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165 Cards in this Set

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Microbiology
biology of small orgamisms (<1mm) too small to be seen with unaided eye-- but not all are microscopic
Microbiology
methods of study - use of microbiological methods (isolation and culture or an organism from a mixed population)
meat and maggot experiment
disproved theory of spontaneous generation until microscope
Anton van Leeuwenhoek
- 1st to observe microbes under microscope.
- revived theory of spontaneous generation
Louis Pasteur
- refutes theory of spontaneous generation with experiments
Louis Pasteur
- use of SWAN NECK flasks to keep growth media sterile
Louis Pasteur
- developed STERILE TECHNIQUE of tissue culture
role of microbes in disease
evidence in mid 1800s- effect of fungi in causing silkworm disease and potato blight
Joseph Lister
INDIRECT evidence for microbes as causative agents of human disease
Joseph Lister
antiseptic agents that kill microbes also prevent surgical infections; birth of antiseptic surgery
Robert Koch
DIRECT evidence that microbes cause disease through study of anthrax.
Robert Koch
developed GERM THEORY of disease
Robert Koch
mouse experiments
1. microbe must be present in all cases of disease and absent from healthy orgs.
2. putative pathogen must be isolated and grown in pure culture
3. isolated org. must cause same disease in a healthy host
4. same organism must be isolated again from newly diseased host
Koch's Postulates
1. cut and boiled potatoes: unreliable
2. addition of gelatin to liquid broth: better but gelatin melts at 30degrees and digested by some bacteria
3. use of agar: very successful- add nutrient broth to agar
4. development of petri dish
culture of bacteria on solid media
Pasteur
demonstrated that fermentations were the result of microbial activity
Carbs, lipics, nucleic acids, proteins
Biological macromolecules
70% H2O; 30% chemicals
cell composition
20
number of elements found in biological macromolecules (living orgs.)
CHOPSN
6 elements found in high amounts in living orgs.
covalent bonds
- strong bonds
- formed and broken by enzymes
Hydrogen bonds
- weak bonds- form and break spontaneously
- between H and more electroneg. element (N,O)
Carbohydrates (sugars)
- act as energy source
- constituent of cell wall
- component of nucleic acids
carbs
glycosidic bonds
lipids
insoluble in H2O; soluble in non-polar organic solvents
lipids
- important energy source
- constituent of cell membranes
lipids
simple fat- glycerol and fatty acids

complex- simple and additional cmpd

sterols- cholesterol-like fats
Nucleic Acids
made of nucleotide monomers
nucleic acids
polymers= DNA and RNA
Proteins
amino acid monomers
proteins
connected by peptide bonds
proteins
most known enzymes (some are RNAs)
proteins
form important structural components of cells
- eukaryotic cytoskeleton
- muscles- actin
primary structure
linear order of amino acids
secondary structure
shape along single axis in space
- alpha helix, beta sheet
tertiary structure
3-D organization of the individual secondary structures
quarternary structure
occurs when a protein has more than one subunit. shows how subunits associate with each other
primary, secondary, tertiary
all proteins have what structures? (TQ!)
secondary, tertiary, quarternary
what protein structures are stabilized by non-covalent bonds (H and disulfide)?
primary
what protein structure is stabilized by covalent bonds?
produce an enlarged image of an object
what is the function of a microscope
simple microscope
single lense (magnifying glass)
comound microscope
more than one lense (most microscopes today)
- prisms bend light
- lenses act like collections of prisms
- magnifying power= strength
principles of lenses
high mag.
small focal length (fat lense) = high or low mag?
low mag
long focal length (thin lense)= high or low mag
light microscope
use of light to produce an image
electron microscope
use of electrons to produce image
1. light source
2. stage
3. condenser
4. objective lenses
5. eyepiece lense (ocular)
1. provides illumination
2. platform for holding slides
3. focus light on slides
4. REAL primary image (TQ!)
5. magnifies primary image- VIRTUAL secondary image
objective mag X eyepiece mag
Total magnification calculation (TQ!)
resolution
ability to distinguish 2 very close objects as distinct entities.
resolution
measured as the min. distance (d) to distinguish between 2 objects that reveal them as separate entities. the smaller the value of d the better (d= .5wavelength/NA)
bright field microscope
produces a dark image on a bright background. mainly used to observe fixed and stained (dead) cells
dark field microscope
used to observe living and unstained cells. produces bright image on dark background
phase- contrast microscope
used to observe living and unstained cells. enhances contrast btwn intracellular structures having slight differences in refractive index (bright around edges)
electron microscope
microscope that uses electromagnets instead of glass lenses and electrons instead of light
transmission EM
reveals great detail of internal structure of cells (2-D image). slice sample into thin layers- can reconstruct 3-D image
scanning EM
reveals great detail of external structure of cells (3-D image)
Fixation of a specimen
required for preservation of cell structure and also attaching specimen to slide
heat- quick and convenient; not good for preserving cell structure
chemical- time consuming; good for preserving cell structure and shape
2 ways to "fixate" a specimen
staining of a specimen
required for "seeing" certain cellular structures through use of dyes
1. simple staining
2. differential staining
What kind of staining
1. use of a single dye
2. use of >1 dye
prokaryotes
bacteria, archae
no nuclear membrane
eukaryotes
algae, fungi/yeast, protozoa
possess nuclear membranes
cocci
Shapes of bacterial cells
spheres
gram + (exception= Neisseria)
bacilli
Shapes of bacterial cells
rods
gram - (exception bacilli)
1. no membrane bound organelles
2. cell wall- external to plasma or cell membrane
prokaryotic cell structure
plasma membrane
what prokaryotic cell structure?
