Mid Term 1 Review Questions (Part 1)

Question 1

What are prions?

Answer 1

acellular infectious agent that is only a protein

Question 2

How are prions formed?

Answer 2

when the scrapie/misfolded version of a prion (PrPsc) contacts the regular version of a cell (PrPc) is causes the normal protein to misfold

Question 3

What diseases do prions cause?

Answer 3

transmissible spongiform encephalopathies (TSEs)

Question 4

What happens to the impacted tissue of a prion disease?

Answer 4

misfolded proteins bind together inside the cell to form thread-like structures called fibrils. fibril-filled cells can’t function and eventually die, forming spaces in the brain that lead to the characteristic sponge-like appearance

Question 5

What are some general characteristics of prion disease? (3)

Answer 5

• untreatable
• fatal
• animal to animal, human to human transmission

Question 6

Why doesn’t a misfolded protein just fold back?

Answer 6

PrPsc (misfolded) assumes a beta pleated configuration, which is much more stable and resists our bodies efforts to degrade it

Question 7

How are prion diseases diagnosed? (4)

Answer 7

SendToDB
- by symptoms (often misdiagnosed)
- MRI, EEG, 14-3-3 protein levels in CSF
- post-death
- new blood test as of 2016 to test before symptoms start, uses PMCA

Question 8

what is PMCA?
what does PMCA stand for?

Answer 8

PMCA to find prions today.

how we detect prions. Protein Misfolding Cyclic Amplification. amplification technique to multiply misfolded proteins.

Question 9

how can plants play a role in prion contamination?

Answer 9

by taking up contaminated soil

Question 10

what is a “strain”?

Answer 10

related isolates of the same species which may harbor a few unique characteristics

Question 11

rDNA sequencing based definition of a species

Answer 11

16S sequencing identity. two species in prokaryotes corresponds to less than 95-97% 16S rDNA sequence identity. this is the most popular way of defining species.

Question 12

what is thought to be the origin of life on our planet?
where is thought to be the origin of life on our planet?

Answer 12

microbes under the sea in hypothermal vents. microbes exist in all three domains of life and outside of them!

Question 13

what are Koch’s postulates?

Answer 13

1. microorganism must be found in abundance in sick organisms and not in healthy ones
2. microorganism must be isolated from a diseased organism and grown in pure culture
3. cultured microorganism must cause disease when introduced to a healthy organism
4. microorganism must be isolated from inoculated organism and be proven to be identical to original pathogen

Question 14

what is the most important update to Koch’s postulates?

Answer 14

a nucleic acid sequence belonging to a pathogen must be detected. so we are trying to DETECT a nucleic acid, not SEE and GROW one.