exam #1 Flashcards
microbe
living organism that requires a microscope to be seen
most microbes consist of how many cells?
a single cell
how big are microbes?
0.2 um to just a few mm
each microbe contains in its own genome the capacity to what?
reproduce its own kind
is a virus considered a microbe?
yes, even though it doesn’t perfectly fit the definition
prokaryote
-type of microbial organism
-cells lacking a nucleus
-bacteria and archaea
eukaryote
-type of microbial organism
-cells with a nucleus
-algae, fungi, and protists
type of microbial organisms: prokaryotes, eukaryotes, and ?
viruses and prions (acellular entities)
three domains of life
-all come from common ancestor
-bacteria = prokaryote
-archaea = prokaryote
-eukarya = algae and plants, fungi and animals, protists = eukaryotes
order these form least to most recent
-microbes observed under a microscope
-food and drink are produced by microbial fermentation
-koch’s postulates are established
-first immunization (smallpox)
-first microbial genome sequenced
-penicillin antibiotic first isolated
-first mRNA vaccine approved (covid)
-crispr-cas9 bacterial self-defense mechanism is used for programmable gene editing
-food and drink are produced by microbial fermentation
-microbes observed under a microscope
-first immunization (smallpox)
-koch’s postulates are established
-penicillin antibiotic first isolated
-first microbial genome sequenced
-crispr-cas9 bacterial self-defense mechanism is used for programmable gene editing
-first mRNA vaccine approved (covid)
Robert Hooke (1635-1703)
-built the first _____
-used it to observe ____
-coined the term ____
-published micrographia, the first manuscript that illustrated ____
-built the first compound microscope
-used it to observe mold
-coined the term “cell”
-published micrographia, the first manuscript that illustrated objects observed with a microscope
Antonie can Leeuwenhoek (1632-1723)
-built ______, complete with sample holder and ___ adjustment
-first to observed ____: he called them ____
-built single-lens magnifiers, complete with sample holder and focus adjustment
-first to observed single-celled microbes: he called them “small animals”
spontaneous generation
theory that living organisms could arise without parents
Francesco Redi (1660s)
showed that maggots in decaying meat were ____= refuted ___
showed that maggots in decaying meat were the offspring of flies = refuted spontaneous generation
Lazzaro Spallanzani (1760s)
showed that a sealed flask of meat broth sterilized by boiling ______ = refuted ____
showed that a sealed flask of meat broth sterilized by boiling failed to grow microbes = refuted spontaneous generation
Louis Pasteur (1822-1895)
-showed that a broth boiled in a swan-neck flask _____, despite being exposed to air = refuted ____
-discovered the microbial basis of ____
-showed that a broth boiled in a swan-neck flask remained free of microbial growth, despite being exposed to air = refuted spontaneous generation
-discovered the microbial basis of fermentation
Pasteur experiment
1. the broth was boiled to ___
2. after a year, ____ and the old ones were trapped in curve
3. the flask was tipped to allow the ____
4. microbes quickly ____
- the broth was boiled to kill all microbes
- after a year, no microbes appeared and the old ones were trapped in curve
- the flask was tipped to allow the broth to reach the microbes
- microbes quickly multiplied
germ theory of disease
suggests that many diseases are caused by microbes
Robert Koch (1843-1910)
-German physician
-founder of the _____ of microbiology
-applied his methods to the study of several ____
-German physician
-founder of the scientific method of microbiology
-applied his methods to the study of several lethal diseases
working with anthrax, ____ demonstrated an important principle of epidemiology: ____
working with anthrax, Koch demonstrated an important principle of epidemiology: the chain of infection, or transmission of disease
to prove that mycobacterium caused TB, ___ needed to establish a ____ of the microbes being studied
to prove that mycobacterium caused TB, Koch needed to establish a pure culture of the microbes being studied
Koch’s colleagues contributed important tools for the generation of _____
-Angelina and Walther Hesse = ____
-Julius Petri = ____
Koch’s colleagues contributed important tools for the generation of pure cultures
-Angelina and Walther Hesse = agar to solidify culture medium
-Julius Petri = double-sided Petri dish
Koch’s postulates
- the microbe is found in all cases of the disease but is 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
