Human microbiota Flashcards
What percentage of cells in the human body are of human origin?
10%
What does it mean if a micro-organism is described as ‘virulent’ or ‘pathogenic’?
It causes disease
What are Koch’s postulates?
- The causative organism must be isolated from every individual suffering from the disease in question;
- The causative organism must be cultivated artificially in pure culture;
- When the causative organism is inoculated from pure culture, the typical symptoms of the infection must result;
- The causative organism must be recoverable from individuals who are infected experimentally.
What are the problems with Koch’s postulates?
difficulty of isolation of causative agent, impossible to grow some pathogens in artificial culture, ethical objections, animal models not sufficient
What type of parasites are viruses?
obligate intracellular parasites
What is the generic structure of a virus?
nucleic acid core wrapped in a protein coat (some also have an envelope)
What makes retroviruses unusual?
The virion carries an RNA copy of the genome but upon infection of host cell, a cDNA copy of the virus genome is made using the enzyme reverse transcriptase
What is the name of the units making up the protein coat of a virus?
capsomeres
Which special class of virus attacks bacteria?
bacteriophages
What are believed to cause spongiform encephalopathies?
prions
Are all fungi prokaryotic or eukaryotic?
eukaryotic
Most fungi have a cell wall made of what?
chitin
Define moulds
fungi that grow in mats of tiny filaments (hyphae) forming mats called mycelia
What are unicellular fungi?
yeasts
Name 2 common superficial infections caused by mould
ringworm and athletes foot
Name the 4 classes of protista
apicomlexa, flagella Protista, ciliate Protista, amoebae
Name a Protista that can cause vaginal infection
trichomonas vaginalis
What do bacterial cells lack?
membrane bound nucleus
Are bacteria prokaryotes or eukaryotes?
prokaryotes
What are the two most common shapes of bacteria?
cocci or bacilli
What does the gram reaction test in bacteria?
Their ability to retain a crystal violet-iodine dye complex
What does the envelope of a gram-positive bacteria mainly comprise of ?
30-40 layers of peptidoglycan
What is the outer leaflet of gram negative bacteria mainly comprised of?
lipopolysaccharide
Are gram positive or negative bacteria surrounded by fimbriae?
Gram negative