- encloses cytoplasm, selectively permeable, comprised of proteins and lipids, lack cholesterol but have cholesterol-like HOPANOIDS which control fluidity of membrane
protoplast
plasma membrane + cytoplasm
integral protein
protein embedded in membrane and also amphipathic. Not static but can diffuse in plane of memrane
peripheral protein
protein with loose association with membrane
cytoplasm
what prokaryotic cell structure?
- mostly water (75%), harbors nucleoid, ribosomes, inclusion bodies
ribosomes
one of the main components of translation machinery
- 2 subunits made of proteins and rRNA
large= 50 s
small= 30s
total = 70s
prokaryotic ribosome size
inclusion bodies
what prokaryotic cell structure?
- act as storage granules for nutrients- contains organic or inorganic material
Nucleoid
contains the genetic material (DNA), RNA, and proteins (necessary for compaction)
nucleoid
almost always a single circular chromosome, chromosome associated with the plasma membrane (attached at the mesosome)
Gram +
Cell wall and PG (thick)
(Gram + or -)
Gram -
has membrane which makes it hard to treat with drugs
plasma membrane and PG (thin) and outer membrane
(Gram + or -)
cell wall
consists of all structures external to plasma membrane
(gram +)
NAG and NAM
alternating D and L aa's connected to NAM
Peptidoglycan subunits= 2 linked glucose derivatives
gram +
aa # 3= L-Lysine
(Gram + or -)
gram -
aa # 3= DAP
(Gram + or -)
shape and protection from osmotic lysis
Role of PG
osmotic lysis
lots of salt inside cell- water flows in to make conce= in and out
cell expands and bursts b/c membrane not strong enough
btwn aa #3 and 4
linkage of PG subunits
Gram + cell
- thick PG
- large quantities of TA
Gram - cell
- more complex
- thin PG
- includes outer membrane containing LPS or endotoxin
- more permeable than plasma membrane
capsule
prokaryotic structure
- outside cell wall
- not seen in all bacteria
- helps resist phagocytosis by white blood cels
- enhances adherence to host tissues
Pili or Fimbriae (same)
- sex pili larger than regular
- short, hair-like structures on cell surface
- role in attachment to host tissues
- important for twitching and gliding motility of some bacteria
flagella
used for motility for most bacteria
bacterial endospores
dormant structures formed as protection in response to adverse environmental conditions. only formed by a few bacteria
- contain large amts of DPA
eukaryotic cells
characterized by presence of membrane bound organelles which provide environment for distinct metabolic rxns.
cytoplasmic matrix (inside plasma membrane)
Eukaryotic structure
- mostly water (75%)
- harbors organelles and cytoskeleton
cytoskeleton
(prokaryotes have their own version)
important for cell shape and motion
- filamentous components
ER
eukaryote structure
- network of tubules and flat sacs involved in protein and lipid transport
rough ER
involved in intracellular transport and "modification" of secreted proteins
smooth ER
involved in lipid metabolism and detox of chemicals
Golgi
series of flattened sacs in close association with the ER
Golgi
receives material from ER and acts as a packaging and sorting organelle for transport of lipids
lysosomes
synthesized by ER/Golgi system
lysosomes
required for intracellular digestion of macromolecules and destruction of ingested microbes
lysosomes
contain a class of enzymes called HYDROLASES that function at a low pH (hydrolyze macromolecules)
ER, Golgi, lysosomes, endosomes (vaculoes formed when plasma memrane engulfs extracellular material)
cellular import/export system.. in order
eukar ribosomes
organelles of protein synthesis
nucleus
membrane bound organelle containing linear chromosomes
large= 60s
small= 40s
total= 80s
eukar ribosome subunits sizes
nucleus
eukar structure
chromosomes packaged into CHROMATIN by proteins known as HISTONES
nucleus
eukar structure
-contains a prominent NUCLEOLUS, site of rRNA synthesis and assembly of ribosomal sub-units
nucleolus
site of rRNA synthesis and assembly of ribosomal sub-units
cristae
site of respiration
thylakoid membrane (chloroplast)
site of photosynthesis
mitochondrial matrix
eukar. structure
- contains DNA and bateria-like (70s) ribosomes
nutrient
compound required for biosynthesis and energy
CHOPNS
major elements
- required in g/L amounts
K, Ca, Mg, Fe, Na
minor elements
- required in mg/L amounts
minor elements
required as enzyme co-factors or for activity of certain enzymes
C, P, Na
macroelements
Mn, Zn, Co, Ni, Mo, Cu
Microelements (trace elements)
- required as enzyme co-factors or for activity of certain enzymes
- microgram/L amts
carbon energy electrons
Microbial classification based on sources of nutrient and energy acquisition
carbon
backbone of all organic molecules
