Unit-1 notes_fundamentals of micro.docx

**Unit: 1** **1. Antony van Leeuwenhoek (1632--1723)** - **1674**: **Discovery of Microorganisms** -- Van Leeuwenhoek is credited with being the first person to observe and describe microorganisms, which he called \"animalcules.\" He used a single-lens microscope he designed himself....

**Unit: 1** **1. Antony van Leeuwenhoek (1632--1723)** - **1674**: **Discovery of Microorganisms** -- Van Leeuwenhoek is credited with being the first person to observe and describe microorganisms, which he called \"animalcules.\" He used a single-lens microscope he designed himself. - **1676**: **Observation of Bacteria** -- He reported the first observation of bacteria, noting their movement and diverse shapes. - **1683**: **Description of Oral Bacteria** -- He provided detailed descriptions of bacteria found in dental plaque, identifying different shapes like rods and spirals. - **1687**: **Observation of Red Blood Cells** -- Van Leeuwenhoek observed and described red blood cells, spermatozoa, and muscle fibers. - **1693**: **Discovery of Protozoa** -- He observed and described protozoa, which he referred to as \"animalcules.\" **2. Louis Pasteur (1822--1895)** - **1857**: **Discovery of Fermentation** -- Pasteur demonstrated that microorganisms are responsible for fermentation, disproving the theory of spontaneous generation. - **1861**: **Germ Theory of Disease** -- Pasteur proposed that many diseases are caused by microorganisms, laying the groundwork for the germ theory of disease. - **1862**: **Pasteurization** -- He developed the process of pasteurization, a technique to prevent the spoilage of wine and milk by heating them to a temperature that kills harmful bacteria. - **1879**: **Development of Vaccines** -- Pasteur developed the first vaccine for chicken cholera and later for anthrax (1881) and rabies (1885), pioneering the field of immunology. **3. Robert Koch (1843--1910)** - **1876**: **Discovery of Anthrax Bacillus** -- Koch identified Bacillus anthracis as the causative agent of anthrax, proving the germ theory of disease. - **1882**: **Discovery of Mycobacterium tuberculosis** -- Koch discovered the bacterium responsible for tuberculosis, a major milestone in medical microbiology. - **1883**: **Discovery of Vibrio cholerae** -- Koch identified the bacterium that causes cholera during his work in Egypt and India. - **1884**: **Koch\'s Postulates** -- He formulated a set of criteria, known as Koch\'s postulates, for establishing a causal relationship between a microorganism and a disease. **Koch\'s Postulates:** 1. **The microorganism must be found in abundance in all organisms suffering from the disease but should not be found in healthy organisms.** - **Explanation**: The pathogen should be present in every case of the disease and absent in healthy individuals. This ensures that the microorganism is associated with the disease. 2. **The microorganism must be isolated from a diseased organism and grown in pure culture.** - **Explanation**: The pathogen must be isolated from the diseased host and grown in a laboratory setting in a pure culture, meaning no other microorganisms are present. 3. **The cultured microorganism should cause disease when introduced into a healthy, susceptible organism.** - **Explanation**: The isolated and cultured microorganism should be able to cause the same disease when introduced into a healthy host, proving its pathogenicity. 4. **The microorganism must be re-isolated from the experimentally infected host and identified as being identical to the original specific causative agent.** - **Explanation**: After the microorganism causes disease in the healthy host, it must be re-isolated and shown to be the same as the original microorganism isolated from the first diseased host. This confirms the specific microorganism\'s role in causing the disease. **4. Joseph Lister (1827--1912)** - **1865**: **Antiseptic Surgery** -- Lister introduced the use of carbolic acid (phenol) as an antiseptic to sterilize surgical instruments and clean wounds, drastically reducing post-surgical infections. - **1867**: **Publication on Antiseptic Principles** -- Lister published his findings on antiseptic surgery in \"The Lancet,\" promoting the importance