Microbiology - The Science

• The cell wall is composed of peptidoglycan, which provides structural support to the bacterial cell.
• microbiology


  The study of microbes
• What are microbes?

  Organisms too small to be viewed by the naked eye.
• Why study microbiology?

  a. Medical field careers- treating your patients, preventing spread of disease

  b. Your own health - doctors & nurses don't know everything

  c. Commercial reasons- many drugs & alcohols

  d. Travel- vaccines for certain areas of the world

  e. Food industry

  1. Contamination prevention (food recalls, food poisoning, etc)

  2. Production of alcohol, cheese, bread, yogurt, pickles, etc
• Nomenclature

  Genus & Species
• Staphylo


  cluster arrangement
• Bacteria

  cell walls contain peptidoglycan
• Types of microbes

  1. Bacteria 2. Archaea 3. Eukarya
• Archaea

  (if present cell walls lack peptidoglycan) Extremes!! Halophiles (salt mines), thermophiles ("old reliable" gyser), etc
• Eukarya


  o Protists (slime molds, protozoa, algae)

  o Fungi (unicellular yeasts, multi-cellular molds, mushrooms)

  o Plants (mosses, ferns, conifers, flowering plants)

  o Animals (sponges, worms, insects, vertebrates)
• Viruses are not

  cells
• Viruses

  They are a kind of informational parasite ("bad news enveloped in protein"). Viruses are classified separately. They consist of DNA or RNA surrounded by a protein coat. Some possess an envelope coating.
• Helminths


  multi-cellular animal parasites (roundworms, flatworms, etc)
• Many microbes live as

  single cells or cell clusters. Some are multi-cellular (e.g. filamentous multicells), but not as complex as animals or plants.
• Not all microbes are considered

  pathogenic (disease causing).
• 1. Only members of the Kingdom Animalia (and most Plantae) are not considered


  microbes
• Normal Microbiota (flora)


  present on all humans always does no harm to human carriers.
• Pathogens


  invade the host and result in disease
• Benefits of Microbes in Our World:

  • Bioremediation • Insect Pest Control • Recycling Vital Elements • Biotechnology & genetic engineering
• used microscope to discover life's smallest structural units were little boxes or "cells". Beginning of Cell Theory- all living things composed of cells.


  • 1665: Robert Hooke
• tried to disprove Spontaneous Generation. He used sealed jars to prove that maggots don't arise spontaneously from decaying meat. Maggots only appeared in open jars after flies laid eggs.


  • 1668: Francesco Redi
• was first to observe live microbes/animalcules.

  • 1673-1723: Antoni van Leeuwenhoek (a merchant)
• developed the vaccination process

  • 1796: Edward Jenner
• proved microbes are in non living matter (air, water, etc) & can contaminate sterile solutions but non living matter itself does not create microbes. Also, proved microbes can be killed by heat.


  Louis Pasteur
• solved the spoilage of wine & beer through process of pasteurization- killing most of the problematic bacteria through heat. Now used in milk.

  Louis Pasteur
• developed "Germ Theory of Disease". Koch discovered rod shaped bacteria in cattle killed by anthrax.


  • 1876: Robert Koch
• tested hundreds of substances to find a chemotherapeutic agent (salvarsan- arsenic derivative against syphilis).


  • 1910: Paul Ehrlich
• discovered antibiotics by accident.

  • 1928: Alexander Fleming
• Our World in Constant Fluctuation:

  • Disease disappears - polio

  • Disease reappears - mumps (people refusing vaccination), pertussis-whooping cough (vaccine does not protect for a lifetime)

  • Disease emerges - bovine spongiform encephalitis (BSE or mad cow), invasive group A streptococcus (flesh eating bacteria), ebola hemorrhagic fever, AIDS, HIV, SARS, Swine Flu.
• Causes of Emerging Infectious Diseases:

  1. Evolutionary changes in existing organisms

  2. Spread of known diseases to new areas or populations

  3. Increasing human exposure to infectious agents in areas undergoing ecological change (ex: deforestation)
• Microbiology


  The study of microbes
• Types of microbes


  • Acellular (viruses, virions, prions)
  • Cellular (bacteria, algae, archaea, protozoa, fungi)
• Subdivisions of cellular microorganisms

  • Eukaryotic (algae, protozoa, fungi)
  • Prokaryotic (bacteria, archaea)
• Virus replication


  Viruses must invade live host cells to replicate
• Some viruses, called oncogenic viruses or oncovirus, cause specific types of cancer
• Viruses have five specific properties that distinguish them from living cells
• Characteristics used to classify viruses

  • Type of genetic material, whether the virus nucleic acid is single or double stranded, whether it is positive-sense or negative-sense, shape of the capsid, number of capsomers, size of the capsid, presence or absence of an envelope, type of host it infects, type of disease it produces, target cell, immunologic or antigenic properties
• Three major theories explain the origin of viruses: coevolution theory, retrograde evolution theory, escaped gene theory
• Viruses that infect humans and animals are collectively referred to as animal viruses
• Steps in the Multiplication of Animal Viruses


  Attachment (absorption), Penetration, Uncoating, Biosynthesis, Assembly, Release