Lecture 1

Question 1

describe the 3 domains of life and the main microbial groups

Answer 1

• bacteria : single-celled, prokaryotic organisms (no nucleus)
  E. coli, Staphylococcus aureus
• archaea : also single-celled and prokaryotic, but have distinctive rRNA sequences, cell walls, and membrane lipids.
  Methanogens (produce methane), halophiles (live in salty environments).
• eukarya : fungi, eukaryotic (have a nucleus); can be unicellular (yeast) or multicellular (molds, mushrooms).
  Saccharomyces cerevisiae, Penicillium.

Question 2

what are microbes

Answer 2

• invisible to the naked eye
• can typically survive as single cells

Question 3

what are viruses

Answer 3

• particles, not cells
• can’t metabolize on their own
• not alive -> rely on other organisms (not cellular)
• made of DNA or RNA inside a protein coat.

Question 4

what is spontaneous generation

Answer 4

• life arises spontaneously from non-living matter
• abiogenic origin of life due to vital force
• aligned well with religious beliefs
• very few others argued that the source of living organisms was other living organisms
• biogenic origin of life

Question 5

how was spontaneous generation refuted by redi

Answer 5

• francesco redi, italian physician 1626-97
• maggots were believed to arise from meat
  exp.
• uncovered jar of meat = maggots on meat
• sealed jar of meat= no maggots
• jar covered with gauze = maggots on gauze

Question 6

how was spontaneous generation refuted by pasteur

Answer 6

• louis pasteur, french chemist (1822-95)
• swan neck flash experiments defeated the theory of spontaneous generation
• some of pasteurs preparations remain sterile to this day
• support for germ theory and showed that microbes are everywhere
• paved the way for establishment of sterilization and pasteurization process
• neck intact = airborne microbes are trapped at base and broth is sterile
• neck on second sterile flask if broken = growth occurs

Question 7

how was spontaneous generation refuted by medical microbiology

Answer 7

• robert kuch, german physician 1843-1910
• demonstrated the link between microbes and infectious disease
• identified causative agents of anthrax and tuberculosis
• awarded the 1905 nobel prize for isolating and identifying the causative agent of tuberculosis using koch’s postulates
• m. tuberculosis, b. anthracis, v. cholerae

Question 8

describe the germ theory of disease and name the key experiments that led to its acceptance

Answer 8

• disease is caused by invisible living creatures
• lucretius (95-55 BC), roman poet and philosopher
• Fracostoro (1546) - italian physician
• each disease is characterized by a certain germ
• infection involves propagation of this germ in host tissues

Question 9

what is miasma

Answer 9

• roman times until 1860s
• disease is caused by toxic vapors, natural disasters, astrological disturbances

Question 10

what is koch’s postulates

Answer 10

1. the suspected pathogen must be present in all cases of the disease and absent from healthy animals (microscopy, staining)
2. the suspected pathogen must be grown in pure culture (laboratory culture) - streak agar plate with sample
3. cells from a pure culture of the suspected pathogen must cause disease in a healthy animal (experimental animals)
4. the suspected pathogen must be reisolated and shown to be the same as the original (laboratory reisolation and culture)

Question 11

who is robert hooke

Answer 11

• british naturalist and architect (1635-1703)
• popularized microscopes and described microscopic organisms in Micrographia (1665)
• first person to see/ describe cells

Question 12

describe the discovery of microbes

Answer 12

• antonie van leeuwenhoek - dutch tailor and haberdasher (1632-1723)
• the father of microbiology
• built microscopes superior to any previous and for the next 150 yrs
• up to 300x magnification
• allowed for visualization of bacteria or animalcules

Question 13

what did martinus beijerinck do

Answer 13

• environmental microbiology
• dutch microbiologist 1851-1931
• isolated and identified tobacco mosaic virus
• realized it was infectious, but smaller than a bacterium and coined the term virus
• described nitrogen fixation and isolated symbiotic nitrogen fixing bacteria from plant root nodules

Question 14

what did sergei winogradsky do

Answer 14

• russian chemist/ microbiologist 1856-1953
• discovered chemolithotrophy and autotrophy (nitrification, sulfide oxidation, iron oxidation)
• isolated many lithotrophic and autotrophic microbes
• developed winogradsky columns to enrich lithotrophic microbes