Infection session 2 - Lecture 1 - pathogen classification Flashcards
(24 cards)
Name the four main micro-organisms causing human diseas
-viruses, bacteria, fungi, parasites
What are prions? Size?
- infectious agent, proteins that generate copies of themselves and spread from person to person.
- Responsible for mad cow disease
- Make holes in brain and destroy neurological function.
- Smaller than 10^-8 m
What is a virus?
- Small infectious agent that replicates only inside living cells of other organisms
- Has nucleic acid: can either be RNA/DNA and ss or ds
What is a bacteriophage?
a virus that infects and replicates within a bacterium, it is an important way of transmitting resistant genes between bacteria
Describe the structure of a virus
- Envelope (outside layer)
- Protein coat (inside layer)
- Spikes (on the envelope) –> for attaching to specific cell surfaces
- Nucleic acid inside
Give an example of a single stranded non-enveloped virus
Parvovirus 19
- Virus which can cause temporary suppression of bone marrow (in most people this is sub-clinical b/c RBCs last up to 120 days)
- this can be a serious issue for people who have RBCs lasting 30 days or less (genetic abnormality) –> parvovirus can cause a serious anaemia crisis
Give two examples of double stranded non-enveloped viruses
- Adenovirus
- Human papilloma virus (HPV) –> has the ability to cause cancer
Give two examples of double stranded enveloped viruses
- Herpes virus
- Hep B –> worldwide cause of liver cancer. It is a chronic infection that causes inflammation (active, not latent). Has to be transferred through contact with bodily fluids. Disease associated with poverty and intravemous drug use (sharing needles)
In the context of RNA viruses, what does icosahedral mean?
- Icosahedral = 20 face polyhedron
- Means it is globular shape (as opposed to helical)
What is the difference between RNA and DNA viruses?
- ss DNA viruses are much less common than ds DNA viruses, opposite is true for RNA
- Crucial difference in in their ability to synthesise proteins. DNA viruses have to transcribe their DNA into RNA in order to make proteins, RNA do that right away
What type of RNA virus is Norovirus? What does it cause?
-ss, positive strand (needs to be converted to negative strand before is read), icosahedral, non enveloped
What type of RNA virus is HIV?
- Single stranded, positive strand, icosahedral
- Causes AIDS (acquired immune deficiency syndrome)
What type of RNA virus is Ebola?
- SS, negative strand, helical enveloped
- haemorrhagic fever
What type of RNA virus is rotavirus?
- DS, icosahedral, non-enveloped
- Causes diarrhoea in children
Split the important pathogens into prokaryote and eukaryotes
- Prokaryotes: viruses, bacteria
- Eukaryotes: fungi (yeast/mould), parasites (protozoa/helminths)
Describe the bacteria structure
-What is important about prokaryotic organisms?
- they have non membrane around DNA (floats around)
- Have capsule (outer wall, provides lots of protection, made of polysaccharides, poor immunogen, have pili sticking out from them), cell wall and plasma membrane.
- Has flagellum, cytoplasm and DNA floating in it.
- has plasmids + ribosomes
What is the coccus shape? Spirillus shape? Bacillus shape?
- circle
- Spiral (lol)
- rods
Describe the possible arrangements of bacteria
- clusters (only get this in cocci, bacillus prefer to be in chains)
- chains
What color is gram negative? Why is it that way?
What color is gram positive What is it that way?
- Pink–> plasma wall is much thinner, so dye washes right off b/c it isn’t thick enough.
- Purple: has a thick peptidoglycan layer (holds in the purple stain)
What classification can you use wrt oxygen?
- Aerobes: can survive in presence of oxygen (can be obligate aerobes)
- Anaerobes: can survive in the absence of oxygen
Name 4 differences between eukaryotes and prokaryotes
-P: no nuclear envelope or nuclei, no membrane bound organelles, 70s ribosomes, have usually single chromosome (circular)
How can you divide yeast?
-Single celled vs multicellular
How can you divide parasites (with info we have so far)
- Protozoa (single celled): gardia, P falciparum
- Helmonths (worms, multi-cellular): schistosoma, taenia,
Give 4 possible (most common) consequences of Adenovirus infection
- Respiratory infection (droplets and aerosol transmission)
- Conjunctivitis (direct contact)
- Gastro-enteritis (fecal/oral transmission)
- UTI (transfer)
