History And Scope Of Microbiology 4f286e

HISTORY AND SCOPE OF MICROBIOLOGY (2) What is Microbiology? (a) Microbiology is "the study of microbes, organisms so small that a microscope is needed to study them." (b) Microbiology, as a science, may be differentiated along organism lines ("the variety of kinds of microbes") and in of techniques and goals ("the kind of work microbiologists do") (4) Bacteria (chapters 4, 6, 7, 8, 9) (a) The bacteria have the following characteristics: (i) Relatively small (ii) Single-celled (iii) No nucleus or other membrane-bound organelles (iv) Simple morphologies (v) Primarily synthesizers or absorbers (i.e., not engulfers) (b) Most bacteria do not cause human diseases, but most infectious diseases are caused by bacteria (and viruses) (c) More typically, bacteria are beneficial, whether to ecosystems or directly to individual organisms (d) [bacteria (Google Search)] [index] (5) Algae (chapters 4, 11) (a) The algae have the following characteristics: (i) Both unicellular and multicellular types (ii) Generally aquatic (iii) Contain nucleus and other membrane-bound organelles (iv) Photosynthetic (b) Algae typically are beneficial (to ecosystems) though some can cause damage (c) Only a few contribute to human disease (d) [algae (Google Search)] [eukaryotic microorganisms and parasites, algae (supplementary lecture) (MicroDude)] [index] (6) Fungi (chapters 4, 11) (a) The fungi generally have the following characteristics: (i) Both unicellular and multicellular types (ii) Generally not aquatic (i.e., prefer dryer environments) (iii) Contain nuclei and other membrane-bound organelles (iv) Nutrient absorbers (not photosynthetic and not engulfers) (v) Decomposers (b) Single-celled fungi are called yeasts (c) Multicelled fungi are called molds (d) There are a number of fungi-caused human diseases (e.g., athletes foot, Candida yeast infections) (e) In the environment fungi serve as plant symbionts and decomposers (f) [fungi or fungus (Google Search)] [eukaryotic microorganisms and parasites, fungi (supplemental lecture) (MicroDude)] [index] (7) Viruses (chapters 8, 10) (a) (b) (c)

Viruses are not cells Instead they are acellular, obligate intracellular parasites (i.e., they must invade a cell to replicate) Generally viruses are much smaller than cellular organisms

(d)

Viruses either cause diseases or are sufficiently benign that they infect without causing damage to the host; in some cases viruses can be beneficial to their hosts (e.g., lysogenic conversion) (e) [virology and introduction (Google Search)] [viruses (MicroDude)] [index] (8) Protozoa (chapters 4, 11) (a) The protozoa generally have the following characteristics: (i) Unicellular (ii) Aquatic (or, minimally, grow and reproduce in moist environments) (iii) Contain nucleus and other membrane-bound organelles (iv) Mostly engulfers though some absorbers and, depending on the classification scheme, also photosynthesizers (b) The absorbers tend to be parasitic and cause disease (c) [protozoa, parasitology (Google Search)] [eukaryotic microorganisms and parasites, protozoa (supplemental lecture) (MicroDude)] [index] (9) Helminths (chapter 11) (a) These are parasitic worms (as well numerous non-parasitic types) (b) Parasitic worms are a province of microbiology because (i) They share with other microorganisms their capacity to cause infectious disease (ii) They are studied using techniques which overlap those employed to study other microorganisms (e.g., microscopes) (c) Helminths, however, are certainly not as small as the more-typical objects of microbiological study (i.e., bacteria, viruses, protozoa, etc.) (d) [helminths, parasitic worms (Google Search)] [eukaryotic microorganisms and parasites (MicroDude)] [multicellular parasites (supplemental lecture) (MicroDude)] [index] (10) Arthropods (a) Though not considered microorganisms, arthropods (e.g., insects) are important vectors of infectious-disease propagation (b) For example, mosquitoes transmit malaria, which is caused by a protozoa (c) [arthropod vector, arthropod vectors (Google Search)] [eukaryotic microorganisms and parasites (MicroDude)] [arthropod vectors (supplemental lecture) (MicroDude)] [index] (12) History of microbiology (a) We will briefly outline the history of microbiology in of the achievements of a few individuals (yes, this will be on the test) including (i) Robert Hooke (ii) Anton van Leeuwenhoek (iii) Those individuals involved directly in defining the germ theory of disease (b) [microbiology and history (Google Search)] [significant events of the last 125 years (American Society for Microbiology)] [index] (13) Hooke, Robert (~1665) (a) Builder of the first (or, at least, an early) compound microscope (b) Coined the term �cell� (c) [Perhaps his most famous microscopical observation was his study of thin slices of cork. He wrote: '�I could exceedingly plainly perceive it to be all perforated and porous� these pores, or cells, �were indeed the first microscopical pores I ever saw, and perhaps, that were ever seen, for I had not met with any Writer or Person, that had made any mention of them before this.' Hooke had discovered plant cells -- more precisely, what Hooke saw were the cell walls in cork tissue" (Enter Evolution: Theory and History)] (d) [Robert Hooke (Google Search)] [Robert Hooke (1635-1703) (Enter Evolution: Theory and History)] [index] (14) van Leeuwenhoek, Anton (mid to late 1600s, early 1700s) (a) The first microbiologist (Leeuwenhoek is more-or-less pronounced layu-wen-hook) (b) First to use microscopes to view microorganisms (c) [van Leeuwenhoek (Google Search)] [Antony van Leeuwenhoek (1632-1723) (Enter Evolution: Theory and History)] [history of the microscope(Brian J. Ford)] [Leeuwenhoek

