Chapter 7- Microbial Growth and Reproduction Flashcards
replicate genetic material, cytoplasm, and cytoplasmic structure, mitotic/meiotic, diploid/haploid
reproductive strategies
haploid asexual reproduction only, binary fission, budding, replication and segregation of genome prior to division
bacteria and archaea
cell gets roughly 2X in size, divides genetic material and cytoplasm equally between the 2 cells
binary fission
a piece of the cell, genetic material with little cytoplasm, pinches off to form a new cell and then grows bigger
budding
formation of new cell through next cell division, mostly through binary fission, cytokinesis and DNA replication/partition
bacterial cell cycle
site where replication begins
single origin of replication
site where replication is terminated
terminus
group of proteins needed for DNA synthesis
replisome
most are circular, proceeds in both directions from the origin, origins to opposite ends of the cell
chromosome replication
replisome pushes daughter chromosome to opposite ends, MreB determines cell shape and chromosome segregation, new origins associated with MreB tracts, no segregation if mutated
chromosome partitioning
ParM, ParC, and ParR are___________________
the 3 proteins essential for inheritance produced by E. coli
the formation of cross walls between daughter cells
septation
selection of site for septum formation, assembly of z ring, linkage of z ring to plasma membrane, constriction of cell and septum formation
enzyme dictation during septation
microbial growth usually refers to ____________ growth rather than growth of ____________ cells
population, individual
used for microbial growth, transport, and storage of microorganisms, can be solid or liquid, need all nutrients required for organism for growth, classified based on chemical composition, physical nature, and function
culture media
all components and their concentrations are known
defined or synthetic media
contain some ingredients of unknown composition or concentration
complex media
protein hydrolysates prepared by partial digestion of protein sources
peptones
can include aqueous, beef or yeast
extracts
sulfated polysaccharide used to solidify liquid media, most microorganisms cannot degrade it
agar
media containing minimal nutritional requirements for microorganism, varies btwn microbes
minimal media
media with more than minimal requirements, quicker growth, contains proteins, amino acids, starches, and lipids
rich media
support the growth of many microorganisms
general purpose media
general purpose media with addition of blood supplements
enriched media
favor a growth of specific microorganism, have an inhibiting agent, MacConkey agar
selective media
no inhibiting agent, allow things to grow differently
differential media
group of cells that derive from one original cell, clones
colony
population of cells arising from a single cell
pure culture
spread cells across surface, cells separated from each other, each cell can reproduce to form a separate colony
streak plate
small volume of diluted mixture, 30 to 300 cells transferred, spread evenly over surface with a sterile bent rod
spread plate
sample is serially diluted, mixed with liquid agar, poured into sterile culture dishes, both may be used to determine number of microorganisms in original sample
pour plate
observed in microorganisms cultivated in a batch culture, incubated in a closed vessel, cell number versus time, 3 or 4 distinct phases
growth curve
phase that doesn’t always occur, 0 to 30 minutes, interval of time when culture is inoculated and begin to grow, cell synthesizes new components and replenish spent materials
log phase
division>death, good space and nutrients, max rate of growth, similar to log phase, 4 to 8 hours
exponential phase
cell division = cell death, can last for days or weeks, growth of population is zero, nutrients are gone
stationary phase
can last forever, death>division
death phase
nutrient depletion, limited oxygen availability, toxic waste accumulation, critical population density reached
reason for stationary phase
entry of stationary phase is due to _________
starvation
increase cross linking in cell wall, Dps protein protects DNA, chaperone proteins prevent protein damage, cells are called persister cells (have long term survival and increased virulence)
production of starvation proteins
two theories of death sequence
(1) cells are viable but not culturable (cells alive and dormant, capable of new grown when conditions are right)
(2) programmed cell death (genetically programmed to die)
time required for a population to double in size, varies depending on species and environmental condition, ranges from 10 minutes to several days
generation (doubling) time
direct cell counts, counting chambers, membrane filters
direct measurement of cell numbers
easy, quick, and inexpensive, for both prokaryotes and eukaryotes, can’t distinguish living from the dead
counting chambers
cells filtered through special membrane with dark background, cells are stained with a fluorescent dye, useful for counting bacteria, certain dyes distinguish living from dead
direct cell count on membrane filters
microbial suspension with laser light beam through small orifice, movement of microbe through orifice, instance of disruption from current are counted, some antibodies used to determine size and complexity
flow cytometry
cell viability isn’t clear cut because of __________
the many states between dead and alive
after dilution of bacteria and incubation, number of organisms = colonies x dilution factor
viable counting method for pour/spread technique
growth in an open system, continual provision of nutrients, continual removal of wastes and cells, cells in log phase at constant biomass concentration, continuous culture system
continuous culture of microorganisms
device for continuous culture, rate of incoming medium = rate of removal of medium, essential nutrient in limiting quantities
chemostat
in a hypotonic solution, cells are ___________, water _________ the cell, and they may __________
hypertonic
enters
swell and burst
in a hypertonic solution, cells are ___________, water _________ the cell, and ___________.
