Chapter 1 History

Question 1

Antonie van Leeuwenhoek

Answer 1

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

Question 2

Spontaneous Generation and John Baptist van Helmont

Answer 2

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

Question 3

Francesco Redi

Answer 3

1626-1697: showed that maggots in decaying meat were offspring of flies

argued against spontaneous generation

Question 4

Lazzaro Spallanzani

Answer 4

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

Question 5

Louis Pasteur

Answer 5

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

Question 6

Robert Koch

Answer 6

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

Question 7

Koch’s Postulates (1884)

Answer 7

1. microbe is found in all cases of disease, but absent from healthy individuals
2. the microbe is isolated from the diseased host and grown in pure culture
3. when the microbe is introduced into a healthy susceptible host, the same disease occurs
4. the same strain of microbe is obtained from the newly diseased host

Question 8

Golden Age of Microbiology: 1857-1914

Answer 8

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

Question 9

pure culture

Answer 9

culture grown from a single parental cell

Question 10

autoclave

Answer 10

steam pressure device used to sterilize materials for the controlled study of microbes

Question 11

John Tyndall

Answer 11

1820 - 1893

showed that repeated cycles of heat were necessary to eliminate spores formed by certain kinds of bacteria

Question 12

antiseptic agent

Answer 12

chemical that kills microbes

1847: doctors start washing their hands with chlorine, mortality rates decrease

Question 13

Alexander Fleming

Answer 13

1881 - 1955

invented penicillin to kill bacteria (1929)

Question 14

Edward Jenner

Answer 14

1798 - observed milk maids with cow pox do not get small pox;

deliberately infected patients with matter from cowpox lesions - vaccination

Question 15

Vaccination

Answer 15

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

Question 16

Sergei Winogradski

Answer 16

(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

Question 17

Rosalind Franklin

Answer 17

(1920 - 1958)

discovered structure of coiled RNA using x-ray crystallography

double helical structure of DNA

Question 18

Martinus Beijerinck

Answer 18

(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

Question 19

Nitrogen Fixation

Answer 19

The process by which bacteria and archaea fix nitrogen (N2) by reducing it to ammonia (NH3), the form of nitrogen assimilated by plants

Question 20

diazotrophy

Answer 20

converting N2 –> NH3 (ammonia)

Question 21

geochemical cycling

Answer 21

depends on bacteria and archaea that cycle nitrogen, phosphorus, and other minerals throughout the biosphere

Question 22

chemolithotrophs (lithotrophs)

Answer 22

metabolize inorganic minerals such as ammonia instead of organic nutrients used by the microbes isolated by Koch

Question 23

Dark side of the golden age

Answer 23

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

Question 24

Endosymbiosis Theory

Answer 24

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

Question 25

Lynn Margulis

Answer 25

(1938 - 2011)

proposed the theory of endosymbiosis; implied a non-linear development and recombination of life forms

polyphyletic development: multiple ancestry of living species

1966: idea rejected by over 10 journals

widely accepted in the 1980s with support of sequencing data

Question 26

Carl Woese

Answer 26

Research scientist at the University of Illinois, Champaign-Urbana

Born in 1923 (in Syracuse, NY)

Realized that:

1. all living organisms contain ribosomes
2. these could be sequenced
3. used to generate a tree of life, to show how organisms are related

his discovery replaced the classification scheme of 5 kingdoms to the 3 domains: Bacteria, Archaea, and Eukarya

PICTURE: length of branch approximates the time of divergence from the last common ancestor