microscope (Molecular Expressions Museum of Microscopy)] [Leeuwenhoek's perception of the spermatozoa(niclely places Leeuwenhoek in his time) (Zygote)] [index] (15) Germ theory of disease (a) The germ theory of disease is the idea that diseases may be caused by microscopic organisms (i.e., not visible to the naked eye), a.k.a., microbes (b) The germ theory of disease was not quick to catch on because of the contrasting concept of spontaneous generation which is an idea that life can arise spontaneously from no longer living things; for example, (i) The "spontaneous" clouding of clear broth (ii) The occurrence of maggots on meat (c) The idea of spontaneous generation was debunked by experiments by (i) sco Redi (ii) Louis Pasteur (iii) Etc. (d) Others that contributed to the development and practical application of the germ theory of disease include (i) Robert Koch (ii) Ignaz Semmelweis (iii) Joseph Lister (iv) Edward Jenner (v) Alexander Fleming (vi) Etc. (e) [germ theory of disease (Google Search)] [index] (16) Redi, sco (a) Showed that meat protected from flies via a gauze barrier did not develop maggots, hence were not spontaneously generated (17) Pasteur, Louis (mid to late 1800s) (a) Building on the experiments of others, Pasteur showed that boiled broth did not become cloudy (turbid) when air but not dust could the broth (b) Built elegant "swan-necked" flasks which trapped dust (and microorganisms) along their curved necks, thus showing that neither air nor broth were sufficient to allow the generation of microorganisms (it is the microorganisms, e.g., bacteria, that scatter light thereby producing turbidity in broth cultures) (c) Pasteur additionally showed that cotton plugs (a primitive air-filtration device) could prevent

microbes from reaching otherwise air-exposed sterile broths (d) Note that Pasteur was fortunate that the foods he boiled into broths did not contain bacterial spores since such spores are resistant to killing by boiling (e) Pasteur invented pasteurization, the heating of foods to eliminate harmful microorganisms while retaining not-harmful microorganisms (f) He was responsible for the association of specific microbes with diseases (g) He development the rabies vaccine (as well as other vaccines) (h) (discovered Staphylococcus, Streptococcus and Pneumococcus) (i) [Louis Pasteur (Google Search)] [Louis Pasteur (1822-1895) (Access Excellence)] [index] (18) Koch, Robert (late 1800s, early 1900s) (a) Identified the bacteria that cause anthrax, tuberculosis, cholera (b) Contributed significantly to the development of pure culture technique (c) Introduction of agar to microbiology (d) Koch's Postulates, a way of ascribing a particular infectious disease to a particular, causing microorganism

(e)

[Robert Koch (Google Search)] [Robert Koch (1843-1910) (Medicine Through Time)] [index] (19) Semmelweis, Ignaz (mid-late 1800s) (a) Instituted hand washing as a means of minimizing surgical infection (a means of aseptic technique) (b) "Recognized a connection between autopsies and puerperal (childbed) fever. Many physicians went directly from performing autopsies to examining women in labor without so much as washing their hands. When Semmelweis attempted to encourage more sanitary practices, he was ridiculed and harassed until he had a nervous breakdown and was sent to an asylum. Ultimately, he suffered the curious irony of succumbing to an infection caused by the same organism that produces puerperal fever." (c) [Ignaz Semmelweis (Google Search)] [index] (20) Lister, Joseph (mid-late 1800s) (a) Building on the work of Pasteur (anti-spontaneous generation) and Semmelweis (aseptic technique), Lister instituted the use of chemical antimicrobials for the "sanitization" of objects that come into with surgical wounds (b) Considered the "father of antiseptic surgery" (c) [Joseph Lister (Google Search)] [index] (21) Jenner, Edward (late 1700s) (a) Use of cowpox virus to vaccinate against smallpox virus (b) [Edward Jenner (Google Search)] [index] (22) Flemming, Alexander (early 1900s) (a) Discovered penicillin, an antibiotic (b) [Alexander Flemming (Google Search)] [index] (23) Chemotherapy (a) Chemotherapy is the treatment of disease using chemicals istered to the diseased body (b) [antimicrobial therapy (MicroDude)] [index] (24) Antibiotic (a) A kind of antibacterial chemotherapeutic derived from natural sources (e.g., other bacteria) (b) [antimicrobial therapy (MicroDude)] [index] (25) Molecular genetics (a) In addition to the germ theory of disease, microorganisms have served as important biochemical and genetic model systems (b) That is, typically it is easier to study things in microorganisms than in larger organisms because microorganisms generally are cheaper and easier to work with, plus share many important characteristics with larger organisms (c) For example, understanding the molecular role of DNA in the hereditary process occurred as a consequence of studies employing microorganisms (indeed, Watson, of Watson and Crick, studied the viruses of bacteria) (d) [Recombinant DNA and engineering, DNA technology (MicroDude)] [index] (26) Molecular biology (a) Molecular biology is a field that evolved from molecular genetics and microbiology (b) Molecular biology (e.g., genetic engineering) is a series of techniques including such things as gene cloning and DNA sequencing (which are techniques that have traditionally employed microorganisms in their implementation) (c) These are very important tools which are serving to revolutionize how people to and what they can do in biology and medicine (including microbiology) (d) For example, entire genomes of certain microorganisms (a number growing monthly) have been completely sequenced (e) [molecular biology (MicroDude)] [index]