of sterilization in medical procedures. - **1870**: **Introduction of Sterilized Catgut** -- Lister introduced the use of sterilized catgut for internal sutures, further improving surgical outcomes. - **1871**: **Antiseptic Treatment of Compound Fractures** -- Lister applied antiseptic methods to treat compound fractures, demonstrating a significant reduction in infection rates. **5. Edward Jenner (1749--1823)** - **1796**: **Development of Smallpox Vaccine** -- Jenner performed the first successful vaccination by using material from cowpox lesions to create immunity to smallpox, a groundbreaking discovery in immunology. - **1798**: **Publication of Vaccination Findings** -- Jenner published his work on vaccination, titled \"An Inquiry into the Causes and Effects of the Variolae Vaccinae,\" leading to widespread adoption of the smallpox vaccine. - **1801**: **Advocacy for Vaccination** -- Jenner advocated for the global use of vaccination to eradicate smallpox, setting the foundation for modern immunization programs. **6. Alexander Fleming (1881--1955)** - **1928**: **Discovery of Penicillin** -- Fleming discovered penicillin, the first true antibiotic, by observing that the mold Penicillium notatum inhibited the growth of Staphylococcus bacteria. - **1929**: **Publication on Penicillin** -- Fleming published his findings on penicillin\'s antibacterial properties, though it would take years before it was developed into a widely used antibiotic. - **1940s**: **Mass Production of Penicillin** -- During World War II, the mass production of penicillin was achieved, revolutionizing the treatment of bacterial infections and saving countless lives. **Introduction to Bacteria, Viruses, Fungi, and Protozoan's** **1. Bacteria** **Definition**: Bacteria are unicellular, prokaryotic microorganisms that lack a true nucleus and membrane-bound organelles. They are found in virtually every environment on Earth, from soil and water to extreme environments like hot springs and deep-sea vents. **Morphological Characteristics**: - **Shape**: Bacteria exhibit various shapes, which are key to their identification: - **Cocci**: Spherical or oval-shaped. They can occur singly (Micrococcus), in pairs (Diplococcus), in chains (Streptococcus), or in clusters (Staphylococcus). - **Bacilli**: Rod-shaped bacteria that can be single (Escherichia coli) or in chains (Bacillus). - **Spirilla**: Spiral-shaped bacteria, which can be rigid (Spirillum) or flexible (Spirochaetes like Treponema). - **Vibrio**: Comma-shaped, resembling a curved rod (Vibrio cholerae). - **Size**: Bacteria are typically 0.2 to 2.0 micrometers in diameter. - **Cell Wall**: Composed mainly of peptidoglycan, which provides structural support. Bacteria can be classified as: - **Gram-positive**: Thick peptidoglycan layer, stains purple (Staphylococcus aureus). - **Gram-negative**: Thin peptidoglycan layer and an outer membrane, stains pink (Escherichia coli). - **Motility**: Some bacteria are motile and possess flagella (e.g., Salmonella), while others are non-motile. **Classification**: - **Domain**: Bacteria - **Kingdom**: Monera (or Bacteria) - **Examples**: - *Escherichia coli* (E. coli) -- Gram-negative rod. - *Staphylococcus aureus* -- Gram-positive cocci. - *Mycobacterium tuberculosis* -- Acid-fast bacterium causing tuberculosis. **Reproduction**: - **Asexual**: - **Binary Fission**: The primary mode of bacterial reproduction where a single bacterial cell divides into two identical daughter cells. - **Horizontal Gene Transfer**: - **Conjugation**: Transfer of genetic material between bacterial cells through direct contact. - **Transformation**: Uptake of free DNA from the environment by a bacterial cell. - **Transduction**: Transfer of DNA from one bacterium to another via bacteriophages (viruses that infect bacteria). **2. Viruses** **Definition**: Viruses are non-cellular, obligate intracellular parasites that consist of genetic material (DNA or RNA) enclosed in a protein coat called a capsid. They can only replicate inside a host cell. **Morphological Characteristics**: - **Size**: Viruses are much smaller than bacteria, typically 20 to 300 nanometers. - **Shape**: - **Icosahedral**: Symmetrical, spherical appearance (Adenovirus). - **Helical**: Rod-like