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characteristics of prokaryotes
no nucleus, very small, bacteria and archea, peptidoglycan
similarities in prok. and euk. cells
cytoplasm, ribosomes, and cell membrane present
use chemical reactions
things prokaryotes do due to their size
reproducing quickly, adapting easily to their environment, simple organization
capsule/glycocalyx
protects against phagocytosis
outside cell wall, not always present
made of polysaccharides
2 types: capsule and slime layer
capsule is firmly attached and protects from phagocytosis, slime layer is loosely attached and protects from water loss
cell wall
protects and gives cell shape
cell membrane
site of ATP production, selective barrier, phospholipid bilayer
ribosome
protein synthesis, 2 subunits
very numerous in cells that are actively growing
flagella
cell movement
fimbriae
attachment, protection, biofilms
cytoplasm
fluid inside cell, 80% water, where most chemical reactions happen
nucleoid
cluster of genetic material
coccus
spherical shape
ex: Staphlococcus epidermis
bacillus
rod shaped
ex: Bacillus anthracis
vibrio
spiral shaped
ex: Vibrio cholerae
pleomorphic
many shapes
ex: Helicobactor pylori
strepto
cells in chains
ex: Streptococcus aureus
staphlo
cells in grape-like clusters
ex: Staphlococcus aureus
diplo
cells in pairs
ex: Enterococcus faecalis
monotrichous
one flagellum at one end of a cell
amphitrichous
one flagellum at both ends of a cell
lophotrichous
tuft of flagellum at one end of a cell
peritrichous
flagellum around the entire surface of a cell
run
flagella moving in one direction
tumble
flagella stopping and changing direction
taxis
movement toward or away from a stimulus
pili
longer than fimbriae, 1 to 2 per cell
used in conjugation
basic structure of cell wall
peptidoglycan is the main component
2 monosaccharides: NAG and NAM
amino acids form crossbridges
gram positive cell wall structure
25-30 layers of peptidoglycan
teichoic acids present
gram negative cell wall structure
5-10 layers of peptidoglycan
no teichoic acids present
has LPS (lipopolysaccharide) outside peptidoglycan
LPS layer is toxic to humans, responsible for symptoms, and often resistant to antibiotics
simple diffusion
movement of molecules from high to low
osmosis
diffusion of water across membrane
isotonic solution
cell stays the same
equal concentration
hypotonic solution
lower concentration of solutes outside cell
H2O moves into cell
lysis
hypertonic solution
higher concentration of solutes outside cell
H2O moves out
plasmolysis (crenation)
solute
substance dissolved
solvent
medium in which substances are dissolved
inclusions
large storage molecules in the cell made of C, N, and P
endospores
formed when nutrients are limited
contains thick cell walls
can live for 25 million years
killed by autoclave
bacillus and clostridium have them
biofilms
communities of microbes
thin, slimy layers that encase bacteria and adheres them
more resistance to antibiotics
ex: on rocks, teeth, ect.
element
simplest form of matter
atoms
smallest particle of element
protons, neutrons, electrons
molecule
2 or more chemically joined atoms
ex: O2
compound
molecule composed of 2 or more different elements
ex: CO2
ionic bond
attraction between 2 oppositely charged ions
anion
ion wth a negative charge
cation
ion with a positive charge
carbohydrates
contain C, H, and O
monosaccharides
H:O is 2:1 ratio
names often end in -ose
lipids
contain C, H, and O
fats, oils, cholesterol, ect
proteins
contain C, H, O, and N
valine, alanine, tryptophan
nucleic acids
contain C, H, O, N, and P
microbial growth
increase in number of cells
occurs by binary fission
colony
group of cells that can be seen without a microscope
colony forming units (CFUs)
estimates the number of bacteria that are living
culture
microbe growing on media
inoculum
microbe added to media
inoculate
process of adding microbes to media
incubate
time and temp. for inoculated media
five I’s for growing microbes
inoculation, incubation, isolation, inspection, and identification
complex media
type of media that uses substances where precise contents are unknown
ex: yeast, casein, peptone, beef extract
chemically defined media
media where exact chemical composition is known
ex: magnesium sulfate (MgSO4 7H2O)
selective media
type of media that only allows specific types of microbes to grow
ex: sabouraud agar allows microbes to grow at low pH
differential media
type of media that only allows different microbes growing on the same media to be distinguished
enrichment culture
a set of condition for a microbe
pure culture
only one type of microbe
(robert koch)
mixed culture
more than one type of microbe
quadrant streak plate method
four zones of growth are created to isolate pure colonies
zone 1 has the most colonies and zone 4 has the least
zone 4 has the most isolated colonies
obligate anaerobes
die in presence of oxygen
ex: Clostridium tetani
facultative anaerobes
use oxygen if present, but can grow without it
ex: E. coli
aerobes
require oxygen
anaerobes
do not require oxygen
aerotolerant anaerobes
can survive in the presence of oxygen, but don’t use it
ex: Lactobacillus
cardinal temperature
minimum, optimum, and maximum temperatures for bacteria
minimum temperature
lowest temperature at which growth will occur
optimum temperature
temperature at which growth is most rapid
maximum temperature
highest temperature at which growth will occur
psychrophile
“cold loving”
optimum below 15 degrees celcius
ex: Polaromonas vacuolata
psychrotroph
“cold tolerant”
optimum from 15 to 25 degrees celcius
ex: Staphlococcus aureus (food spoiler)
mesophile
“moderate temp. loving”
most common
ex: E. coli
thermophile
“heat loving”
optimum is 50-60 degrees celcius
acidophile
optimum pH below 6.5
found in areas with hydrochloric acid or sulfuric acid
alkaphile
optimum pH above 6.5
found in soda lakes
halophile
bacteria that require high salt concentration (13-25%)
plate count
way to measure microbial growth that is most common
measures number of viable cells
serial dilution
pour plate method
type of plate count method
bacteria added to liquid agar, mixture then poured into empty plates, agar solidifies, plate incubated
result: colonies grow within and on surface of agar
plates with 30-300 colonies are used to calculate original cell concentration (OCC)
spread plate method
type of plate count method
bacteria added to solid agar, spread over surface with sterile rod
result: only growth of surface of agar
direct microscopic count
way to measure microbial growth by looking through microscope and counting the number of bacteria
pros: no incubation time and cheap
cons: dead cells are counted
turbidity
way to measure microbial growth
the more bacteria, the more cloudy
uses spectrophotometer
beam of light passes through test tube
more bacteria = less lighyt
most probable number (MPN)
method of measuring microbial growth that is used when plate counts aren’t reliable
uses a table to estimate number of microbes in original sample using a serial dilution
often used to test water purity
binary fission
method in which most bacteria grows
generation
1 cell divides into 2
generation time
time it takes to complete generation
growth curve
graph that plots growth of a population
used to calculate generation time
uses logarithmic scale
lag phase
period of adjustment, slow growth
log or exponential phase
population is doubling
slope of line can be used to calculate generation time
phase when antibiotics most effectively kill bacteria
stationary phase
equal number of cells dividing and dying
cells are dying due to depletion of nutrients and accumulation of waste products
death phase
phase in which cells are dying
flash-freezing
method for preserving bacterial cultures
pure cultures of bacteria are quickly frozen and at -50 to -95 degrees celcius
lyophilization
method for preserving bacterial cultures
flash frozen
vacuum used to remove water
result is powder residue that can be revived by adding liquid media
