Lecture 8 Flashcards
(49 cards)
Which domains of life are infected by viruses?
Archaea, Bacteria and Eucarya (so all of them)
How are Archaea similar to Bacteria?
- Unicellular microorganisms
- Circular chromosomes
- No nucleus
Why are archaea different from bacteria? Like in what ways?
- Cell walls made of impermeable S layer of proteins
- Special phospholipids (to survive the harsh environments they live in)
- Complex translation initiation mimicking eukaryotes
- Use methionine to start translation unlike bacteria who use N-formyl methionine
- Histone-like proteins
- Complex RNA polymerase machinery
- DNA replication machinery alike eukaryotic counterparts
- Distinct ribosomal RNA sequences
- Live in extreme environments (volcanic hot springs, salt lakes, etc.)
What are some characteristics of viruses that infect archaea?
- Unusual morphology (lemon, droplet, bottle shapes, etc.)
- All have dsDNA as genome (one has ssDNA so far)
- Most have internal or external lipid envelopes (none of the bacteriophages have envelopes)
- Many are temperate viruses that integrate their genome into host cell DNA (no host lysis)
- Many do not have an identified DNA polymerase gene (use host DNA polymerase)
Tell me a dumb fact about virus names.
They’re often named after their shape (ex: droplet shaped, spindle shaped, etc.)
What was Frederick Twort’s contribution to phage history?
- 1915: observed “acute infectious disease of micrococci” before knowing it was phage
Felix d’Herelle’s contribution to phage history:
1917: Identified bacteriophages
Ruska H, Ruska E and von Borries B contribution to phage history:
1940: phage visualization by EM and beginnings of phage group (phages DO exist)
Hershey and Chase contribution to phage history:
1952: discovered that DNA is genetic material using phages (important advancement for molecular biology)
Luria and Delbrück contributions to phage history:
1943: mutations arise without selection, so they arise spontaneously independent of selection, but then selection works its magic (before not known if this was the case or if mutations occurred as a “side effect” of changing environments)
Arber, Nathans and Smith contributions to phage history:
1970: type II restriction enzymes isolated (also applied to problems of molecular genetics)
Fiers contribution to phage history:
1976: MS2 ssRNA genome sequenced
Sanger contributions to phage history:
1977: first phiX174 ssDNA genome sequenced
What year was the first lambda dsDNA genome sequenced and how?
1982 using phage-derived tools, restriction enzymes, T4 DNA ligase, M13 vectors, etc.
True or false: the sequencing approaches used with phages were also applied to sequence genomes from E coli to humans.
True, bestie!
Some discoveries between 1980s?
Abundance of phases in the ecosystem really appreciated
Appreciated the co-evolution of phages and bacteria (gene transfer)
How does CRISPR-Cas9 work? and when was it discovered?
- Adaptation: virus invades bacterial cell, new spacer is derived from virus and integrated into CRISPR sequence/Production of CRISPR RNA: CRISPR RNA is formed, CRISPR RNA guides molecular machinery to target and destroy viral genome(evidence of immune memory but obvi Dif mechanisms)
- 2007: CRISPR-Cas adaptive phage immunity demonstrated then in 2012: Cas9 RNA-guided nuclease for genome editing
2013 advancement in phage research?
PhagoBurn: phage therapy Phase I/II clinical trial initiated
Phage therapy is great because it only targets bacteria (not us) which you know beneficial with the ongoing AMR crisis and we’re kinda running out of options. It does have a certain tropism which CAN be challenging to figure out.
a) phage therapy directly killing pathogens
b) phage enzymes used to kill pathogens
c) biofilm dispersal with enzyme included in phage
d) Drug sensitization by making enzyme that is sensitive to drugs which can allow drug to do its thang when bacteria are resistant and don’t allow the drug to become active or whatever
What is a good perspective to consider when doing research? (very odd wording I know, but future Ximena if you think of something…change it)
“Inventive innovation cannot be generated solely through policies that preferentially fund low-risk strategic research”
- Applications with greatest impact are derived from curiosity-driven research on fundamental phage phenomena sooooo SERENDIPITY idk man
What is the origin of bacteriophage?
Comes from word (phagein) that means “to devour”
Give a dope definition of bacteriophage.
Obligate intracellular parasites that multiply inside bacteria using some or all of the host biosynthetic machinery.
Where can we find bacteriophages?
Ubiquitous in all natural populations of bacteria (so basically anywhere you find bacteria, there is definitely a bacteriophage somewhere around)
Just how cool are bacteriophages?
Most widely diverse and distributed entities (10 to the 31 fools on this planet)
Examples of ssRNA bacteriophages:
Leviviridae: MS2
INOviridae: f1 fd, M13