immunization
-observation: milkmaids had ___ to smallpox
-hypothesis: ____ due to exposure to ____
-experiment: Edward ____ (1749-1823) ___ with material he collected from cowpox lesions
—the practice of cowpox inoculation was called ____
-observation: milkmaids had natural immunity to smallpox
-hypothesis: immunity due to exposure to cowpox infected cows
-experiment: Edward Jenner (1749-1823) deliberately infected patients with material he collected from cowpox lesions
—the practice of cowpox inoculation was called vaccination
_____ developed the first vaccines based on _____ strains of microbes: ____ and ____
Louis Pasteur developed the first vaccines based on attenuated (weakened) strains of microbes: fowl cholera and rabies
immunization
the stimulation of an immune response by deliberate inoculation with an attenuated pathogen
(1847) Ignaz ___ ordered doctors to ____ with chlorine, an ___ agent = mortality rates rose/fell
(1847) Ignaz Semmelweis ordered doctors to wash their hands with chlorine, an antiseptic agent = mortality rates fell
(1865) Joseph ___ developed ___ to treat wounds and clean surgical instruments
(1865) Joseph Lister developed carbolic acid to treat wounds and clean surgical instruments
in the twentieth century, ____ surgery was developed
-environments completely ____-free
in the twentieth century, aseptic surgery was developed
-environments completely microbe-free
(1929) _____ discovered that ____ mold generated a substance that kills bacteria
(1929) Fleming discovered that Penicillium mold generated a substance that kills bacteria
(1941) Florey and Chain purified ____
-_____ quickly became the first commercial ____ used to save human lives
(1941) Florey and Chain purified penicillin
-penicillin quickly became the first commercial antibiotic used to save human lives
microbes cycle the many nutrients essential for life, including all global __ and most of the __ in earth’s atmosphere
-less than 0.1% of all microbial species can be ___
-the remainder make up the majority of earth’s ___
microbes cycle the many nutrients essential for life, including all global N2 and most of the O2 in earth’s atmosphere
-less than 0.1% of all microbial species can be cultured in the laboratory
-the remainder make up the majority of earth’s biosphere
bacteria are important for ____ cycling
bacteria are important for geochemical cycling
endosymbionts
microbes that partner with a larger host organism
Linnaeus (1707-1778) called the microbial world ___
-early taxonomists faced two challenges as they attempted to classify microbes
1. ___ of the microscope was too low = overcome via advances in ___
2. microbial species are ___ = 95% similarity of ___ sequence
Linnaeus (1707-1778) called the microbial world “chaos”
-early taxonomists faced two challenges as they attempted to classify microbes
1. resolution of the microscope was too low = overcome via advances in biochemistry and microscopy
2. microbial species are hard to define = 95% similarity of DNA sequence
(1977) ___ studied recently discovered ___that live in hot springs and produce methane
-analysis of their ____ revealed that these prokaryotes were a ___
-called these new prokaryotes the ___
(1977) Woese studied recently discovered prokaryotes that live in hot springs and produce methane
-analysis of their 16S rRNA revealed that these prokaryotes were a distinct form of life
-called these new prokaryotes the archaea
____ discovery replaced the classification scheme of five kingdoms with ___ groups called ___
-list them
Woese’s discovery replaced the classification scheme of five kingdoms with three equally distinct groups called domains
-bacteria, archaea, and eukarya
(1938-2011) ___ proposed that eukaryotic organelles, such as mitochondria and chloroplasts, evolved by ____ from prokaryotic cells ___ by pre-eukaryotes
(1938-2011) Margulis proposed that eukaryotic organelles, such as mitochondria and chloroplasts, evolved by endosymbiosis from prokaryotic cells engulfed by pre-eukaryotes
advances in biochemistry and microscopy revealed the fundamental structure and function of ____
cell membranes and proteins
the revelation of the ___ and ___ structures led to the discovery of the ___ of model organisms
the revelation of the DNA and RNA structures led to the discovery of the genetic programs of model organisms
a heat-stable bacterial DNA ____ was used for amplifying DNA via the ____
a heat-stable bacterial DNA polymerase was used for amplifying DNA via the polymerase chain reaction (PCR)
the size at which objects become visible depends on the ___ of the observer’s eye