autotrophs
use CO2 as sole or main source of carbon
heterotrophs
use organic molecules pre-formed by other organism
phototrophs
light as energy source
chemotrophs
oxidation of organic and inorganic compounds as energy source
lithotrophs
"rock eaters" reduced inorganic molecules as electron source
organotrophs
use organic cmpds as a source of electrons
-synthesis of important molecules
N, P, S required for:
- organic cmpds
- essential cell components (or their precursors) that the cell cannot synthesize
- must be supplied by environment if cell is to survive and reproduce
growth factors
- selective
- accumulation against concentration gradient (for most)
- movement across barrier- plasma membrane
- Gram - has to cross outermembrane too, so crosses 2 membranes
nutrient uptake
passive diffusion
very inefficient and not an important means of nutrient uptake
facilitated diffusion
- faster than passive b/c concentration gradient is still necessary
to increase the rate of diffusion, cells utilize carrier proteins known as PERMEASES (plasma membrane proteins) to transport cmpds.
chemical modification (phosphorylation) of transported compound
- requires energy input
- found in prokaryotes
group translocation
active transport
requires the expenditure of chemical energy to move molecules "uphill" against a gradient.
permease, energy, substrate change
1. none
2. permease
3. permease, energy
4. permease, energy, substrate change
Nutrient Transport Mechanism
1. passive
2. facilitated
3. active
4. group translocation
endocytosis
- take nutrients in
- found in eukar
- solutes or particles enclosed in vesicles pinched off from plasma membrane
- vesicles fuse w/ lysosome to digest material and release nutrients- break down into smaller usable parts
- samples are collected from cold environments
- psychrophilic (cold-loving) bacteria are isolated and cultured
isolation of bacteria from environ.
psychrophilic
cold-loving bacteria
known chemical composition
defined/synthetic culture medium
unknown chem. composition, but "rich"
complex culture medium
permits growth of only certain microbes in a mixed pop. (growth vs. no growth)
selective culture medium
distinguishes btwn different subsets of microbes (lactose fermenting and non-fermenting microbes)- different appearance
differential culture medium
no add. of nutrients or removal of waste products. over time nutrients inc. and waste dec.
closed system
(first) lag phase
no increase (flat), synthesis of new cellular components
(second) exponential phase
maximal growth rate, constant growth rate (cell # doubles atregular time intervals), phase when cell pop is most chemically and physiologically uniform
(third) stationary phase
# viable orgs remains constant
- death rate= growth rate so no net inc. or dec.
(fourth) death phase
decrease in viable count, log decreae
measured during exponential phase, time for a 2-fold increase in cell # (TQ!)
doubling or generation time
# generations/unit time

ex. generations per hour
growth rate constant
direct counting
count # cells in a chamber of known volume (petroff-hauser chamber)
- adv= quick and simple
- disadv= NOT viable cell count
electronic counting
- NOT a viable count
microbial suspension forced through small orifice
- movement of microbe through orifice impacts electric current that flows through (coulter counter)
- instances of disruption of current are counted
viable counts: spread plate, pour plate
perform serial dilutions of sample and determine # cells
# colonies forming units per ml.
(# colonies/vol. plated)
# viable cells
more cells= more scattered light= OD
- OD= amount of light that DOESNT get through
- high OD= more cells
- NOT viable count
optical density
growth in constant environment
- steady provision of nutrients and waste removal
- growth maintained at exponential rate
open system- chemostat
for most cells, higher the salt (osmolarity), the more difficult it is to grow: due to PLASMOLYSIS- removal of water from cell
osmolarity
prefer growth in high salt environments
HALOPHILES
model for life on mars
- can survive in salt deposits after water evaporates
extreme halophiles
min, optimum, max
- prokar. can grow at much higher temps than eukar.
Cardinal temps
low optimum temp
PSYCHROPHILES
20- 40 degrees optimum (most humans)
MESOPHILES
high optimum (>55)
THERMOPHILES
preferred growth environ. can be classified as:
- acidophile
- neutrophiles
- alkalophiles
pH
- cytoplasmic pH of most orgs is close to neutral
oxygen
final electron acceptor for aerobic respiration
1. need oxygen
2. prefer oxygen
3. ignore O2 (doesnt matter)
4. oxygen is toxic
5. < 2-10% oxygen (low level)
1. obligate aerobe
2. facultative anaerobe
3. aerotolerant anaerobe
4. strict anaerobe
5. microaerophile