Lecture 2 Flashcards
Pathogens and Parasites
What organisms cause disease?
-Bacteria
-Viruses
-Fungi
-Prions
-Parasites
-Transmissible Tumors
What pushes the boundary of what we call an organism?
Viruses & Prions
-not a form of cellular life
-do not metabolize
True or false: Archaea cause disease often
False
-They live in extreme environments so they do not survive/compete well in environments that bacteria and eukaryotes live in
What plays a key role in how relationship is determined (Parasitism, Mutualism, Commensalism)
Mode of transmission
What mode of transmission does mutualism have?
Vertical
-stays close to host
What mode of transmission does parasitism have?
Gets energy from being on/in body of host
-easily jumps/ mobile stages
-waterborne
What does transmission allow for a pathogen?
Ongoing survival of pathogen
-does not kill host, spreads to new host
How can we tell if a pathogen is responsible for a disease?
Koch’s postulates
What are Kochs postulates?
- Organism must be found in all diseased hosts and shouldn’t be found in healthy ones
- Organism must be isolated from diseases host and grown in culture
- Organism should cause disease when introduced to healthy host
- Same organisms must be re-isolated from inoculated host
Problems with Koch’s postulates
- Not everyone gets sick even if they have the pathogen
- Not all organisms can be cultured in a lab, only live in environmental niche
- Not all organisms are equally susceptible/ Ethically it’s wrong to introduce someone to a disease.
- Hard to re-isolate
Virus characteristics
Genetic material
Lipid envelope
Need host machinery to replicate → not considered alive
High mutation rates = evades immune systems
Few effective antiviral treatments
DNA viruses → low mutation rates
RNA viruses → high mutation rates → fast evolution
Baltimore classification
What is Baltimore classification?
How viruses replicate/ insert into DNA→RNA→PROTEIN cycle
What are realms?
similar proteins
What is the origin of viruses?
Progressive hypothesis: escaped mobile genetic elements
Regressive hypothesis: simplified parasites (lost ability to replicate on their own b/c so dependent on host)
Virus-first hypothesis: an entirely different branch of proto-life
RNA world hypothesis: simple RNA molecule that was able to make more of itself that could evolve and become more complex overtime
Viruses original living thing
Progressive hypothesis
escaped mobile genetic elements
Regressive hypothesis
simplified parasites (lost ability to replicate on their own b/c so dependent on host)
Virus first hypothesis
an entirely different branch of proto-life
RNA world hypothesis
simple RNA molecule that was able to make more of itself that could evolve and become more complex overtime
Viruses original living thing
How does bacteria spread disease
Bacterial toxins
How is vibrio cholerae a good example of transmission and bacterial toxin
-Produces toxin that kills commensal e.coli in gut
-Toxin binds causing a cascade resulting in fatal diarrhea and spreads bacteria
True or false: Bacteria cannot naturally make their own antibiotics
False
-Bacteria can make their own antibiotic
-Bacteria will make an antibiotic they are resistant to to in order to kill bacteria from different populations
Protists
Single celled eukaryotes
-polyphyletic
Prions
Misfolded proteins that cause other proteins to aggregate
-leads to total nervous system breakdown
-no genome/genetic info
Transmissible tumors
Down regulates MHC so they can grown in host that they do not genetically match