the size at which objects become visible depends on the resolution of the observer’s eye
resolution
the smallest distance by which two objects can be separated and still be distinguished
detection
the ability to determine the presence of an object
magnification
an increase in the apparent size of an image to resolve smaller separations between objects
light is part of the spectrum of
electromagnetic radiation
for electromagnetic radiation to resolve an object, 3 conditions must exist
- contrast between object and its medium
- wavelength smaller than the object
- magnification
absorption
the photon’s energy is acquired by the absorbing object
reflection
wavefront bounces off the surface of an object
scattering
wavefront interacts with an object smaller than the wavelength of light
refraction
-our goal
-bending of light as it enters a substance that slows its speed
bright field microscopy
-what it is
-how to increase resolution
-generates a dark image of an object over a light background
-to increase resolution: use shorter-wavelength light, use immersion oil, use wider lens closer to specimens
immersion oil has a ____ comparable to that of the ____ (n=1.5)
-it minimizes the _____ by refraction and makes it possible to reach 100x _____ with minimal ___
immersion oil has a refractive index comparable to that of the lens (n=1.5)
-it minimizes the loss of light rays by refraction and makes it possible to reach 100x magnification with minimal distortion
higher ___ increases resolution
numerical aperture (10x v.s 100x)
compound microscope
-parts
-total magnification (TM)
compound microscope: a system of multiple lenses designed to correct or compensate for aberration
-ocular lens, objective lens, needs to be parafocal (focus doesn’t change when lens switches)
-total magnification: magnification of the ocular multiplied by the objective
wet mount
-advantages
-disadvantages
wet mount preparation: a simple way to observe microbes by placing them in a drop of water on a slide with a coverslip
-advantages: observation of cells in natural state
-disadvantages: little contrast between cell and background and sample may dry out quickly
the detection and ___ of cells under a microscope are enhanced by: fixation and staining
-give definitions
the detection and resolution of cells under a microscope are enhanced by: fixation and staining
-fixation: cells are made to adhere to a slide in a fixed position
-staining: cells are given a distinct color
simple stain
-what is most commonly used?
adds dark color specifically to cells, but not to the external medium or surrounding tissue
-methylene blue
differential stain
-what is most commonly used?
stains one kind of cell but not another
-gram stain
gram stain (+ vs -)
-gram positive bacteria retain the crystal violet stain because of their thicker cell wall
-gram negative bacteria do not, thin cell wall
acid-fast stain
carbofluchsin used to stain mycobacterium species
spore stain
malachite green use to detect spores of bacillus and clostridium
negative stain
colors the background, which makes capsules more visible
fluorescence microscopy
the specimen absorbs light of a defined wavelength and then emits light of lower energy, thus longer wavelength = the specimens fluoresces
fluorophore
-fluorescent chemical compound
-cell specificity can be determined by: chemical affinity, labeled antibodies, DNA hybridization, gene fusion reporter
immunofluorescence microscopy determines what?
co-localization of labeled proteins
electron microscopy
the foremost tool for observing the shapes of macromolecular structures
X-ray crystallography or X-ray diffraction analysis
-tool of choice for atom-level detail of a macromolecule
-protein resolution
-for samples that can be crystallized (limitation), X-ray diffraction makes it possible to fix the position of individual atoms in a molecule
electron microscopy
-electrons behave like ___: very high ____and allow very great ___
-sample must absorb ____: coated with heavy ___
-electron beam and sample are in a ___: lenses are ___ fields
-electrons behave like light waves: very high frequency and allow very great resolution
-sample must absorb electrons: coated with heavy metal
-electron beam and sample are in a vacuum: lenses are magnetic fields
transmission electron microscopy
-electrons pass through specimen
-reveals internal structures in 2D
-can look at thin slices
scanning electron microscopy
-electrons scan the specimen surface
-reveals external features in 3D
-electrons bounce off surface of specimens and reflect back
