Ch. 7.1 Microbial Growth Basics Flashcards
Define microbial growth
Cell division that produces new daughter cells and increases total cell populations
Why are biofilms a concern in the healthcare industry?
Because they make treating infections difficult and contribute to persistent infections.
How do biofilms form?
When free floating planktonic adhere to a surface.
Is binary fission sexual or asexual?
Asexual
Define budding
A form of asexual cell replication. Some fungi and bacteria reproduce this way. The difference between budding and binary fission is that the resulting cell from the bud is not the same size as the mother cell.
Define spore formation and its sexuality.
Sexual and asexual in fungi. Asexual in bacteria.
Define generation time
The time it takes for a particular species to divide.
Formula to calculate generation time:
generation time (in minutes) = growth time (in minutes)/number of generations
What are the four distinct growth phases of bacteria?
Lag phase- cells adjust to their environment
Log phase- exponential cell growth
Stationary phase- number of cells dividing equals number of cells dying
Death phase- cells die as waste accumulates and nutrients are depleted
What do cells do during lag phase?
They alter their gene expression in response to their new environment.
What factors determine the length of lag time?
Species cultured
Media used
Healthiness of cells in initial inoculum.
What effects the log phase?
What effects how long it lasts?
pH levels
temperature
salt concentration
oxygen concentration
nutrient availability and waste accumulation
What affects how long the stationary phase lasts?
What can be formed during this phase?
The amount of nutrients and the species being grown
Endospores
What affects the beginning of the death stage?
A critical point of decreased nutrients and waste build up.
What is a chemostat?
A device that is used to control the amount of cells as well as waste and nutrients in a culture. This allows for a continuous rate of cell growth and stops the cell death cycle.
