tpes of parasites Flashcards
Derive nutrients from the cells or tissues of a living host
parasites
live on the body, helminths (flukes) and example
ectoparasites
endopaasitesand example
: live in the organs and tissues, helminths (worms
Intracellular parasites: and examples
: live within cells such as the leprosy bacillus and the syphilis spirochete
Obligate parasite and example
unable to grow outside of a living host, viruses
Nonsymbiotic relationships
Synergism- An interrelationship between two organisms that benefits them but is not necessary for survival
- cooperate together
- Examples: Gum disease, dental caries, and some bloodstream infections involve mixed infections that are examples of bacteria interacting synergistically.
Antagonism: an association between free-living species that arises when members of a community compete
- Common in the soil where mixed communities compete for space and food
Define biofilms
Mixed communities of bacteria and other microbes that are attached to a surface and each other.
How are biofilms formed
A “pioneer” colonizer initially attaches to a surface.
Other microbes then attach to those bacteria or a polymeric sugar or protein substance secreted by the microbial colonizers.
Attached cells are stimulated to release chemicals as the cell population grows.
Explain the structure of biofilms and mention 3 reasons why they are difficult to control
Structure- Large, complex communities form with different physical and biological characteristics.
The bottom may have very different pH and oxygen conditions than the surface.
Partnership among multiple microbial
l inhabitants
Cannot be eradicated by traditional methods
3 reasons they are difficult to control
1- mixed community
2-Microbes may be resiustant to chemicals/dyes
3- pH, O2 conditions vary.
4- large and complex community
5- bacteria becomes slow growing inside a biofilm
Define the term quorum sending and its importance in biofilm formation
Term given to the method where bacteria can interact with species far away and nearby (not just with their species)
- on formed in some bacteria
List the steps of binary fission
1)One cell becomes two
2) Parent cell enlarges
3) Duplicates its chromosome
4) Starts to pull its cell envelope together to the center of the cell
5) Cell wall eventually forms a complete central septum
The time required for a complete fission cycle, from parent cell to two daughter cells
Generation time or doubling time:
Generation: increases the population by a factor of
2
-As long as the environment remains favorable, the doubling effect can continue at a constant rate.
The length of the generation time is a measure of the growth rate of an organism
Average generation time = 30 – 60 mins
Shortest generation times = 10 – 12 mins
Mycobacterium leprae has a generation time of 10 – 30 days.
Environmental bacteria have generation times measured in months.
Most pathogens have relatively short generation times.
