Chapter 7 - Microbial Growth & Reproduction Flashcards
eukaryotic microbes may reproduce blank or blank
sexual (meiosis), asexual (mitosis)
microorganisms must replicate blank and cytoplasm and cytoplasmic structures
genetic material
for both prokaryotes and eukaryotes, there are two common ways that cells blank
divide
cell gets roughly twice its size and then divides the genetic material and cytoplasm equally between two cells in this division
binary fission
a piece of the cell breaks off to form a new cell then grows bigger
budding
sequence of events from formation of a new cell through the next cell division
cell cycle
Ftsz protein is involved in this kind of cell division to form blank
binary fission, septum
most bacteria divide by blank
binary fission
most bacterial chromosomes are what shape
circular
site at which replication is terminated, located opposite the origin
terminus
group of proteins needed for DNA synthesis
replisome
actin homolog, plays role in determination of cell shape as spiral inside cell periphery, and chromosome segregation
MreB
plasmids carry proteins that are necessary for blank
segregation
formation of cross walls between daughter cells
septation
increase in cellular constituents that may result in increase in size, increase in number
microbial growth
growth usually refers to blank rather than growth of blank
population, individual cells
this can be solid or liquid prepped and needs to grow, transport, and store microorganisms in the lab
culture media
culture media must contain all blank for for microbe to grow
nutrients
contain some ingredients of unknown composition and or concentration type of media
complex media
protein hydrolysates prepared by partial digestion of various protein sources
peptones
media containing minimal nutritional requirements for a particular microbe; varies from microbe to microbe
minimal medium
medium containing much more than minimal; may have proteins, amino acids, starches, monosaccharides, ion, lipids
rich medium
complex media will probably have one of these
peptone, tryptone, extracts
microbes go faster in blank media
rich
support the growth of many microbes (rich media)
supportive/general purpose media
general purpose media supplemented by blood or other special nutrients
enriched media
bacteria like the blank in blood
iron
favor the growth of some microbes and inhibit others example is blank
selective media, macConkey agar
MacConkey agar selects for blank bacteria
gram negative
blank media allows different microbes to grow differently but doesn’t inhibit
differential
population of cells arising from a single cell developed by robert koch
pure culture
agar technique that involves spreading out the microbes with the loop to get single colonies
streak plate
small volume of liquid and glass rod then spread it over the plate to find single colonies
spread plate
sample is serially diluted and diluted samples are mixed with liquid agar then are poured into sterile dish
pour plate
culture plates can be used to determine the number of blank microbes in an original sample
viable
bacteria in a culture in a blank medium creates a growth blank
close, curve
growth phase that does not always occur and is the interval between when a culture is inoculated and when growth begins
lag phase
log phase of growth where cells are growing and dividing; maximum growth rate
exponential phase
growth curve phase where rate of population is zero because cell divisions = cell deaths
stationary phase
cell deaths are greater than cell divisions and there is not enough nutrients in medium to feed colony
death phase
cells alive, but dormant, capable of new growth when conditions are right
Viable But Not Culturable
fraction of the population genetically programmed to die and commit suicide
programmed cell death
time required for the population to double in size
generation time
generation time varies depending on species of blank and blank conditions
microbes, environmental
population is doubling every generation is blank population growth
exponential
generation time equation
g = t/n
t is the duration of blank growth
exponential
n is the number of blank
generations
g is the blank
generation time
these are useful for counting both eukaryotes and prokaryotes
counting chambers
counting chambers can not distinguish blank from blank cells
living, dead
microbial suspension forced through small orifice with a laser light beam
flow cytometry
flow cytometers are blank counters
electric
these allow enumeration of viable cells with blank and blank plate techniques
viable counting methods, spread, pour
CFU stands for blank
colony forming unity
each CFU comes from blank viable cell(s)
one
bacteria from aquatic samples are trapped on membranes and membrane is soaked in culture media
membrane filter technique
colonies grow on blank in membrane filter technique
membrane
measurement of cell mass that is time consuming and not very sensitive
dry weight
quick easy and sensitive version of measuring cell mass
turbidometric measures (light scattering)
growth in an open system, continual provision nutrients, continual removal of wastes and cells
continuous culture
rate of removal of medium from vessel
rate of incoming medium
device for continuous culture
chemostat
changes in blank concentrations in the environment may affect microbial cells
osmotic
these channels in membrane allow solutes to leave
mechanosensitive
most microbes like to stay slightly blank to the environment
hypertonic
grow optimally in the presence of NaCl or other salts at a concentration above about .2 M
halophiles
require salt concentration of 2M and 6.2M
extreme halophiles
measure of the relative acidity of a solution and is a measure of blank
pH, H+
microorganisms that grow optimally between pH 0 and 5.5
acidophiles
most microorganisms grow between 5.5 an 7 pH
neutrophiles
microbes that grow between pH 8.5 and 11.5
alkilaphiles
most microbes maintain internal pH near blank because extremes can blank them
neutral, denature
plasma membrane is impermeable to blank
protons
microbes can change pH of their habitat by secreting blank or blank waste
acidic, basic
microbes are blank so they cannot regulate their internal temperature
ambitherms
three cardinal growth temperatures of microbes
minimal, maximum, optimal
microbes in 0 - 20 degrees C
psychorophiles
0 to 35 degrees C microbes
psychrotrophs
20 to 45 degrees C microbes
mesophiles
55 to 85 degrees C
thermophiles
85 to 110 degrees C microbes
hyperthermophiles
most microbes are blank and live in warm blooded animals, soil, termperate conditions
mesophiles
smaller transport proteins, more alpha helices and less beta sheets, and more polar and less hydrophobic amino acids and fewer weak bonds are all adaptations of blank
psychrophile
usually live at 20/21% oxygen and will die in the absence of oxygen; can only do aerobic cellular respiration
strict aerobes
strict anaerobes but can use oxygen only when it is present at levels reduced from that in the air
microaerophiles
organisms that use some other method of energy other than oxygen
anaerobes
organisms that will die in the presence of any oxygen
strict anaerobes
organisms that can live in the presence or absence of oxygen and they do aerobic respiration when O2 is there and something else when oxygen is absent
facultative anaerobes
the toxic forms of oxygen can blank proteins and blank in microbes
damage, nucleic acids
in all living cells there are blank present to neutralize most of the toxic blank species
enzymes, oxygen
aerobes and facultative aerobes have the most blank enzymes
detoxifying
all strict anaerobes lack or have very low amounts of blank
oxygen dismutase
adversely affected by increased pressure, but not as severely as nontolerant organisms
barotolerant
require or grow more rapidly in the presence of increased pressure
barophilic
x rays and gamma rays are blank radiation and can cause blank at low doses and death at higher doses
ionizing, mutations
extremely resistant to DNA damage by radiation
Deinococcus radiodurans
wavelength most effectively absorbed by DNA is blank nanometers
260
visible light at high intensities generates blank oxygen
singlet
these protect many light exposed microbes from photooxidation
carotenoid pigments
most microbes grow attached to surfaces rather than blank
free floating
ubiquitous in nature in water and are slime enclosed communities of material
biofilm
biofilms allows microbes to be more resistant to blank and blank
radiation, antibiotics
prokaryotic cells in biofilms communicate in a density dependent manner called blank sensing
quorum