Micro-organisms and Health (week 5) Flashcards
what is the role of bacterial pili / fimbriaea
hair like structures that aid adhesion to host cells
what colour are gram positive bacteria and why?
purple - many layers of peptoglycen in cell wall: keeps purple stain in and drugs out
what colour are gram negative bacteria and why?
pink - few layers of peptoglycen, stain washes out
What type of bacteria is S. aureus?
Gram +ve coccus
What type of bacteria are Helicobacter and Campylobacter?
Spiral
What type of bacteria is E. Coli?
Gram negative bacillus
Name a gram negative coccus bacteria
Neisseria meningiditis
Neisseria gonorrhoea
What type of bacteria is C. diff?
Gram positive bacillus
Name a gram negative coccobacilli
Haemophilus
Bordetlla
Brucellla
Pasteurella
Describe how bacteria replicate by binary fission
cells divide to give 2 identical daughter cells, no exchange of genetic material
Describe how bacteria replicate by conjugation
Conjugation tube forms between 2 bacteria and plasmid DNA is passed from one to another. Does not create new bacteria but genetic material is exchanged
Describe how bacteria replicate by transformation
Plasmids picked up from environment surrounding bacteria
Describe how bacteria replicate by transduction
Transfer of genetic material via a viral vector
What is fungi cell wall made from?
Chitin
Name the 2 classes of disease causing fungi
Yeats
Filamentous moulds
What are helminths?
Parasitic worms
How do parasites reproduce?
Asexually through fission
What kind of nucleic acid does a virus contain?
DNA or RNA
Double or single stranded
Sense or antisense
Briefly describe the stages of viral replication
- Attachment / penetration of host
- Release genome from protein coat
- Produce early viral proteins
- Genome replication in host nuclues
- Produce late viral proteins - structural / capsid
- Assembly of virion
- Virion release
how do retroviruses replicate?
reverse transcriptase enzyme converts RNA to DNA, which is then integrated into host DNA
host replication system then used
How do prions cause disease?
Aggregate and cause misfolding of native proteins
Name some diseases caused by prions
Creutzfeld-Jakob
Bovine spongiform
Encephalopathy
Scrapie
What is the definition of microbiota?
All organisms in a given community
What is commensalism?
one organism benefits, the other derives neither benefit or harm
What is the types of bacteria are the most common bacteria found on the skin?
coagulase-negative staphylococci
staph aureus
What type of bacteria is found in the mouth flora?
viridians / oral staphylococci
How does vaginal flora differ pre and post puberty?
After puberty, circulating oestrogen causes glycogen production, meaning C. albicans can colonise
True or false: the majority of bacteria found in the large intestine are aerobes
False - they are anaerobes
How does normal microbiota aid metabolism?
synthesises secondary metabolites / vitamins e.g. vit K, vit B12
ferment unused energy substrates
How does normal microbiota help resist colonisation of other species?
environmental manipulation e.g. lowering pH
produce anti-bacterial agents e.g. colicins, bacteriocins, fatty acids, metabolic waste products
Which bacteria normally cause superficial abscesses
S. Pyogenes
S. auereus
What is the host response to endotoxins?
Severe sepsis / septic shock
Clinical features of infection
Activation of clotting cascade can lead to DIC
What is meant by ‘incubation period’ and ‘period of inactivity’
- period between infection with organism and manifestation of clinical features
- period during which transmissible organisms may be transmitted to another person
