Classification, Structure & Replication of Micro-Organisms Flashcards
What is the major problem when treating conditions caused by microorganisms?
they will evolve and adapt to preventative measures
they become resistant, particularly to antibiotics
What is globalisation and why is it a problem?
the spread of a pathogen from one location to another
antibiotic resistance needs to be tackled globally and not just in the UK, as antibiotic resistant bacteria may be brought in from another country and allowed to spread
In the future, what is another problem for treating infections caused by microorganisms?
we are encountering new pathogens frequently and there may not be drugs which work against these
Why is the domain ‘archaea’ clinically insignificant?
no members of this domain will cause infection
Why are viruses and prions not included in the tree of life?
These “infectious particles” do not satisfy the criteria for a living organism
What are the 9 stages in classification?
Which 2 are the most clinically significant?
Genus and species are the most clinically significant

What are the different components involved in this name?


What is meant by:
Escherichia spp.
spp. means species
this can be used if you are talking about multiple species of the same genus
Why is it important to state the species as well as the genus of an organism?
There are multiple species within a genus that cause different diseases with very variable symptoms
It is not enough just to state the genus as you need to understand the type of infection that is being dealt with
What is the difference between classification and identification?
Classification:
this involves separating organisms into classes by looking at similar traits
Identification:
this involves the identification of the individual organism
What method is used to decide where to place bacterial species in the tree of life?
Looking at the DNA that encodes the 16S ribosomal RNA sequence
This gene is present in all prokaryotes, but is different in different species of bacteria
How can organisms be identified by their 16S sequence?
there are hypervariable regions that differ between microorganisms
these act like “barcodes” allowing the individual species to be identified
What 6 characteristics are commonly used in identification, rather than classification?
- Gram stain
- cell shape
- endospore
- atmospheric preference
- fastidiousness
- key enzymes
What type of cells are bacteria?
Why are they classified this way?
Prokaryotes
They contain no membrane-bound organelles and are single-celled organisms
Where is the DNA found within a bacterial cell?
a single chromosome is condensed within the middle of the cell
this is the nucleoid
What are the following features of a bacterial cell?


What is the function of the inclusion bodies?
they act as a food source
What is the purpose of the flagellae?
they are responsible for locomotion (motility)
if a bacteria does not have a flagella, it cannot move about
How can the different types of flagellae be classified?

A - monotrichous
B -lophotrichous
C - amphitrichous
D - peritrichous
What is a virulence factor?
a component of a microorganism that contributes to its ability to cause an infection
How can flagellae act as a virulence factor?
E. coli and Proteus spp. need the flagella for propulsion up the urethra and into the bladder
They are incapable of causing disease without the flagella
How can the flagellae be used in identification of certain pathogens?
The flagella itself is the H antigen
You can raise antibodies against the H antigen, allowing the bacteria to be distinguished from other similar organisms
What is the purpose of pilli/fimbriae?
They are exposed to the extracellular space and can aid adhesion to host cells and colonisation

How can pilli/fimbriae act as virulence factors?
They allow the organism to hold on to specific molecules
e.g. in a UTI, E. coli will hold onto specific sugar receptors on the epithelium of the bladder
this means that the urine cannot flush the organism away















