Bacterial Division & Binary Fission
True or false: bacteria division increases size of organisms.
False; just increases #
What is the term for the time it takes for a population to double through one round of binary fission?
Doubling time
What is the term for the number of cells per unit volume?
Culture density
What is the name of the chamber that direct microscopic cell count uses?
Petroff-Hausser
What unit do we use when counting the number of viable cells capable of forming colonies on plates?
CFU (colony forming units)
True or false: binary fission is most common in bacteria
True
Binary fission shows what type of growth (doubles the # of cells each generation)?
Exponential
Log (exponential) phase
What is an advantage of a direct microscopic cell count?
It is inexpensive and quick
To be statistically valid, count plates need to have between ___ and ___ CFUs
30-300
What is the term for the division of the cytoplasm during the formation of a new cell?
Cytokinesis
What equation can be used to calculate the generation time?
g = t (time) / n (number of generations)
In which stage do cells lyse and release nutrients into the medium?
Death phase
What is a disadvantage of a direct microscopic cell count?
Immobilization of motile cells, need high cell count, can't distinguish between live and dead cells
What is the formula we use to calculate the original cell density using serial dilutions?
OCD = CFU x 1/DF x 1/PV
What is the name of the protein that directs cytokinesis?
If a single cell divides into 48 generations, how many cells will there be?
Nn = 1 x 2^48 = 2.8 x 10^14
True or false: in the stationary phase, growth completely stops.
False; growth rate slows
What is the other type of direct cell count (not direct microscopic cell count)?
Electronic cell counting device
Which type of plate count has colonies w/in the agar and on the surface?
Pour plate
The _____ forms the division septum that divides the 2 daughter cells in binary fission.
Divisome
What is doubling time dependent on?
Environmental conditions
True or false: in the lag phase, there is intense metabolic activity (protein synthesis)
True
Which type of plate count consists of adding 0.1 mL of a serial dilution to the surface of pre-poured solidified agar?
Spread-plate