Chapter 1 History Flashcards
(27 cards)
Antonie van Leeuwenhoek
1632-1723: first to observe single celled microbes
viewed tiny animalcules from his teeth and noticed that organisms disappeared after drinking really hot coffee
1683: first microscope with lens, sample holder, focus knob, sample movwer

Spontaneous Generation and John Baptist van Helmont
theory that living creatures arise spontaneously
John Baptist van Helmont: believed that if a dirty shirt was placed in a vessel with wheat then after 21 days a mouse would arise
Francesco Redi
1626-1697: showed that maggots in decaying meat were offspring of flies
argued against spontaneous generation

Lazzaro Spallanzani
1729 - 1799: sealed flasks do not grow microorganisms - critics of him argued that it was anaerobic (lacked access to oxygen)
cell fission: cells arise by splitting from pre-existing cells

Louis Pasteur
1822-1895
debunked spontaneous generation
used the swan neck flask that allowed air through but no dust –> no microbes grew
also discovered that fermentation is caused by yeast
discovered chirality (some molecules exist in two forms mirrored by symmetry)
improved on Spallanzani’s experiment
discovered that weakened form of disease gives immunity
1879 (?): vaccine for rabies

Robert Koch
1843-1910: German doctor
first to grow pure cultures and discover causative agents of tuberculosis, asiatic cholera, and anthrax
Koch’s Postulates: set of 4
demonstrated the chain of infection or transmission of disease
Koch’s Postulates (1884)
- microbe is found in all cases of disease, but absent from healthy individuals
- the microbe is isolated from the diseased host and grown in pure culture
- when the microbe is introduced into a healthy susceptible host, the same disease occurs
- the same strain of microbe is obtained from the newly diseased host
Golden Age of Microbiology: 1857-1914
Koch and Pasteur isolate and study individual microbes in pure culture
Physiological characteristics of a microorganism could be researched in great detail
Identify known disease-causing microbes an determine the identity of microbes isolated from patients.
Sanitation shows + correlation with mortality
Gram stain developed
pure culture
culture grown from a single parental cell
autoclave
steam pressure device used to sterilize materials for the controlled study of microbes
John Tyndall
1820 - 1893
showed that repeated cycles of heat were necessary to eliminate spores formed by certain kinds of bacteria
antiseptic agent
chemical that kills microbes
1847: doctors start washing their hands with chlorine, mortality rates decrease
Alexander Fleming
1881 - 1955
invented penicillin to kill bacteria (1929)
Edward Jenner
1798 - observed milk maids with cow pox do not get small pox;
deliberately infected patients with matter from cowpox lesions - vaccination
Vaccination
common in Turkey in 1700s; introduced in Europe by Lady Mary Montagu
Jenner did small box vaccination in 1798
Pasteur discovered that a weaked strain of microbes could transfer immunity to patient
Sergei Winogradski
(1856 - 1953)
Winogradski Column: glass tube containing mud (source of wetland bacteria) mixed shredded newsprint (organic carbon source) and calcium salts of sulfate and carbonate (inorganic carbon source for autotrophs)
Top: cyanobacteria conduct photosynthesis and use light energy to split water and produce molecular O2
Below: purple sulfur bacteria use photosynthesis to split hydrogen sulfide to produce sulfur
At the bottom: (O2 exhausted) bacteria reduce (donate electrons) alternative electron acceptors such as sulfate; these bacteria produce hydrogen sulfide and precipitate iron

Rosalind Franklin
(1920 - 1958)
discovered structure of coiled RNA using x-ray crystallography
double helical structure of DNA
Martinus Beijerinck
(1851 - 1931)
discovered lithoautotrophy: using CO2 for carbon, inorganic chemicals for energy
Beggiotoa (sulfure eating bacterium)
first to observe bacteria living as endosymbionts with plants
suspected that microbes may be converting atmospheric nitrogen (N2) into usable form ammonia (NH3) rather than using NH3
concluded that because the agent of disease passed through a filter that retained bacteria, it could not be a bacterial cell
observed rhizobial endosymbiosis

Nitrogen Fixation
The process by which bacteria and archaea fix nitrogen (N2) by reducing it to ammonia (NH3), the form of nitrogen assimilated by plants
diazotrophy
converting N2 –> NH3 (ammonia)
geochemical cycling
depends on bacteria and archaea that cycle nitrogen, phosphorus, and other minerals throughout the biosphere
chemolithotrophs (lithotrophs)
metabolize inorganic minerals such as ammonia instead of organic nutrients used by the microbes isolated by Koch
Dark side of the golden age
Microbes classified by physiology or morphology
DNA sequence relatedness not considered
Evolutionary relations elusive
HOWEVER….20th century was considered the “Second Golden Age”, the molecular revolution
Endosymbiosis Theory
Mitochondria were bacteria.
Chloroplasts were cyanobacteria.
They were infected or eaten by a pre-eukaryotic organism and ended up living together inside –> endosymbiosis
Provided plants and animals with their current metabolic capabilities
proposed by Lynn Margulis

