Lecture 2

Question 1

What organisms cause disease?

Answer 1

-Bacteria
-Viruses
-Fungi
-Prions
-Parasites
-Transmissible Tumors

Question 2

What pushes the boundary of what we call an organism?

Answer 2

Viruses & Prions
-not a form of cellular life
-do not metabolize

Question 3

True or false: Archaea cause disease often

Answer 3

False
-They live in extreme environments so they do not survive/compete well in environments that bacteria and eukaryotes live in

Question 4

What plays a key role in how relationship is determined (Parasitism, Mutualism, Commensalism)

Answer 4

Mode of transmission

Question 5

What mode of transmission does mutualism have?

Answer 5

Vertical
-stays close to host

Question 6

What mode of transmission does parasitism have?

Answer 6

Gets energy from being on/in body of host
-easily jumps/ mobile stages
-waterborne

Question 7

What does transmission allow for a pathogen?

Answer 7

Ongoing survival of pathogen
-does not kill host, spreads to new host

Question 8

How can we tell if a pathogen is responsible for a disease?

Answer 8

Koch’s postulates

Question 9

What are Kochs postulates?

Answer 9

1. Organism must be found in all diseased hosts and shouldn’t be found in healthy ones
2. Organism must be isolated from diseases host and grown in culture
3. Organism should cause disease when introduced to healthy host
4. Same organisms must be re-isolated from inoculated host

Question 10

Problems with Koch’s postulates

Answer 10

1. Not everyone gets sick even if they have the pathogen
2. Not all organisms can be cultured in a lab, only live in environmental niche
3. Not all organisms are equally susceptible/ Ethically it’s wrong to introduce someone to a disease.
4. Hard to re-isolate

Question 11

Virus characteristics

Answer 11

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

Question 12

What is Baltimore classification?

Answer 12

How viruses replicate/ insert into DNA→RNA→PROTEIN cycle

Question 13

What are realms?

Answer 13

similar proteins

Question 14

What is the origin of viruses?

Answer 14

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

Question 15

Progressive hypothesis

Answer 15

escaped mobile genetic elements

Question 16

Regressive hypothesis

Answer 16

simplified parasites (lost ability to replicate on their own b/c so dependent on host)

Question 17

Virus first hypothesis

Answer 17

an entirely different branch of proto-life

Question 18

RNA world hypothesis

Answer 18

simple RNA molecule that was able to make more of itself that could evolve and become more complex overtime
Viruses original living thing

Question 19

How does bacteria spread disease

Answer 19

Bacterial toxins

Question 20

How is vibrio cholerae a good example of transmission and bacterial toxin

Answer 20

-Produces toxin that kills commensal e.coli in gut
-Toxin binds causing a cascade resulting in fatal diarrhea and spreads bacteria

Question 21

True or false: Bacteria cannot naturally make their own antibiotics

Answer 21

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

Question 22

Protists

Answer 22

Single celled eukaryotes
-polyphyletic

Question 23

Prions

Answer 23

Misfolded proteins that cause other proteins to aggregate
-leads to total nervous system breakdown
-no genome/genetic info

Question 24

Transmissible tumors

Answer 24

Down regulates MHC so they can grown in host that they do not genetically match

Question 25

What is a macroparasite? Can it make you sick?

Answer 25

-Macroparasites are a complex multicellular organism that adopted a parasitic life cycle like tapeworms, hookworms, lice, fleas, trematodes
-Macroparasites can make you sick if it overburdens you
more parasites → sick
less parasites → not really sick

Question 26

What are parasitoids?

Answer 26

Parasitoids are macroparasites, organisms that has young that develop on or within another organism (the host), eventually killing it