens and extremophiles, differing from bacteria.

  • What is the significance of endosymbiotic bacteria in eukaryotic evolution?

    Endosymbiotic bacteria developed into organelles like mitochondria and chloroplasts in eukaryotes.

  • What is binomial nomenclature?

    Binomial nomenclature uses a two-part name: genus and specific epithet to consistently name organisms worldwide.

  • Define a prokaryotic species.

    A prokaryotic species is a population of cells with similar characteristics.

  • Differentiate culture, clone, and strain in microbiology.

    Culture: bacteria grown in lab media; Clone: cells from a single parent; Strain: genetically different cells within a clone.

  • What kingdoms are included in the domain Eukarya?

    Eukarya includes kingdoms Fungi, Plantae, Animalia, and Protista.

  • Why are viruses not classified in any domain?

    Viruses are not composed of cells and require a host cell, so they are not part of any domain.

  • What is Bergey’s Manual used for?

    Bergey’s Manual provides identification schemes for bacteria and archaea.

  • How are biochemical tests used in bacterial identification?

    Biochemical tests detect bacterial enzymes to differentiate species based on metabolic characteristics.

  • What is the principle of the slide agglutination test?

    Bacteria agglutinate when mixed with specific antibodies, indicating antigen-antibody reaction.

  • Describe the ELISA test in microbiology.

    ELISA uses enzyme-linked antibodies to detect antigens, producing a visible color change to identify bacteria.

  • What does Western blotting detect?

    Western blotting identifies antibodies in patient serum to confirm infections like HIV and Lyme disease.

  • Explain phage typing.

    Phage typing determines which bacteriophages infect and lyse a bacterial strain, shown by clear plaques on a plate.

  • What is DNA fingerprinting in microbial classification?

    DNA fingerprinting uses electrophoresis of restriction enzyme-digested DNA to compare genetic similarities.

  • What does nucleic acid hybridization measure?

    It measures the ability of DNA strands from different organisms to hybridize; >70% hybridization indicates the same species.

  • What is the function of a DNA chip (microarray) in microbiology?

    A DNA chip contains probes that detect pathogens by hybridization with sample DNA, detected by fluorescence.

  • What is a cladogram?

    A cladogram is a map showing evolutionary relationships among organisms based on rRNA sequences.