microorganisms classification taxonomy Flashcards
why is globalisation an important characteristics?
more opportunities for pathogens to spread from one location to the other
what is not included in the tree of life and why?
viruses and prions - they are infectious particles and do not fit the criteria for a living organism
when writing the name of an organism which is the only part with a capital?
genus
how is placement done on tree of life?
there are stains that are widely used in organism identification instead of classification - use DNA (not a stain), gram stain, cell shape, endospore, atmospheric preference, fastidiousness and key enzymes
what are bacteria?
they are single celled organisms that lack a membrane bound nucleus and are prokaryotes
what is the flagella?
it is responsible for locomotion - the number and location can vary - mono, lopho, amphi and peritrichous - used to propel the pathogens e.g. e. coli from urethra to bladder and for identification
what are the pilli or fimbriae?
they are structures that are exposed to the extracellular space that aid adhesion to host cells and colonisation - adhesion - invasion - infection and can act as a virulence factor
what are examples of pilli?
pap pilli in uropathogenic E coli, opacity protein of Neisseria gonorrhoea - can adheres to a specific substrate on cell surface - contributes to tissue tropism of certain pathogens
what is the capsule or the slime layer?
it is a polysaccharide tightly adhered if capsule or loosely if slime, material that protects the bacteria from phagocytosis, dessication and antibiotics
what are biofilms?
community of bacteria surrounded by extracellular polymeric substances
what are endospores?
metabolically inert forms of bacteria that are resistant to many forms of environmental stress - UV, temperature, antiseptics and dessication. Bacillus and Clostridium are genus examples
what is the difference between gram negative and positive bacteria?
outer membrane in gram negative
what are the four cell walls encountered in bacteria?
gram positive, negative, mycobacterial and no peptidoglycan (atypical)
what are examples of gram negative and positive?
negative: E coli and neisseria
positive: strepto and staphylococcus
what would you use for mycobacterial cell wall?
acid fast staining
what is an example of mycobacterial and no peptidoglycan cell wall?
no peptidoglycan - chlamydia
mycobacterial - mycobacterium
how can bacteria be divided into two or three groups?
based on ability to retain crystal violet- iodine dye complex - following acetone or alcohol treatment