Flashcards in Lecutre 1 Deck (14):
Standard (traditional) Definition of Microbiology
Study of organisms too small to be seen by the naked or unaided eye. Includes
the roles of microorganisms in causing disease, changes they make in the environment
and products that they generate.
2 major problems with the definition
Organisms refer only to living cells
The naked or unaided eye can visualize objects as small as 0.1mm
to the study of microorganisms, we also study infectious agents such as viruses, prions and viroids that are not considered to be living. We refer to theses non-living
agents as particles
Animals, Plants, Protozoans, Fungi – all made of the Eukaryotic cells and the Prokaryotes (Monera)
The field of study includes
1. Protozoa (Eukaryotic cells)-usually unicellular
2. Algae (Eukaryotic cells)-some are macroscopic
3. Fungi (Eukaryotic cells)-some are macroscopic-includes yeasts and molds
4. Bacteria (Prokaryotic cells) and cyanobacteria (also known as the bluegreen
algae Prokaryotic cells)
(a type of bacteria and therefore Prokaryotic cells) These
organisms have leaky membranes and must exist inside of host cells. An example of a rickettsial organism is Rickettsia rickettsii. This is the etiological agent (cause of disease) of Rocky Mountain Spotted Fever
what is a venereal disease?
(a type of bacteria and therefore Prokaryotic cells) these
organisms lack enzymes and therefore some of the metabolic machinery they need. An example of a chlamydial organism is Chlamydia trachomatis. This is the etiological agent of NGU or nongonococcal urethritis, a common venereal disease. A venereal disease is a disease that is directly transmitted from one mucous membrane to another
when can they replicate?
kind of parasite?
(not cells, not living, a type of particle-simplest version consists of nucleic acid surrounded by a protein coat) Viruses can only replicate wheninside a host cell. They are obligate intracellular parasites like Rickettsia
Naming system for Viruses
Since they are not living and therefore not organisms, we do not use Binomial Nomenclature to name them. System for naming is not very well organized.
Since HIV attacks the immune system (defense system) those with AIDS suffer secondary or opportunistic infections. One such infection would be Pneumocystic pneumonia. This is caused (etiological agent) by a protozoan called Pneumocystis carinii (also Pneumocystis jirovecii) Some believe this organism is a fungus – we will refer to it as a protozoan.
what are they responsible for causing
(not cells, not living, no nucleic acid, a type of particle) – infectious naked pieces of protein. They are obligate intracellular parasites. Prions are responsible for causing BSE or Bovine Spongiform Encephalopathy also called Mad Cow disease.
(not cells, not living, a type of particle) – naked pieces of RNA. Associated mostly with plant pathology (disease).
Etiological Agent of AIDS
and info behind naming it
An example of a virus is HIV (Human Immunodeficiency Virus). This is the etiological agent of AIDS (Acquired Immune Deficiency Syndrome). Historically named HTLV III (Human T-cell lymphotropic virus III by American researchers) and LAV
(Lymphadenopathy associated virus by French researchers).