Section 4 Final Exam Flashcards
(24 cards)
Giant viruses are called:
Nucelocytoplasmic large DNA viruses (NCLDVs)
NCLDVs facts
- 6 families
- large ds DNA geomes
- share sets of “core” genes
Phycodnaviruses have been found in ______ and show decline in performance on cognitive tests
brain
Mice that were infected with virus containing algae showed: (3 things)
1- decline in cognitive test performance
2- 1/3 had antibodies against the virus
3- showed changes in genes associated with cognitive function and immunity
algae that have chalk plates on the outside of their cells: __________
viruses that infect this chalk type of algae: _____________
coccolithophores
cocolithoviruses
coccolithophores form:
large blooms in ocean seen from space due to their chalky exterior
when blooms end, lots of cocolithoviruses are found in seawater
cocolithoviruses (ex. EhV-86) encode
proteins that synthesize the sphingolipid ceramide
sphingolipid ceramide from cocolithoviruses are involved in: (2 things)
1- forming lipid rafts in cells membrane to allow virus to exit
2- blocking the cells apoptosis pathway to allow the virus to keep replicating
effect of cocolithovirsues on climate
1- Lysis of these algeal cells releases volatile chemical DMS (dimethyl sulfide) that forms clouds
2- these clouds prevent sunlight to ocean and block phytoplankton growth
NEGATIVE FEEDBACK
3- white cliffs or Dovers made from liths come out
NCLDVs #2:
mimiviruses
mimi= mimicking microbe
mimiviruses infect:
amoeba cells
mimivirus strucrure
- star shaped at one vertex “stargate”
- multiple membrane layers
- long protein/sugar fibers that make it resemble bacteria
Under the stargate shaped there is ____ _________ and intead, it is filled with proteins that are involved in the first stages of infection
no DNA
once star-shaped vertex opens:
viral membrane and phagosome membrane fuse and DNA is released into cytoplasm
mimivirus replication and assembly happens in ______ _______ in the host cells cytoplasm and NOT in the nucleus like usual
viral factory
viruses released from edges of _____ _______
viral factory
how are viruses made in viral factories
DNA packaged into particles at the outside edge of the factory and it exits through a portal on the opposite end of the stargate opening
- capsids filled with DNA at outer edge of viral factories
speculated that mimiviruses can cause ___________
pnemonia
proposed that girus evolution traces back to __________ and the family tecivididae based on the presence of some conserved genes in tectiviruses polintons transposons virophages plasmids viruses and other viruses
bacteriophages
Where did giruses come from?
1- bacterium infected by tectivirus was a endosymbiont that became mitochondria
2- tectivirus became a “polinton” (type of transposon) that was encoded in the nucleus
3- polinton escaped the nucleus and gained some cellular genes
4- the escaped version swapped genes and became the progenitor of mega viruses
5- polintons evolved more and became virophages adenoviruses bidnaviruses etc
Mimiviruses genome
- larger than many bacterial genomes
- many genes that were never found in viral genomes (cellular genes)
- some translation genes but not enough to do it on its own
- gene got so big due to duplications on the ends of the genome
- many orphans (genes not found elsewhere
many of girus genomes contain different _____ _____ ______ within them
mobile genetic elements (MGE)
proposed that MEGs are symbionts within the viral genome as they assist the virus in _____-______ ______ when there is many viruses trying to infect the same cell
virus-virus competition
(MEG makes virus win, virus wins, and MEG gets more distributed SYMBIOSIS)
Two types of MGE
1- restriction/modificatiom systems: degrade other viral DNA and host DNA and use it for their viruses replication
2-Homing endonuclease introns: splice out from genome and into the competing virus inactivating its genes/proteins