hypotonic
leaves
plasmolysis
How do microbes reduce osmotic concentration of the cytoplasm in a hypotonic solution?
mechanosensitive (MS) channels in cell membrane allow solutes to leave the cell
How do microbes increase internal solute concentration in a hypertonic solution?
solutes are used and compatible with metabolism and growth
most cells try to stay __________ to their environment
slightly hypertonic
grow optimally in NaCl or other salts at 0.2M
halophiles
require salt concentrations of 2M to 6.2M, high concentration of potassium, cell wall, protein, and membranes require more salt for stability
extreme halophiles
relative acidity of a solution, measure concentration of H+ ions in a solution
pH
pH of 0 to 5.5, mostly prokaryotes, many Archaea
acidophiles
pH of 5.5 to 7, most microorganisms
neutrophiles
pH of 8.5 to 11.5, mostly prokaryotes, mostly prokaryotes
alkaliphiles or basophiles
Why do most cells strive for a pH of 7?
keep proteins and nucleic acids, plasma membrane is impermeable to protons, exchange potassium for protons, buffers
True of False: Microorganisms can change external pH through waste?
True
Microorganisms are __________ because they cannot regulate their internal temperature
ambitherms
grow at 0 to 20 C
psychrophiles
grown at 0 to 35 C
psychrotrophs
grow at 20 to 45 C
mesophiles
grow at 55 to 85 C
thermophiles
grow at 85 to 113 C
hyperthermophiles
grow optimally at a low temperature, extreme representatives that inhabit permanently in cold environments
psychrophile
grow optimally at a mid range temperature, warm blooded animals, terrestrial and aquatic environments, temperate and tropical latitudes
mesophile
grow optimally at a high temperature
thermophile
grow optimally at a very high temperature
hyperthermophile
production of enzymes and transport proteins that function optimally in cold, more a helices than B sheets, more polar and less hydrophobic amino acids, fewer weak bonds, high unsaturated fatty acid content, fewer hopanoids
psychophile adaptations
more H and disulfide bonds, histone like proteins stabilize DNA, more saturated and dense lipids in cell membrane, ether linkages
thermophile adaptations
growth in oxygen correlates with a microbes energy conserving metabolic processes wand the electron transport chain
oxygen concentration
all organisms that use aerobic cellular respiration as its only energy yielding metabolism require ___ as a final electron acceptor
O2
usually live in 20/21% O2, die in its absence, perform only aerobic cellular respiration
strict aerobes
live in 2-10% O2 concentrations
microaerophiles
organisms that use some other method of energy metabolism and have no O2 requirement
anaerobes
organisms that can tolerate O2 and grow in its presence even though they cant use it
aerotolerant anaerobes
organisms that dies in the presence of any O2, found in deep water and deep soil
strict anaerobes
live in presence or absence of oxygen, aerobic cellular respiration when present, some other form when absent, nearly all prokaryotes and fungi
facultative anaerobes/aerobes
damage proteins and nucleic acids, can mutate and cell death can occur when above the threshold of protection, include single oxygen, superoxide anion, hydrogen peroxide, and hydroxyl radicle
toxic forms of oxygen
enzymes neutralize toxic species, aerobes and facultative aerobes have the most detoxyfing enzymes, microaerophiles and aerotolerant have none, strict have none
dealing with toxic forms of oxygen
H2O2 + H2O2 —–> 2 H2O + O2
catalase
H2O2 + NADH + H —> 2 H2O + NAD+
peroxidase
O2- + O2- + 2H —–> H2O2 + O2
superoxide dismutase
What are 3 enzymes that destroy toxic oxygen species?
(1) catalase
(2) peroxidase
(3 superoxide dismutase
strict anaerobic microorganisms lack or have a low quantity of __________ and ___________ due to their ability to tolerate oxygen
superoxide dismutase and catalase
adversely affected by increased pressure, not as severely as non-tolerant organisms
barotolerant
require or grow more rapidly in the presence of increased pressure, change membrane fatty acids to adapt to high pressures
barophilic
include x-rays and gamma rays, mutations occur in low doses and cell death occurs in high doses, disrupts chemical structure, damage may be repaired by DNA repair mechanisms for small dose of damage
ionizing radiation
wavelength most effectively absorbed by DNA, can cause mutations but more death, causes formation of thymine dimers in DNA
ultraviolet (UV) radiation
high intensities generate single oxygen, serve as powerful oxidizing agent, carotenoid pigments for protection
invisible light
complex and constantly changing, low nutrient concentrations, may expose a microorganism to overlapping gradients of nutrients and environmental factors
microbial growth in natural environments
microbes reversibly attach to conditioned surface, release polysaccharides, proteins, and DNA to form extracellular polymeric substance
formation of biofilm
maturity leads to increased complexity and involvement in a community of microorganisms, form on a surface that is conditioned, interactions occur along the attached organisms, formation on medical devices leads to illness
biofilms
microbes produce small proteins that increase in concentration as microbes replicate and convert themselves to a competent state
cell to cell communication within microbial populations
