Exam 1 Flashcards
Ergotism
Cause: mold Claviceps purpurea - produces toxic alkaloids
Symptoms: spasms, itching, mania, psychosis
Proposed explanation for bewitchment
Van Helmont
recognized that fermentation gave rise to gas and alchohol
Van Leeuwenhoek
invented simple microscope
Kirchner
Monk
first to claim to see “invisible worms” with microscope
Pasteur
researched heat preservation methods
described microbio of lactic acid fermentation
coined aerobic and anaerobic by investigation alch production of yeast
ended debate on spontaneous generation (via swan neck flask exp.)
used attenuated (less virulent) strain as vaccine for chicken cholera
injected Joseph Meister with “aged” spinal cord containing rabies virus
Koch
- worked with anthrax, wrote paper pointing to a bacterium as the cause of this disease = validation of germ theory of disease (some diseases are caused by microorgs)
- pure culture studies made possible (potato slices)
- discovered cause of TB and cholera
- Koch’s postulates
Koch’s postulates
- microorg must be found in abundance in all orgs with disease and not in healthy orgs
- microorg must be isolated from diseased org and grown in pure culture
- culture should cause disease when put into healthy org
- microorg must be reisolated from infected person and identified as identical to original
Walter Hesse
Koch’s associate
First to use agar to isolate pure culture
Actually was his wife who suggested agar
Lister
Observed that people survived surgery but died of “ward fever”
Proposed that microbes in air and on doc’s hand caused post-op infections
introduced thorough cleaning of wound then covering with phenol-saturated cloth
Machine that pumped mist of phenol was used during operations
lactic acid fermentation (showed that a specific bacterium caused the lactic acid fermentation in milk)
Ehrlich
Proposes that antibodies contribute to immunity
Shows that they are produced against the plant toxins ricin and abrin
Metchnikoff
discovered macrophages
work with phagocytosis
Twort
discovered bacteriophage (viruses that affect bacteria) accidentally when he noticed that some bacteria on plates became transparent
Transduction
When a bacteriophage inserts a virus into a host, it takes some of the host DNA with it which then is inserted into the next host
Griffith
discovers transformation (genetic alteration via uptake of foreign DNA through cell membrane) in bacteria and est. foundation for molecular genetics Experiment w/ rats
Fleming
Publishes first paper describing penicillin and its effects on gram positive bacteria
Howard Florey & Ernest Chain
Produce extract of penicillin, isolated from Fleming’s culture - show that it can cure infections in animals
Lederberg & Tatum
Describe conjugation in bacteria
Transformation
Genetic alteration via uptake of foreign DNA through cell membrane
Conjugation
Transfer of genetic material (plasmid) between cells by direct cell to cell contact
Crick, Wilkins & Watson
Double helix structure of DNA based on x-ray crystallography done by Rosalind Franklin
Rosalind Franklin
Did x-ray cyrstallography of DNA that lead to the description of the double helix structure by Crick, Wilkins and Watson
Gilbert & Sanger
Develop methods to sequence DNA
Prusiner
Finds evidence that class of infections proteins called prions cause scrapie
Prions
Protein molecules
Not infection, conversion: find prion like orgs in host and convert them to the bad form
Infectious agent composed of protein in a misfolded form
Mullis
Uses the heat stable enzyme from Thermus aquaticus to establish PCR technology
PCR
Polymerase chain reaction
Amplifies a piece of DNA
Acetic acid
pKa 4.75
inhibits gram positive and negative
yeasts and molds tolerant
Jellies
benzoic acid
pKa 4.19 pH range 2.5-4.5 inhibits yeasts and molds and enzymes first antimicrobial premitted in foods jellies
parabens
esterification of benzoic acid pH 3-8 active against yeasts and molds, some bacteria (g+) targets cytoplasmic membrane jams
sorbic acid/sorbates
pKa 4.75
inhibits yeasts, molds, some bacteria
prevents germination of spores of clostridium botulinum
Jam
sodium (NaNO2) and potassium nitrites
curing agents in meats
effective at reduced pH and anaerobic conditions
purpose to inhibit c. botulinum, etc, prevents spore growth
antioxidant
influences flavor, color, lipid oxidation
impacts iron-sulfur clusters (ferredoxins) = reduced ATP production
in acidic environment makes nitrous acid which can make nitric oxide - color fixation in meats
lactic acid bacteria are tolerant
can react with amines to form nitrosamines at high temps = carcinogenic
can oxidize iron to Fe3+ form which cannot bind oxygen (infants)
sulfites
ancient Romans and Greeks effective below pH 4 inhibit DNA replication, enzymes, protein synthesis, damage to cytoplasmic membrane control spoilage in fruits some humans are sensitive to it
