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BMS 212 exam 1 chapters 1-4

Terms in this set (143)

how can microbes be classified?
bacteria, archaea, fungi, protozoa, algae, small multicellular animals
bacteria
prokaryotes that are unicellular and lack nuclei
-typically much smaller than eukaryotes
-their genetic material is condensed into a nucleoid in the cytoplasm
-found everywhere there is sufficient moisture (extremophiles)
-reproduce asexually
-estimated only 10% of species can be cultured in lab
bacterial cell walls contain:
peptidoglycan
fungi
eukaryotic (have membrane bound nucleus)
-obtain food from other organisms
-possess cell walls
-include mold and yeasts
protozoa
single-celled eukaryotes
-live freely in water; some live in animal hosts
-asexual (mostly) and sexual reproduction
most protozoa are capable of locomotion by:
pseudopods, cilia, and flagella
algae
-Unicellular or multicellular
-Photosynthetic
-Simple reproductive structures
-Categorized on the basis of pigmentation, storage products, and composition of cell wall
other pathogens of importance to microbiologists:
parasites, viruses, prions
the smallest pathogens:
prions
Scientists searched for answers to four questions:
-where do microbes come from?
-what causes fermentation?
-what causes disease?
-how can we prevent infection and disease?
Antoni Van Leeuwenhoek
-began making and using simple microscopes (animalcules)
-by the end of the 19th century, these organisms were called microorganisms
some philosophers and scientists of the past thought living things arose from 3 processes:
-asexual reproduction
-sexual reproduction
-nonliving matter
aristotle proposed:
spontaneous generation
Redi's experiments:
flies and 3 jars of meat (1 jar open, 1 closes with a cork, 1 with a cloth on top)
-the flies had to come in contact with the meat to lay their eggs
-as a result, scientists began to doubt Artistotle's theory
-scientists agreed large animals could not arise spontaneously
Spallanzani's experiment concluded that:
microorganisms exist in air, and spontaneous generation of microorganisms does not occur
Spallanzani's experiments tested by:
taking broth and heated it to boiling and then let it cool down
-has 1 flask that was sealed off and 1 left open
-over time, the open one became putrid and cloudy, started to see bacterial growth, smells bad
-the sealed one had no growth, remained translucent, did not putrefy until more time was passed and the cork was removed and then it putrefied and saw growth
Louis Pasteur
father or modern day microbiology
-created swan neck flasks
-boiled broth, steam escapes, allows air to move in and out and any microbes/dust will settle on the bottom of the neck
the scientific method
-observation ---> question
-hypothesis
-hypothesis is tested through experiment(s)
-results prove or disprove hypothesis
accepted hypothesis leads to:
theory/law
disproved hypothesis is:
rejected or modified
the theory of spontaneous generation postulates that living organisms can be derived from:
non-living matter
what causes fermentation?
-spoiled wine threatened livelihood of many grape growers
-some believed air causes this, others insisted living organisms caused this
fermentating grape juice microscopic analysis shows:
juice contains yeasts and bacteria
hypothesis #1
spontaneous fermentation occurs
experiment for hypothesis #1 & #2
day 1: flasks of grape juice are heated sufficiently to kill all microbes
observation for hypothesis #1 & #2
no fermentation; juice remains free of microbes
conclusion to hypothesis #1
reject hypothesis 1
hypothesis #2
air ferments grape juice
conclusion to hypothesis #2
reject hypothesis 2
hypothesis #3
bacteria ferment grape juice into alcohol
experiment for hypothesis #3
flasks of grape juice are heated sufficiently to kill all microbes, the juice in the flask is inoculated with bacteria and sealed
observation for hypothesis #3
bacteria reproduce; acids are produced
conclusion for hypothesis #3
modify hypothesis; bacteria ferment grape juice into acids
hypothesis #4
yeasts ferment grape juice into alcohol
experiment for hypothesis #4
flasks of grape juice are heated sufficiently to kill all microbes, juice in flask is inoculated with yeast and sealed
observation for hypothesis #4
yeasts reproduce; alcohol is produced
conclusion for hypothesis #4
accept it; yeasts ferment grape juice into alcohol
Pasteur's experiments
Led to the development of pasteurization --> process of heating liquids just enough to kill most bacteria
-began the field industrial microbiology
-intentional use of microbes for manufacturing products
Pasteur developed:
germ theory of disease
Robert Koch studied:
causative agents of disease (etiology)
Koch's experiments:
-simple staining techniques
-first photomicrograph of bacteria
-first photograph of bacteria in diseased tissue
-techniques for estimating bacterial number in a solution
-use of steam to sterilize growth media
-use of petri dishes
-bacteria as distinct species
Koch's Postulates
1.) the microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms
2.) the microorganism must be isolated from diseased organism and grown in pure culture
3.) the cultured microorganisms should cause disease when introduced into a healthy organism
4.) the microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent
what are some limitations to Koch's postulates?
