Exam 1 Flashcards
(43 cards)
Alexander Fleming
- 1929
- microbiologist studying bacteria
- made an accidental discovery: left agar plates for a few days when on vacation. When he came back, he notices a greenish fungal contaminate on one (careless and untidy lab)
- colonies were replaced with GHOST COLONIES
- isolated the fungus, found it could kill bacteria; identified the fungus as PENICILLIUM (1st antibiotic)
- then, in the 1940s, chemists isolated penicillin and there was a boom in antibiotics which led to closure of TB hospitals (problem: antibiotic resistance)
Marinus Beijerinck
~1900
- botany professor in Holland
- formed the Enrichment culture technique –> microorganisms are isolated by using highly selective media and incubation conditions that favor a particular metabolic group of organisms
- isolated pure cultures
- Described the first virus and principles of virology (“mosaic disease” of tobacco) –> discovered it was not a bacterium bc it passes through a filter that retains bacteria
Robert Koch
- 1896
- physician interested in studying diseases in animals. progressed to studying disease in humans
- worked with ANTHRAX (disease affecting livestock)
- decided to isolate the bacteria in the blood and grow in a pure culture, then transfer to a healthy animal –> proved that Bacillus anthracis is the cause of anthrax
- problem with this was lack of technology to isolate cultures. Solution: Agar and a petri dish
- identified cause of TB and cholera (using Koch’s methods, other researchers identified what bacteria caused diseases typhus, tetanus, and the plague)
Joseph Lister
- 1865
- came across writings of Semmelweis
- started sterilizing knives using phenol(carbolic acid) as an antiseptic => drastically reduced infection rates
- he was laughed at and he shrugged it off
Edward Jenner
- late 1700s
- worked with cowpox virus
~ cowmaids has a lower incidence of smallpox; he hypothesized that they were being exposed to cowpox
~ he tried injecting people with cowpox. discovered cowpox and smallpox not that similar = provided little immunity - didn’t keep good records => little impact
- came up with term VACCINATION
Louis Pasteur
- 1860s
- “Father of Microbiology”
- invented swan-necked flask => drove the final stake through spontaneous generation (it was particles in the air leading to microbial growth)
- made the germ hypothesis into the GERM THEORY
- invented rabies vaccine & worked with chicken cholera
- invented pasteurization
Ignaz Semmelweis
- 1840
- in charge of hungarian hospital
- women were dying from Puerperal fever (child bed fever)
~ deaths occurring more often with interns (would go straight from corpses to women giving birth)
~ began washing hands => reduced rates - idea was laughed at & he disappeared
John Snow
- 1854
- 1st Epidemiologist
- cholera outbreaks (decided to prevent rather than treat)
- map of cholera deaths & water pumps
- took handle off contaminated pump => disease dwindled
Anton van Leeuwenhoek
- 1680
- invented 1st microscope
- “wee animalcules”
~ published pictures - put into question the hypothesis of spontaneous generation
Describe the controversy surrounding “spontaneous generation”. When and how was it disproved for microorganisms? What was the alternative hypothesis which later became a theory?
It was a common belief that life arose spontaneously from nonliving material (began with a man noticing flies on meat that was left out and thought the flies came from the meat). Pasteur was a powerful opponent to spontaneous generation. It was disproved in the 1860s by the swan-necked flask (Louis Pasteur); he was able to show that the growth was due to particles in the air. The alternative hypothesis was the germ hypothesis (disease comes from a “germ” which refers to any type of microorganism) that Pasteur made into the germ theory (growth and reproduction of microorganisms causes disease)
Koch’s postulates
Steps needed to demonstrate microbial cause of disease
1) ASSOCIATION - the microbe must be present in every case of the disease & absent when there is no disease
2) ISOLATION - the microbe must be isolated in pure culture
3) CAUSATION - innoculation of healthy animal with pure culture should cause disease
4) REISOLATION - you should be able to isolate the same microbe from the newly sick animal
~ Koch was able to identify 25-30 diseases using this method
importance of pure culture techniques in microbiology
Pure culture: a population of identical cells (single species or strain of bacteria)
Pure culture techniques allow isolation of bacteria by use of solid media (agar) incubated in air in a petri dish; it is important because it allows the study of cultural, morphological, and physiological characteristics
two inventions by Koch’s lab that allowed development of pure culture techniques
1) petri dish (developed by Richard Petri, associate of Koch in 1887)
2) growth media (seaweed agar). employed liquid nutrient solutions solidified with gelatin, and later with agar
ways of staining bacteria to improve visibility under microscope
disease and disease-causing organism that killed more than a quarter of the population of Europe between 1346-1350
Bubonic plague “black death” caused by bacteria Yersinia Pestis which is transmitted by a flea biting a rat and then biting a human.
