Microbiology Lecture 1 PDF

# Microbiology lecture 1 ## Dr.Ikhlas Attia _Translated by: Muslim Aqeel_ ## Introduction of Microbiology: ### I. OVERVIEW - Microbiology is the branch of biology that studies microorganisms, including bacteria, viruses, fungi, protozoa, and algae. - These microscopic organisms are essential to...

# Microbiology lecture 1 ## Dr.Ikhlas Attia _Translated by: Muslim Aqeel_ ## Introduction of Microbiology: ### I. OVERVIEW - Microbiology is the branch of biology that studies microorganisms, including bacteria, viruses, fungi, protozoa, and algae. - These microscopic organisms are essential to life on Earth due to their role in processes such as decomposition, nutrient recycling, and in maintaining human health. - While some microbes are pathogenic, many are beneficial, especially in fields like medicine, biotechnology, and pharmacy. - Microorganisms exist in every ecosystem. - They form close associations with all multicellular organisms, including humans. - Our bodies host billions of these microbes as part of the normal flora - most of which are harmless or even helpful (some bacteria aid in digesting food in the intestines). - Some microorganisms, however, are harmful and are known as pathogens. - Infectious diseases typically begin when microorganisms colonize the body. - This means they settle and grow on the skin or mucous membranes. - Some infections, however, occur when microbes are introduced directly into the bloodstream or internal organs. - Once a microorganism colonizes the body, one of two things may happen: - The immune system eliminates it without harm to the host. - The microorganism multiplies, leading to an infection. - When infection results in tissue damage and disrupts normal bodily functions, it is considered an infectious disease. ### Discovery of Microorganisms and Microscopy Era > The discovery of microorganisms was made possible by the invention of the microscope, which allowed scientists to observe microscopic life for the first time. **Two key figures of this era were:** - **Anton van Leeuwenhoek (1632-1723):** A Dutch merchant known as the "Father of Microbiology," he built microscopes that magnified up to 200-300 times. In 1674, he was the first to observe bacteria, yeast, and blood cells, calling them "animalcules." His findings were initially met with skepticism but eventually convinced the scientific community of the existence of microscopic life. - **Robert Hooke (1635-1703):** An English scientist who coined the term "cell" in his book *Micrographia* (1665) after observing cork under a microscope. He also studied fungi and other microorganisms, expanding knowledge in this field. - Improvements in microscopy in the 17th century, especially Leeuwenhoek's simple microscope, allowed for greater magnification. - This level was not surpassed until the 19th century. - Leeuwenhoek and Hooke's work laid the groundwork for the germ theory and helped disprove the theory of spontaneous generation. ## Transition to Modern Microbiology: - By the late 19th century, advances in staining techniques, sterilization, and improved microscopy gave rise to modern microbiology. - These advancements helped scientists like Louis Pasteur and Robert Koch disprove spontaneous generation and understand microorganisms' role in causing diseases. - **Louis Pasteur (1822-1895):** A French scientist known for disproving spontaneous generation, developing the principles of vaccination, and creating pasteurization. His work formed the basis of germ theory. - **Robert Koch (1843-1910):** A German physician who developed Koch's Postulates to link specific microbes to diseases. He discovered the bacteria responsible for tuberculosis, cholera, and anthrax. ## Golden Age of Microbiology (Mid-19th to Early 20th Century) - This period saw major discoveries in disease prevention and treatment. - **Edward Jenner (1749-1823):** Developed the smallpox vaccine, introducing the concept of vaccination. - **Joseph Lister (1827-1912):** Introduced antiseptic surgery, using carbolic acid to prevent infections, which greatly improved surgical outcomes. - **Alexander Fleming (1881-1955):** Discovered penicillin in 1928, the first widely used antibiotic, revolutionizing the treatment of bacterial infections. ## II. PROKARYOTIC PATHOGENS - All prokaryotic organisms are classified as bacteria, whereas eukaryotic organisms include fungi, protozoa, and helminths, as well as humans. - Prokaryotic organisms are divided into two major groups: - **The eubacteria**, which include all bacteria of medical importance. - **The archaebacteria**, a collection of evolutionarily distinct organisms. - Cells of prokaryotic and