-only 10% of bacteria are able to be cultured in lab
-at this point in history we still don't have an understanding of the asymptomatic carrier
-there are certain diseases that are human-specific
which is NOT a limit of Koch's postulates?
some bacteria are identical but cause different diseases
Ignaz Semmelweis (1818-1865)
Hungarian physician who pioneered antiseptic procedures
-"savior of mothers"
multiple hypothesis to explain different rates of peripheral fever:
-ringing of bell
colleague of Semmelweis cuts himself during autopsy:
-becomes ill with same disease
-ultimately dies from disease
Semmelweis concluded:
there must be cadaverous particles transmitted
Joseph Lister, 1st Baron Lister 1827-1910
British surgeon who pioneered antiseptic surgery through the use of phenol
Florence Nightingale (1820-1910)
-nurse who introduced antiseptic techniques
-decreased mortality rates of soldiers during Crimean War
John Snow
father of modern day epidemiology
epidemiology
the study of the distribution and determination of health-related states or events in specified populations, and the application of this study to the control of health problems
Gram's stain
-the most widely used staining technique
-one of the first steps to identify a bacterium
Enrlich's "Magic Bullets"
-if stains could color microbes differently, chemicals could kill microbes differently
-Arsenic based drug that treated syphilis (serious side effects, chemotherapy)
Edward Jenner (1749-1823)
-pioneered the smallpox vaccine
-vaccination was common but extremely risky
-proved protection from smallpox through vaccination
Jonas Salk (1955)
-American physician who developed polio vaccine
-used an inactivated strain of polio
processes of life:
growth, reproduction, responsiveness, metabolism
prokaryotes
lack nucleus, can transcribe DNA and make protein simultaneously
-lack various internal membranes
-are typically 1.0 micrometer in diameter or smaller
-composed of bacteria and archaea
eukaryotes
have nucleus, have internal membrane-bound organelles, are larger: 10-100 micrometers in diameter, have more complex structure, composed of algae, protozoa, fungi, animals, and plants
bacterial cell walls
protection, structure, attachment
-composed of peptidoglycan
-2 basic types of bacterial cell walls (Gram + and Gram -) ---> both have a lipid membrane
peptidoglycan layer much ________ in Gran (+)
thicker
Gram (-) have:
inner and outer membrane
periplasmic space
in Gram (-), the space between the inner membrane and outer membrane
2 different modified version of glucose used in peptidoglycan:
N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
which medium has a cross-bridge?
Gram (+) ONLY
which organelles exist in bacteria?
NONE
which type of bacteria have an inner and outer membrane?
Gram (-)
prokaryotes can undergo ________ and _______ of a gene simultaneously
transcription and translation
LPS
-used to classify bacteria
-Lipid A is an endotoxin
-O-Antigen can have 50-100 repeating subunits of polysaccharides
how many polysaccharides per unit?
4-7
Gram stain steps
1.) crystal violet
2.) Grams iodine
3.) Acetone/Ethanol wash
4.) safranin
coccus
circular
coccobacillus
oval rod
vibrio
comma shaped
spirillium
wave-like
spirochete
spiral
glycocalyces
Gelatinous, sticky substance surrounding the outside of the cell
-composed of polysaccharides, polypeptides, or both
2 types of glycocalyces:
capsule and slime layer
capsule
firmly attached to cell surface, may prevent bacteria from being recognized by host
slime layer
loosely attached to cell surface, water soluble, sticky layer allows prokaryotes to attach to surfaces
flagella
responsible for movement, are not present on all bacteria
flagella structure
composed of filament, hook, and basal body
basal body
anchors the filament and hook to cell wall
monotrichous
one flagellum at one polar end of the cell
Amphitrichous
a flagella at either end of the poles
lophotrichous
"tuft" at one pole
peritrichous
flagella all over the cell
fimbriae
sticky, bristle-like projections
-used by bacteria to adhere to one another and to substances in environments (biofilms)
-shorter than flagella
pili
special type of fimbriae
-conjugation pili --> genetic exchange
-longer than fimbriae but shorter than flagella
-bacteria typically have only one or 2 per cell
which type of bacteria have endotoxins?
Gram (-)
which extracellular structure is the shortest (on average)?
fimbriae
you have a sample of Gram (+) and Gram (-) cells. When performing the Gram stain you forget the acetone/ethanol rinse. What color do the Gram (-) cells appear?
