Modeling Bacterial Growth Flashcards
many prokaryotes replicate via ____ and was first researched in_____
binary fission
*first researched in E.coli
list 3 other ways prokaryotes can divide other than binary fission
- budding
- multiple fission
~before cells are released they mature inside the parent cell - sporulation
~formation of spores (to survive harsh environments) that grow once conditions are favourable again
describe steps of binary fission (8
- chromosomes move to the middle of the cell (origin of replication)
- cell bulks up
~make sure has enough ATP, ribosomes, proteins - cell increases mass and increases DnaA protein, DnaA binds to origin of replication and initiates chromosome replication
- cell begins to widen along the plane of division (stretches)
- daughter chromosomes are separated and move to opposite sides of the cell - called partitioning or segregation
- once the cell is long enough FtsZ protein makes the Z ring in the middle (inside septum)
- FtsZ recruites enzymes to synthesize new cell wall/ membranes
- the Z-ring constricts, cell wall & membrane are synthesized and cells fully separate
how does the Z ring form in the right spot (2)
must have both to form!!
- Min system = FtsZ cannot form where there are high concentrations of Min proteins (at the poles) so develops in the middle
- Nucleoid occlusion = Z ring and nucleoid can’t be together so once they move to poles the Z ring can form in the middle
____ triggers the formation of the Z ring and septum
FtsZ
describe septum vs Z-ring
Z-ring - forms first and guides the process (to middle where cell will divide) + helps constrict
septum - the structure that actually divides the cells (builds up where the Z-ring is)
what is generation time and depends what what factors…..
the time it takes for the population to double in size
depends on….
- temperature
- type of growth media
- pH
list the 5 stages of the growth curve
- lag phase
- log phase
- stationary phase
- death phase
- long term stationary phase
what is the lag phase
- no growth / cells need to adapt to new culture
a bacterial growth in a ___ system will follow a strand are growth curve + describe
closed system
- not adding nutrients or removing wastes
what is the log phase
- cells are rapidly growing & dividing
- cells are the healthiest
- best time to get info from
what is the stationary phase and why
- number of cells levels off
~ number dying is equivalent to number still dividing - cells due to running out of nutrients / accumulation of waste products
( some might produce endospores for long term survival )
what is VBNC in stationary phase
viable but non-culturable cells
- enter dormancy until there’s a change in enviro conditions
describe programmed cell death in stationary phase
some commit suicide & others in the population feed off their remains
describe death phase
- decline in living (viable) cells
- deaths are greater than divisions
what is the long term stationary phase
- some cells start to adapt/evolve to the bad conditions (population levels off with small increases and dips)
what kind of scale is used for a binary fission growth curve and it is called what
1 logarithmic scale on the “population” axis
called semi-log scale
compare a regular scale vs logarithmic scale
regular - equal distances and increase by 1
log - used with regular or already log converted data
it is easier to interpret data from a _____ graph
linear graph
