Growth and Reproduction in Prokaryotes Flashcards
bacterial cells do not divide by meiosis and mitosis. Instead, most bacteria grow asexually by a process known as ___
binary fission
Describe the process of Binary fission
bacterium copies it chromosome
elongates, and splits off into two daughter bacteria with a genetic makeup identical to the parental bacterium
when dormant bacteria are transferred to a fresh medium with plenty of nutrients, they spend some time switching their metabolic machinery from a dormant state called
lag phase
can last from less than an hour to days, depending on the species of bacteria
lag phase
during the ___ phase, the bacteria are actively undergoing binary fission
log phase
the bacteria double their numbers every ___ ____
generation period
can range from 20 minutes to days, depending on the species
generation period
as long as there are plenty of nutrients and little waste buildup, the bacteria will continue growing ___
exponentially
it is convenient to represent the growth of the bacteria on a ___ graph, because the numbers of bacteria increase very rapidly with each subsequent generation
logarithmic graph
after the bacteria have grown for a while and they are starting to deplete the nutrients in the growth medium, some of the cells begin to die
stationary phase
phase where number of cells dying = new cells
stationary phase
after the bacteria have depleted most of their nutrients and their waste buildup is too great, the bacteria begins to deplete in larger numbers than are made
what phase
death phase
if a cell is to survive, it must switch its metabolism back to a ___ state
dormant
increase in cellular constituents
growth
§ Increase in cellular constituents
that may result in: (2)
increase in cell number
increase in cell size
If ____ ____ at the back of
your throat, a sore
throat.
Streptococcus pyogenes
Growth of
microorganisms in
refrigerator shortens/lengthns the
shelf life of the food
shortens
can produce beer, wine, cheese, yogurt, and other products
bacterial growth
most bacterial chromosomes are shaped __
circular
proceeds in both directions from the origin
DNA replication
after DNA replication, what happens to the cell?
elongation
formation of cross walls between daughter cells and cells separate
septation
types of bacterial division (4)
Binary Fission
Budding
Certain actinomycetes by conidiospores
Fragmentation
is a complex molecular machine responsible for DNA replication, ensuring that the genetic material is accurately duplicated before cell division
replisome
time required for the population to double in size
generation (doubling) time
§ varies depending on species of microorganism and
environmental conditions
generation (doubling) time
range is from 10 minutes for some bacteria to several days for
some eukaryotic microorganisms
generation (doubling) time
generation time is calculated during the ___ phase
log (growth)
what temperature can speed up generation time
room temp
what temp prolong doubling time
lower temperature
Microbial populations show a characteristic type of growth pattern called
exponential growth
convert to logarithmic number if arithmetic number is 1024
3.01
convert logarithmic number 6.02 to arithmetic
1047128.548
formula for the number of generation
= log no. of cells (end) - log no of cells (start) / 0.301 (constant)
constant number for number of generation
0.301
generation time is calculated using
= time lapse in minutes or (min/generation) / number of generations
if 100 cells growing for 5 hours produced 1,720,320 cells:
what is the number of generations
14.07
if 100 cells growing for 5 hours produced 1,720,320 cells:
what is the generation time
21.32 min/generation
final cell count formula
initial cell count*2^number of generations
pastry chef accidentally inoculated a cream pie with six S. aureus cells. If S. aureus has a generation time of 60 minutes, how many cells would be in the cream pie after 7 hours?
768 cells
Clostridium and Streptococcus are both catalase-negative. Streptococcus grows by fermentation. Why is Clostridium killed by oxygen, whereas Streptococcus is not?
This happens because Clostridium and Streptococcus have distinct responses to oxygen due to their metabolic pathways and enzyme profiles. Clostridium is categorized as an obligate anaerobe, meaning it cannot live in the presence of oxygen as it lacks defensive enzymes such as catalase and superoxide dismutase resulting in oxidative damage and cell death. Contrastingly, Streptococcus is classified as a facultative anaerobe or microaerophile–it can thrive in both the presence and absence of oxygen. They contain partial enzymatic defenses against reactive oxygen species, allowing them to survive in low-oxygen environments. In terms of their metabolic processes, Clostridium relies on fermentation for energy while Streptococcus can switch between fermentation and aerobic respiration depending on oxygen availability, allowing for efficient ATP production
Flask A contains yeast cells in glucose–minimal salts broth incubated at 30°C with aeration. Flask B contains yeast cells in glucose–minimal salts broth incubated at 30°C in an anaerobic jar. The yeasts are facultative anaerobes.
Which culture produced more ATP?
Flask A produced more ATP than Flask B. This is because flask A uses aeration for aerobic respiration allowing yeast to fully oxidize glucose through glycolysis, the citric acid cycle, and oxidative phosphorylation. The theoretical maximum yield of ATP from aerobic respiration is 30 to 38 ATP molecules per glucose molecule. Flask B, on the other hand, utilizes an anaerobic environment, requiring yeast to rely only on fermentation for ATP production (the yield of ATP from fermentation is lower producing only 2 ATP molecules per glucose molecule).
Flask A contains yeast cells in glucose–minimal salts broth incubated at 30°C with aeration. Flask B contains yeast cells in glucose–minimal salts broth incubated at 30°C in an anaerobic jar. The yeasts are facultative anaerobes.
Which culture produced more alcohol?
Flask A (aerobic condition), yeast undergoes respiration which is more efficient for energy production but does not favor alcohol production. In flask B (anaerobic condition), yeast relies on fermentation to convert glucose into ethanol and carbon dioxide, which is less effective in terms of energy yield but produces a greater concentration of alcohol as a byproduct.