eukaryotic organisms differ in several significant structural features as illustrated below: | Feature | Prokaryotes | Eukaryotes | |---|---|---| | Size | Small (0.1-5 micrometer) | Large (10-100 micrometer) | | DNA | Nucleoid, circular DNA without nuclear membrane | True nucleus with nuclear membrane, Linear DNA | | Number of cells | Unicellular | Unicellular and Multicellular | | Chromosomes | Haploid (have one set of chromosomes) | Diploid (have two sets of chromosomes) | | Cell wall | Present | Present | | Ribosomes | Small ribosomes | Large ribosomes | | Vacuoles | Present | Present | | Cell division | Binary fission | Meiosis | | Organelles | Absent: Plastids, mitochondria, endoplasmic reticulum, Golgi apparatus | Present: Plastids, mitochondria, endoplasmic reticulum, Golgi apparatus | | Examples | Bacteria, archaea, and blue-green algae (cyanobacteria) | Fungi, algae, protozoa, and animals | ### A. Typical bacteria: - Most bacteria have shapes that can be described as either a rod, sphere, or corkscrew. - Prokaryotic cells are smaller than eukaryotic cells. - Nearly all bacteria, with the exception of mycoplasma, have a rigid cell wall surrounding the cell membrane that determines the shape of the organism. - The cell wall also determines whether the bacterium is classified as gram-positive or gram-negative. - External to the cell wall may be flagella, pili, and/or a capsule. - Bacterial cells divide by binary fission. - However, many bacteria exchange genetic information carried on plasmids - small, specialized genetic elements capable of self-replication - including the information necessary for establishment of antibiotic-resistance. ### B. Atypical bacteria: - Atypical bacteria include groups of organisms such as Mycoplasma, Chlamydia, and Rickettsia that although prokaryotic, lack significant characteristic structural components or metabolic capabilities that separate them from the larger group of typical bacteria. ## III. FUNGI - Fungi are non-photosynthetic, generally saprophytic, eukaryotic organisms. - Some fungi are filamentous, and are commonly called molds, whereas others - the yeasts are unicellular. - Fungal reproduction may be asexual, sexual, or both, and all fungi produce spores. - Pathogenic fungi can cause diseases, ranging from skin infections (superficial mycoses) to serious, systemic infections (deep mycoses). ## IV. PROTOZOA - Protozoa are single-celled, non-photosynthetic, eukaryotic organisms that come in various shapes and sizes. - Many protozoa are free-living, but others are among the most clinically important parasites of humans. - Members of this group infect all major tissues and organs of the body. - They can be intracellular parasites, or extracellular parasites in the blood, urogenital region, or intestine. - Transmission is generally by ingestion of an infective stage of the parasite or by insect bite. - Protozoa cause a variety of diseases. ## V. HELMINTHS - Helminths are groups of worms that live as parasites. - They are multicellular, eukaryotic organisms with complex body organization. - They are divided into three main groups: tapeworms (cestodes), flukes (trematodes), and roundworms (nematodes). - Helminths are parasitic, receiving nutrients by ingesting or absorbing digestive contents or ingesting or absorbing body fluids or tissues. - Almost any organ in the body can be parasitized. - All major groups of helminths can cause disease in humans. - **Protozoa** - Flagellates (Giardia intestinalis) - Amebae (Entamoeba) - Sporozoa (Plasmodium) - Ciliates (Balantidium coli) - **Helminths** - Nematodes (Ascaris lumbricoides) - Trematoda (Fasciola hepatica) - Cestoda (Taenia) ## VI. VIRUSES - Viruses are obligate intracellular parasites that do not have a cellular structure. - A virus consists of molecules of DNA (DNA virus) or RNA (RNA virus), but not both, surrounded by a protein coat. - A virus may also have an envelope derived from the plasma membrane of the host cell from which the virus is released. - Viruses contain the genetic information necessary for directing their own replication, but require the host's cellular structures and enzymatic machinery to complete the process of their own reproduction. - The fate of the host cell following viral infection ranges from rapid lysis releasing many progeny virions, to gradual, prolonged release of viral particles. - Viruses cause a broad spectrum of diseases. > **(A)** > - Envelope protein > - DNA > - Envelope > - Capsid > - Matrix > **(B)** > - Envelope protein > - RNA > - Envelope > - Capsid > - Matrix > Any errors in the translation, please contact me on Telegram @mq1hf. Note: Please ignore minor errors. Thank you.