Chapter 23 Flashcards
What is an ecosystem
The sum total of all organisms and abiotic factors in a particular environment
What is a habitat
Portion of an ecosystem where a community could reside. An ecosystem contains many habitats
What is symbioses
Relationships that microbes can establish with other organisms
What is parasitism
A relationship where one member in the relationship is harmed and the other benefits
What is mutualism
A relationship where both members benefit
What is commensalism
A relationship where one species benefits and the other is neither harmed nor helped
What is the microenvironment
The immediate environmental surrounding microbial cells. Ex. your mouth contains many microenvironments. Physiochemical conditions vary spatially and temporally
Describe the microbes feast-or-famine existence
Resources in natural environments are high variable. Bacteria on your teeth can be in the famine state most of the time because they have to wait for food to come to it. Once food is ingested and they can use it, they will feast and proliferate quickly before returning to their famine state
How do natural environments compare to laboratory environments
Growth rates in nature are usually well below maximum growth rates in laboratories. Competition and cooperation occur between microbes in natural systems
Why are surfaces important microbial habitats
Because nutrients adsorb to surfaces and microbial cells attach to surfaces
What are biofilms
Assemblages of bacterial cells that adhere to a surface and enclosed in an adhesive matrix excreted by the cells. Energy is required to form a biofilm
What is the matrix in biofilms made of
The matric is typically a mixture of polysaccharides
What are biofilms useful for
Biofilms trap nutrients for microbial growth and help prevent detachment of cells in flowing systems
What intiates biofilm formation
Biofilm formation is initiated by ATTACHMENT of a cell to a surface followed by expression of biofilm specific genes
What are biofilm specific genes
Could encode proteins that synthesize intercellurlar signalling (quorom sensing) molecules and initiate matrix formation