Flask A contains yeast cells in glucose–minimal salts broth incubated at 30°C with aeration. Flask B contains yeast cells in glucose–minimal salts broth incubated at 30°C in an anaerobic jar. The yeasts are facultative anaerobes.
Which culture had the shorter generation time
The culture with the shorter generation time is Flask A (Aerobic). This is because Aerobic conditions generally promote faster growth rates for facultative anaerobes due to the higher energy yield from aerobic respiration compared to fermentation, which occurs in anaerobic conditions.
Flask A contains yeast cells in glucose–minimal salts broth incubated at 30°C with aeration. Flask B contains yeast cells in glucose–minimal salts broth incubated at 30°C in an anaerobic jar. The yeasts are facultative anaerobes
Which culture had the greater cell mass
The culture with greater cell mass is Flask A (Aerobic). This is because the efficient energy production from aerobic respiration allows for more rapid cell division and biomass accumulation compared to the slower fermentation process in anaerobic conditions
Flask A contains yeast cells in glucose–minimal salts broth incubated at 30°C with aeration. Flask B contains yeast cells in glucose–minimal salts broth incubated at 30°C in an anaerobic jar. The yeasts are facultative anaerobes.
Which culture had the higher absorbance?
The culture with higher absorbance is Flask A (Aerobic). This is because in yeast cultures, absorbance at 600 nm (OD600) correlates with cell density; thus, the higher growth rate and biomass in aerobic conditions would result in a higher absorbance measurement compared to the anaerobic culture
As essential
nutrients are depleted or toxic products build up, growth ceases, and the
population enters the
stationary phase
longest time in the growth curve
stationary growth
soil bacteria would constantly be in ___ phase since the soil has a lot of nutrients
stationary
Cell synthesizing new components
what phase
lag phase
Cell synthesizing new components
for what reason (2)
replenish spent materials
adapt to new medium or conditions
some cases can be short or even absent
what phase
lag phase
lag phase can also depend on the ___ of the medium (is it selective or enrichment, or what temp is the medium in)
harshness
The general rule of thumb is that
microbes adapt to a shift to
improved conditions _______
rapidly than they do to a shift to
poorer conditions.
much more
Also called log phase or log
growth phase
exponential phase
Rate of growth and division is
constant and maximal
exponential phase
Population is most uniform in
terms of chemical and physical
properties during this phase
exponential phase
Bacteria from this stage would
be used for studies
exponential phase
Closed system population growth
ceases due to
§ Nutrient limitation
§ accumulation of a waste product.
§ Limited oxygen availability
§ Critical population density reached
§ Bacteria die off and liberate some
nutrients
stationary phase
§ no change in the number of viable
cells, active cells stop reproducing
or reproductive rate is balanced by
death rate
stationary phase
can last for a long period since microbes in microbes in nutrient-poor environments (like soils and many
aqueous environments) probably
spend most of their time in stationary
phase
stationary phase
Cell numbers begin to decline due to
§ DNA or protein damage or
§ perhaps exhaustion of energy reserves
§ Accumulation of toxic waste
what phase
death phase
Bacteria are dying off opposite to ___ growth phase
log
do bacteria die all at once?
no
two alternative hypothesis for death phase
cells are viable but not culturable (VBNC)
cells alive, but dormant, capable of new growth when conditions are right
fraction of the population genetically programmed to die
programmed cell death
can microbes regulate their internal temp?
no
temperature with minimum growth
minimum temperature
growth rate will spike into exponential growth with what temp
optimum temp
growth rate will slow down with what temp (after optimum temp)
maximum temp
major environmental factor controlling microbial growth
temperature
are the minimum, optimum, and maximum temperatures at which each organism grows
cardinal temprature
optimum is 15C
and max is below 20 C
what microbes
psychropiles
opt. 20C to 40C
what microbes
psychrotolerant
0 oC to 35 oC
which microbes
psychrotrophs
which is more tolerant of chaging temperatures
psychrotrophs
psychrotolerant
psychrotrophs
- optima in the 20 oC
to 45 oC range
mesophiles
s have optima from
45 oC to 80 oC
thermophiles
optima,
above 80 C
extreme thermophiles
which microbes has the optimum temp at room temp
mesophile
core temp of body
37 degrees
surface temp of the body
35 degrees
which have midrange temperature optima, are found in warmblooded animals and in terrestrial and aquatic environments in temperate and
tropical latitudes
mesophiles
have evolved to grow optimally under very
hot or very cold conditions
extremophiles
Organisms with cold temperature optima are called
psychrophiles
most extreme representatives inhabit permanently cold environments.
psychrophiles
have evolved biomolecules that function best at cold
temperatures but that can be unusually sensitive to warm temperatures
psychrophiles
Organisms that grow at 0ºC but have optima of 20ºC to 40ºC are called
psychrotolerant
Organisms with growth temperature optima between 45ºC and 80ºC are called
thermophiles
optima greater than 80°C
hyperthermophiles
These organisms inhabit hot environments up to and including boiling hot
springs, as well as undersea hydrothermal vents that can have temperatures in
excess of 100ºC.
hyperthermophiles
Thermophiles and hyperthermophiles produce heat-stable macromolecules,
such as
taq polymerase
which is used to automate the repetitive steps in the
polymerase chain reaction (PCR) technique.
Taq polymerase