structure (Tobacco mosaic virus). - **Complex**: Combination of icosahedral and helical structures (Bacteriophage). - **Components**: - **Capsid**: Protein coat made up of capsomeres. - **Envelope**: Some viruses have an outer lipid membrane derived from the host cell membrane (Influenza virus). - **Genetic Material**: Either DNA or RNA, which can be single-stranded or double-stranded, linear or circular. **Classification**: - **By Genetic Material**: - **DNA Viruses**: Adenovirus, Herpesvirus. - **RNA Viruses**: Influenza virus, HIV. - **By Host Range**: - **Bacteriophages**: Viruses that infect bacteria (T4 bacteriophage). - **Animal Viruses**: Infect animal cells (Rabies virus). - **Plant Viruses**: Infect plant cells (Tobacco mosaic virus). **Reproduction**: - **Lytic Cycle**: - **Attachment**: Virus binds to the host cell surface. - **Penetration**: Viral genetic material enters the host cell. - **Biosynthesis**: Viral components are synthesized by the host cell\'s machinery. - **Assembly**: New viral particles are assembled. - **Release**: Host cell bursts, releasing new viruses (e.g., T4 bacteriophage). - **Lysogenic Cycle**: - The viral DNA integrates into the host genome and replicates along with it without causing immediate destruction of the host cell (e.g., Lambda phage). - **3. Fungi** **Definition**: Fungi are eukaryotic organisms that can be unicellular (yeasts) or multicellular (molds, mushrooms). They are non-photosynthetic and obtain nutrients by absorption. **Morphological Characteristics**: - **Structure**: - **Yeasts**: Unicellular fungi, typically oval or spherical (Saccharomyces cerevisiae). - **Molds**: Multicellular fungi with filamentous structures called hyphae, which form a network known as mycelium (Aspergillus). - **Mushrooms**: Fruiting bodies of certain fungi, with a cap and stalk (Agaricus). - **Cell Wall**: Composed of chitin and glucans. - **Spores**: Reproductive units of fungi, can be asexual or sexual. - **Dimorphism**: Some fungi can switch between yeast and mold forms depending on environmental conditions (Histoplasma capsulatum). **Classification**: - **Kingdom**: Fungi - **Phyla**: - **Ascomycota**: Sac fungi (Penicillium). - **Basidiomycota**: Club fungi (Agaricus). - **Zygomycota**: Conjugation fungi (Rhizopus). - **Chytridiomycota**: Aquatic fungi (Batrachochytrium). **Reproduction**: - **Asexual**: - **Budding**: Seen in yeasts like *Saccharomyces cerevisiae*. - **Fragmentation**: Hyphae break into pieces, each capable of growing into a new fungus. - **Spore Formation**: Conidia or sporangiospores formed by mitosis (Aspergillus). - **Sexual**: - **Plasmogamy**: Fusion of two hyphae of opposite mating types. - **Karyogamy**: Fusion of nuclei. - **Meiosis**: Produces sexual spores like ascospores, basidiospores. **4. Protozoans** **Definition**: Protozoans are unicellular, eukaryotic microorganisms that can be free-living or parasitic. They are heterotrophic and exhibit a variety of morphologies. **Morphological Characteristics**: - **Shape**: Protozoans have diverse shapes and structures: - **Amoeboid**: Irregular shape with pseudopodia for movement and feeding (Amoeba). - **Ciliated**: Covered with cilia for movement (Paramecium). - **Flagellated**: Possess one or more flagella (Trypanosoma). - **Sporozoans**: Non-motile, with complex life cycles (Plasmodium). - **Size**: Typically range from 10 to 52 micrometers, but can be larger. - **Cell Structure**: - **Nucleus**: Usually a single nucleus, but some have multiple nuclei. - **Organelles**: Include mitochondria, food vacuoles, contractile vacuoles, etc. **Classification**: - **Kingdom**: Protista - **Phyla**: - **Sarcodina**: Amoeboid protozoans (Amoeba). - **Ciliophora**: Ciliated protozoans (Paramecium). - **Mastigophora**: Flagellated protozoans (Giardia). - **Sporozoa**: Parasitic protozoans (Plasmodium). **Reproduction**: - **Asexual**: - **Binary Fission**: Division of a single protozoan into two identical daughter cells (Amoeba). - **Multiple Fission**: Nucleus divides multiple times before the cell splits into many daughter cells (Plasmodium). - **Sexual**: - **Conjugation**: Exchange of genetic material between two protozoans (Paramecium). - **Syngamy**: Fusion of gametes to form a zygote.