Chapter 1.MicroPara

• Microbiology


  The study of organisms and agents usually too small to be seen by the unaided eye, or the study of objects <1mm diameter
• Microbiology is important because microorganisms serve in/as: decomposing dead organisms, decomposing industrial wastes, food for tiny animals, aid in digestion, production of fermented foods, and produce products used in manufacturing and treatment
• Knowledge in microbiology allows humans to prevent food spoilage, prevent disease occurrence, and led to aseptic techniques to prevent contamination in laboratories
• Domains of microbes


  • Eukarya (eukaryotic)
  • Bacteria (prokaryotic)
  • Archea (prokaryotic)
• Eukarya (eukaryotic)


  • Animals
  • Fungi
  • Protozoans
  • Helminth
• Bacteria (prokaryotic)


  • Bacteria
• Archea (prokaryotic)


  • Organisms that can live in extreme environments
• Microorganisms that are not medically-important
• After studying microbiology, students shall be able to: define microbiology and give its importance; differentiate the various types of microscopes and their uses; compare the various staining methods used to visualize microorganisms; classify the different types of culture media based on their physical state, chemical composition, and functional type; differentiate prokaryotes from eukaryotes; and characterize the different medically important microorganisms
• The cell wall is composed of peptidoglycan, which provides structural support to the bacterial cell.
• Peptidoglycan consists of alternating sugars (N-acetylglucosamine and N-acetylmuramic acid) crosslinked by short polypeptide chains.
• Gram staining distinguishes between gram-positive bacteria with thicker walls containing more peptidoglycan and gram-negative bacteria with thinner walls containing less peptidoglycan.
• Peptidoglycan consists of alternating sugars and amino acids crosslinked by short polypeptide chains.
• Gram-positive bacteria have thicker cell walls compared to gram-negative bacteria.
• Mycobacterium tuberculosis has an unusual cell wall structure with high lipid content.
• Gram stain is used to distinguish between Gram-positive bacteria with thick peptidoglycan layers and Gram-negative bacteria with thin peptidoglycan layers.
• Capsule: A layer of carbohydrates surrounding some bacteria, providing protection against phagocytosis.
• Bacteria have plasmids as extrachromosomal DNA elements that carry genes for antibiotic resistance or virulence factors.
• Bacteria have a rigid cell wall made up of peptidoglycan, which gives them shape and protects against osmotic lysis.
• Flagella: Hairlike structures that allow bacteria to move through liquids or along surfaces.
• Prokaryotes lack membrane-bound organelles such as mitochondria, chloroplasts, endoplasmic reticulum, Golgi apparatus, lysosomes, nucleus, cytoskeleton, ribosomes, centrioles, flagella, and vacuole.
• Bacteria are classified into two main groups based on the presence or absence of a cell wall: Gram-positive and Gram-negative.
• Mycobacterium tuberculosis has an unusual cell wall structure called mycolic acid, making it resistant to certain antibiotics like rifampin.
• Some bacteria can produce capsules or slime layers outside their cell walls, providing additional protection against phagocytosis.
• Eukaryotes possess all these structures except for flagella and vacuole.
• Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall, while gram-negative bacteria have a thin layer of peptidoglycan surrounded by an outer membrane.
• The cytoplasmic membrane separates the bacterial cell from its environment and regulates transport of molecules into and out of the cell.
• Streptococcus pyogenes is a type of streptococcus that causes scarlet fever and other diseases.
• Mycobacterium tuberculosis has a waxy cell wall that makes it difficult to stain using traditional techniques.
• Bacteria can be classified based on their shape as cocci (spherical), bacilli (rod-shaped), spirilla (spiral-shaped), or vibrio (curved rod).
• The outer membrane of Gram-negative bacteria contains lipopolysaccharides, which are endotoxins that can cause fever when released into the bloodstream.
• Flagella: Hairlike structures that allow bacteria to move through fluids or on surfaces.
• Fimbriae (pili): Short hairlike appendages involved in adherence to host cells.
• Cocci are spherical cells that may occur singly, in pairs (diplococcus), clusters (streptococcus), tetrads (tetracoccus), or irregular groups (staphylococcus).
• Lipoteichoic acid is found on the surface of some bacterial cells and acts as a receptor for phagocytosis.
• Some bacteria can exchange genetic material through conjugation, where two cells come into contact and transfer DNA.
• Some bacteria can exchange genetic material through conjugation, where two cells come into contact and transfer DNA.
• Fimbriae/pili: Short hairlike appendages involved in adhesion to host cells and transfer of genetic material during conjugation.
• Bacteria may also produce capsules or slime layers that protect them from host defenses and allow them to adhere to surfaces.
• Some bacteria can exchange genetic material through conjugation, where two cells come into contact and transfer DNA.