intro to bacteria & viruses Flashcards
what is the gram stain appearance of gram positive bacteria ?
purple
what is the gram stain appearance of gram negative bacteria?
red
the two groups cocci and bacilli are bacteria describe their gram stain appearance
cocci-spherical
bacilli - rod shaped
what can you find on the cell surface of bacteria?
- penicillin binding site
2.peptidoglycan
3.lipopolysaccharides i.e lipopoly only in gram negative
describe the thickness of peptidoglycan in gram positive and gram negative bacteria
gram positive has a thick cell wall (peptidoglycan)
gram negative has a thin one
what gram bacteria contains the outer membrane (lipopolysaccharide?)
gram negative
what are frimbae and state its function?
thread like projections used for sticking to things (adherance)
how does bacteria replicate?
binary fission
what is a bacteriophage ?
a virus that parasitses a bacterium by reproducing inside of it
How do you view a colony of individual bacteria?
using ur eyes to view it on a solid medium/agar
What is used to identify strains within a species?
dna typing techniques
What are the key differences between gram positive and gram negative bacteria?
stain remains in gram positive where as it washes off in gram negative
gram postive has no outer membrane (lipopolysaccharides) but gram negative does
gram negative has wavy cell wall whereas gram positive has a smooth
how much peptidoglycan does gram positive and negative have?
70-80% in gram positive
10-20% gram negative
do gram positive bacteria contain porins?
no porins or hydrophilic channels occur in the outer membrane
state 3 possible shapes of a virus
icosahedral , complex or helical
(complex is neither helical nor icosahedral)
What are obligate intracellular pathogens?
can only replicate inside a host i.e a virus
Define virion
ineffective form of a virus
what surrounds nucleic acid in a virus molecule?
a capsid
What is common in all antiviral agents?
theyre are virostatic (stops virus from replicating/growing)
not virucidal(termination of virus)
What are the stages of virus replication?
1.attachment
2.uncoating (entry)
3.replication (of nucleic acid)
synthesis
4.assembly(like putting things together in jigzaw)
5.release
state the name of the method of viral transmission between animals to humans?
zoonotic
What are the consequences of viral infection?
-chronic infection
-latent infection e.g coldsaws so can come back
-transformation
how does genetic variation occur in bacteria ?
-spontanous mutation
-genetic transfer of DNA
what are plasmids?
circular DNA found within bacteria
