Chapter 5 Flashcards
Growth
increase in size of an individual, or the increase in number of cells
population size can be measured using: (4)
- total count of cells (dead of alive)
- viable count of cells (only culturable cells)
- turbidometric means (optical density via a spectrophotometer)
- cell components (dry weight, protein content, etc.)
Generation time
time for microbial cells to double in number
Septum
partitioning between daughter cells, pinches off to form 2 equal daughter cells
Budding division
unequal cell growth, totally new daughter cell
- simple, from hyphae, stalks, appendages
biofilms
attached polysaccharide matrix containing embedded bacteria
- sessile growth on surfaces
- planktonic cells attach -> production of sticky matrix
Microbial mats
multilayered sheets w different organisms in each layer
- hot springs, intertidal regions
Biofilms prevent:
- harmful chemicals (antibiotics) from penetrating
- protists from grazing
- washing away of cells
Exponential growth
growth of microbial populations where cell numbers double within a specific time
Generation time
(g)
- g = t/n
- duration of exponential growth / number of doublings (generations) during that duration
Growth rate constant
slope of the line, represents rate of increase in growth rate during natural logarithmic growth
growth equation
final # cells = initial # cells x generations elapsed
k = log10Nt - log10N0 / rise x t
Viable count
measures the cells in the culture that are capable of reproducing
optical density (turbidity)
a quantitative measure of light scattering by a liquid culture, increases with the increase in cell numbers
batch culture
a closed system, microbial culture of fixed volume