Led to quarantine.
two examples of biological warfare used prior to the 1800s
1) Dead plague victims were catapulted over a wall as biological warfare when the Mongols attacked Caffa, Ukraine
2) European settlers gave Native Americans blankets contaminated with smallpox
three early attempts at immunization
1) Edward Jenner’s attempt to create a smallpox vaccination by injecting people with cowpox
2) Rabies vaccine by Louis Pasteur; he injected a kid who had been bitten with a weakened virus (weakened by heating it up) & he survived
3) 900 A.D. Chinese taking scabs from small pox victims, powder it, and use a straw to blow it into the nostrils of children
4) chicken cholera (Pasteur) - injected people with the old culture and nothing happened. When he injected them with the new culture, the ones who had been injected with the old culture didn’t get sick; the ones who hadn’t been injected with the old culture got sick
describe the importance of immunization and role of herd immunity in preventing disease in population. What myth has resulted in low immunization rates and disease resurgence in the US?
Immunization protects from disease. Herd immunity is if you vaccinate enough of the population, everyone is protected. Herd immunity protects those who are unable to be vaccinated. The myth that began the anti-vaccination movement was that vaccinations cause autism (small study on 12 kids already showing signs of autism done by British doctor Andrew Wakefield in 1998).
describe at least five behaviors or practices that have contributed to increased antibiotic resistance in microbes
1) over-prescription by physicians (antibiotics for viruses)
2) over the counter availability of antibiotics
3) not taking the entire treatment (leaves less sensitive strains)
4) inclusion of antibiotics in livestock feed (animals use 8x as much antibiotics => regulations)
5) too small of dose
describe the three basic groups (domains) of organisms identified by rRNA sequence analysis and how these differ from the classical five kingdom classification system
- 3 groups: bacteria, archaea (single celled), eukarya
- Universal phylogenetic tree of life is based on gene sequences; the gene picked was for rRNA
~ ribosome has two subunits
~ prokaryotes have ribosomes 70s in size; two subunits are 50s and 30s (in the 30s, there is a 16s rRNA segment)
~ eukaryotes have ribosomes 80s in size; two subunits are 60s and 40s (in the 40s, there is a 18s rRNA) - the classical five kingdom (whittaker): prokaryotae (monera), protista, fungi, plantae, animalia. Based on cell type (prokaryote or eukaryote), number of cells (unicellular or multicellular), cell wall or not, produce food or not
describe the characteristics that typically distinguish eukaryotic and prokaryotic organisms. What are the definitive characteristics that separate the two groups?
Prokaryotes:
- no membrane bound nuclei
- cell wall
- storage granules
- simple organelles
- lack of additional compartmentalization
- vacuoles and cytoplasm pressed against plasma membrane
Eukaryotes:
- cell membrane
- plant/fungi: cell wall
- double membrane bound nucleus
- Endoplasmic reticulum (1) rough: proteins 2) smooth: lipids, polysaccharides)
- golgi apparatus
- mitochondria
- lysosomes
- mitochondria
- plant: chloroplasts (thylakoid, granna, chlorophyll)
- vacuole
- microtubules
- microfilaments
- structure of chromosomal DNA
- membrane bound organelles
name the genus of one of the two ginormous prokaryotes discovered in the past few years
- epulopiscium fisheloni (from gut of surgeonfish)
- Thiomargarita namibiensis (in marine sediments)
describe the characteristics that typically distinguish eukaryotic and prokaryotic organisms. What are the definitive characteristics that separate the two groups?
Prokaryotes:
- no membrane bound nucleus
- single circular dsDNA chromosome (haploid)
- no wasted space
- super coiled
- 0.4 microns is as small as it can be
- chromosome is 4x10^6 bp
- lack of additional compartmentalization
- vacuoles and cytoplasm pressed against plasma membrane
Eukaryotes:
- double membrane bound nucleus
- many linear strands of double stranded DNA (haploid, diploid, or polyploid)
- DNA is packaged around histone proteins => nucleosomes (many nucleosomes form a chromosome)
- lots of information (100 to 10,000x as much)
- lots of wasted space - introns (non-coding region)
- any cell division has to involve mitosis
- mitochondria
- chloroplasts
- structure of chromosomal DNA
- membrane bound organelles
describe the chemical and physical structure of prokaryotic and eukaryotic membranes
cytoplamic membranes:
- consist of phospholipid bilayer (glycerol backbone attached to a phosphate and fatty acids attached to hydroxyl groups on glycerol backbone)
~ hydrophobic tail pointing inward; hydrophilic head pointing outward
- transmembrane proteins
1) uniporters
2) symporters
3) antiporters
(changes in protein conformation facilitate transport)
define “protein conformation”. Describe its importance and what factors influence it
- protein conformation is the change in protein shape
- changes in protein conformation facilitate transport; can occur by interaction with environment
- chemical composition of protein gives it its function
- influences:
pH
water matrix
anions and cations
effects folding and function
chaperone proteins
