microbial growth Flashcards
how do microbes reproduce
binary fission
describe the process of binary fission
cell elongates and DNA is replicated, inward growth of PM and cell wall, septum divides the cell in two, cells separate
other than binary fission, what are some other reproductive strategies for microbes
budding, multiple fission, and exospore production
in what conditions is a bacterial growth curve produced
when cultures are grown in liquid medium in a closed culture system (ie when we don’t supply it with fresh medium)
what are the 5 phases of the bacteria growth curve
lag, log/exponential, stationary, death, long-term stationary
describe any changes in cell number during the lag phase
there is no change in cell number
how long is the lag phase + what affects the length
may be long or short depending on the bacterial species, the history of the culture, and the growth conditions
when might you have a short lag period
if you subculture your cells into a new tube with the same medium it was already using
when might you have a long lag period
if you use an old/injured culture to start, or if you subculture it into a different medium than it was already using
what happens in the exponential phase
lots of bacterial growth
describe the growth in the exponential phase
growth is constant (ie doubles)
how will you get a linear relationship when plotting the exponential phase
plot Log10 number of cells vs time
T or F: in the exponential phase, the bacterial is very sensitive to adverse conditions
true
why is bacteria the most sensitive to adverse conditions in the exponential phase
because they’re the most metabolically active during this phase so many processes are happening at once
describe the growth rate in the stationary phase
growth rate slows down (curve becomes horizontal)
