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Introduction to Microbiology

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  • What is microbiology?

    Microbiology is the study of organisms too small to see with the unaided eye.

  • Who first observed microorganisms and how?

    Antoni van Leeuwenhoek first observed microorganisms in the 1600s using high-quality magnifying lenses to create a simple microscope.

  • What are the three domains of life?

    The three domains are Domain Bacteria, Domain Archaea, and Domain Eukarya.

  • What type of cells did van Leeuwenhoek first see?

    He first saw relatively large cells with organelles, now known as eukaryotes in Domain Eukarya.

  • What are examples of eukaryotic microorganisms?

    Examples include photosynthetic algae with chloroplasts, phagocytic protozoa, and fungi that absorb organic matter and have cell walls.

  • What are prokaryotes?

    Prokaryotes are very small cells with no organelles, divided into Domain Archaea and Domain Bacteria based on rRNA differences.

  • What distinguishes Gram-positive bacteria?

    Gram-positive bacteria have a thick peptidoglycan cell wall and are sensitive to antibiotics like penicillin.

  • What distinguishes Gram-negative bacteria?

    Gram-negative bacteria have an outer phospholipid bilayer with an LPS layer containing toxic lipid A, often resistant to penicillin.

  • What are viruses composed of?

    Viruses consist of one or several pieces of nucleic acid (DNA or RNA) surrounded by a protein coat called a capsid.

  • What shapes can viral capsids have?

    Capsids can be helical, polyhedral, or complex in shape.

  • What is the function of a viral envelope?

    Some viruses have a membranous envelope with viral protein spikes that help infect host cells.

  • How do viruses affect host cells?

    Viruses turn host cells into virus factories and can insert into host DNA, sometimes causing cancer.

  • What is the central molecular chain of command in cells?

    The chain is DNA → RNA → Protein → Trait (Phenotype).

  • What is mitosis?

    Mitosis is the process by which most eukaryotes produce genetically identical daughter cells.

  • What is meiosis?

    Meiosis is the process of gamete formation (sperm and egg) involving reduction of chromosome number.

  • What is the germ theory of disease?

    The germ theory states that microbes cause disease, and these microbes are called pathogens.

  • What are Koch's Postulates?

    A 4-step process to prove a microbe causes disease: presence in diseased hosts, growth outside host, disease reproduction in healthy hosts, and re-isolation of the microbe.

  • What is aseptic technique?

    Aseptic technique is the method to isolate and grow microbes without contamination.

  • Who introduced handwashing and aseptic techniques to prevent disease?

    Semmelweis introduced handwashing; Lister introduced aseptic surgery; Florence Nightingale applied aseptic techniques to nursing.

  • What is epidemiology?

    Epidemiology is the study of disease distribution and determinants, exemplified by Snow's cholera mapping.