purple
function of bacterial cytoplasmic membrane
-Energy storage
-Harvest light energy in photosynthetic bacteria
-Selectively permeable
-Naturally impermeable to most substances
-Proteins allow substances to cross membrane
-Maintain concentration and electrical gradient
structure of bacterial cytoplasmic membrane
referred to as phospholipid bilayer --> composed of lipids and associated proteins
phospholipids have a:
polar head and nonpolar unsaturated fatty acid tails
passive processes
diffusion, facilitated diffusion, osmosis
prokaryotic cytoplasmic membrane function
active processes: active transport, group translocation
group translocation
substance is chemically modified during transport
mechanisms of active transport
- uniport
- antiport
- coupled transport: uniport and symport
coupled transport
using the energy by allowing a H-ion to flow inside of the cell
cytoplasm of bacteria contains:
cytosol, inclusions, and endospores
cytosol
liquid portion of cytoplasm, mostly water, contains cell's DNA in region called the nuceloid
inclusions
may include reserve deposits of chemicals
endospores
unique structures produced by some bacteria, defensive strategy against unfavorable conditions
-resistant to extreme conditions such as heat, radiation, chemicals
-most are Gram (+)
vegetative cells transform into endospores when:
multiple nutrients are limited
eukaryotic cell walls and cytoplasmic membranes:
-all eukaryotic cells have these
-are a fluid mosaic of phospholipids and proteins (protein rafts)
-contain steroid lipids (fluidity)
-control movement into and out of cell
ribosomes
larger than prokaryotic ribosomes (80S vs. 70S), composed of 60S and 40S subunits
prokaryote is:
50S and 30S
Cytoskeleton
extensive network of fibers and tubules, anchors organelles, produces basic shape of cell
nonmembranous organelles
ribosomes and cytoskeleton
Mitochondria
have 2 membranes composed of phospholipid bilayer, produce most of cell's ATP, interior matrix contains 70S ribosomes and a circular molecule of DNA
endosymbiotic theory
-eukaryotes formed from union of small aerobic prokaryotes with larger anaerobic prokaryotes
smaller prokaryotes:
-lost ability to exist independently
-dependent on for aerobic ATP production
-aerobic prokaryotes evolved into mitochondria
-similar origin of chloroplasts
evidence of endosymbiotic theory
-divide by binary fission
-both have their own genome
-more closely resembles prokaryote genome
-ribosomes more closely resemble prokaryote
prokaryote genome
single circular DNA, no histones
The microbes commonly known as ________ are single-celled eukaryotes that are generally motile.
protozoa
which scientist reduced the rate of puerperal fever by advocating for the practice of hand washing?
Semmelweis
Whose search for chemicals that would kill microbes without harming humans was the foundation for chemotherapy?
Ehrilch
which is NOT evidence that supports the endosymbiont theory?
mitochondria have linear DNA
mitochondria divide by:
binary fission
mitochondria have:
ribosomes that are more similar to prokaryotes
mitochondria have their own:
DNA
general principles of microscopy
-wavelength of radiation
-magnification
-resolution ---> wavelength, numerical aperture
-contrast
numerical aperture
the amount of light that is capable of being collected and focused up into the human eye as you're looking through the microscope
contrast
differences in intensity between 2 objects, or an object and its background
-important in determining resolution
-staining increases this
staining
-most microorganisms are difficult to view by bright-field microscopy
-coloring specimen with stain increases contrast and resolution
-specimens must be prepared for this
principles of staining
-dyes used as stains are usually salts
-chromophore is the colored portion of the dye
-acidic dyes; basic dyes; simple stains
-used to determine size, shape, and arrangement of cells
simple stains
composed of a single basic dye
differential stains
-use more than one dye
-distinguishes between different cells, chemicals or structures
common differential stains include:
Gram stain
Acid-fast stain
Endospore stain
Histological stains
2 common stains used for histological specimens
-Gomon methenamine silver (GMS) stain
-Hematoxylin and eosin (HE) stain
special stains
Simple stains used to identify specific microbial structures
special stains include:
Negative stains
Flagellar stains
Fluorescent stains
Staining for Electron Microscopy
Chemicals containing heavy metals used for transmission electron microscopy
-stains may bind molecules in specimens or the background
light microscopy
bright-field microscopes
-simple contain a single magnifying lens
-Leeukwenhoek used simple microscope to observe microorganisms
compound microscope
-series of lenses for magnification
-light passes through specimen into objective lens
-have 1 or 2 ocular lenses
-total magnification = magnification of objective lens x magnification of ocular lens
-most have condenser lens (direct light through specimen)
-oil immersion lens increases resolution
dark-field microscopes
-best for observing pale objects
-only light rays scattered by specimen enter objective lens
-specimen appears light against dark background
-increases contrast and enables observation and more details
fluorescence microscopes
-direct UV light source at specimen
-specimen radiates energy back as a longer, visible wavelength
-UV light increases resolution and contrast
-some cells are naturally fluorescent; others must be stained
-used in immunofluorescence to identify pathogens and to make visible a variety of proteins
confocal microscopes
-use of fluorescent dyes
-use UV layers to illuminate fluorescent chemicals in a single plane
-resolution increased because emitted light passes through pinhole aperture
-computer constructs 3D image from digitized images
electron microscopy
-light microscopes cannot resolve structures closer than 200 nm
-electron microscopes have greater resolving power and magnification
-magnifies objects 10,000 x to 100,000 x
-detailed views of bacteria, viruses, internal cellular structures, molecules, and large atoms
2 types of electron microscopes
transmission electron microscope and scanning electron microscope
TEM
-visualizes electrons that are transmitted through the specimen
-allows for visualization the inside of cells
SEM
-visualized electrons that are scattered off the specimen
-allows to visualize the 3D features of a specimen and surroundings
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