microbio

• Major groups of microorganisms and infectious agents

  • Bacteria (prokaryotes)
  • Archaea (prokaryotes)
  • Eukaryotic microorganisms (fungi, protists, algae)
  • Viruses
  • Prions
• Prokaryotic cells


  Lack a true nucleus, DNA is not enclosed in a membrane (nucleoid)
• Eukaryotic cells


  Have a true nucleus, DNA is enclosed in a membrane
• Bacteria are ubiquitous, found everywhere on the planet, even outnumbering the cells in the human body
• Ubiquitous


  A fancy term for everywhere
• Bacteria are ubiquitous, they can be found everywhere on the planet
• Bacteria and fungi play an important role in decomposing and recycling organic matter
• Microorganisms are used in many ways to benefit humanity, such as in food production, biotechnology, and bioremediation
• Pathogen


  Any agent or organism that causes disease
• Types of pathogens

  • Viruses
  • Bacteria
  • Fungi
  • Protozoa
  • Helminths
• Top causes of death by disease in the US


  • COVID-19
  • Influenza/Pneumonia
• Communicable disease


  A disease that can spread from person to person or animal to person
• Non-communicable disease


  A disease that is not caused by the spread of a germ, such as heart attack or stroke
• Weakened immune systems make people more susceptible to infections
• The three domains of life


  • Archaea
  • Eukarya
  • Bacteria
• Bacteria and archaea have non-membrane bound organelles like ribosomes
• Microorganisms are classified into 6 types: worms/helminths, fungi, protozoa, bacteria, viruses, and prions
• Viruses and prions are not considered living organisms, but rather acellular infectious agents
• Louis Pasteur disproved the concept of spontaneous generation through his famous swan-neck flask experiment
• Key discoveries of Louis Pasteur


  • Disproving spontaneous generation
  • Contributing to principles of vaccination
  • Demystifying fermentation
  • Proposing the germ theory of disease
• Early medical microbiologists discovered that microbes are ubiquitous and contribute to disease
• John Tyndall was the first to discover what are now known as bacterial endospores
• Early experiments showed that microbes are everywhere, they are ubiquitous - even the air has dust which is full of microbes and bacteria piggyback on that dust
• Before understanding the role of germs and disease, doctors wouldn't wash their hands or sterilize/disinfect their surgical equipment
• Bacterial endospores


  Heat resistant microbial structures that bacteria make, which standard boiling cannot kill
• John Tindale was the first to discover bacterial endospores
• Sterile means completely free from all forms of life including endospores and viral particles
• Robert Koch was the first to link a specific microorganism with a specific disease by developing his four postulates
• Koch used his four postulates to link the bacteria Bacillus anthracis to the disease Anthrax
• Nomenclature


  The assignment of scientific names to various taxonomic categories and individual organisms
• Taxonomy


  The field of biology that classifies and categorizes organisms based on their relatedness
• Taxonomic hierarchy

  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Binomial nomenclature


  A two-word scientific name, with the first word being the genus and the second the species
• Rules for binomial nomenclature: names are italicized, genus is capitalized, species is lowercase
• The phylogenetic tree shows the evolutionary relationships between different organisms, suggesting Archaea are more closely related to Eukarya than to Bacteria
• Prokaryotes are the simplest of all organisms and they include all bacteria
• Prokaryotes


  • Do not contain any membrane-bound organelles
  • Their genetic material is organized into single circular molecule of DNA that's concentrated in the area of the cell called the nucleoid region
• Domains of life

  • Archaea
  • Bacteria
  • Eukarya
• Bacteria


  • Prokaryotic cells that are found in almost every environment on Earth
  • Come in various shapes and sizes
  • Have a wide range of metabolic capabilities
  • Some are photosynthetic, others obtain energy by oxidizing inorganic compounds or by breaking down organic matter
  • Important in the cycling of nutrients throughout ecosystems
  • Some species are used in biotechnology
• Archaea


  • Also prokaryotic cells, but differ from bacteria in several ways
  • Have unique membrane lipids, cell wall components and ribosomal RNA sequences
  • Often live in very extreme conditions like hot springs or deep sea vents or Salt Flats
  • Important in biogeochemical cycles
  • Some species have industrial applications