/sci/ - Science & Math

Virusoids are circular single-stranded RNAs dependent on plant viruses for replication and encapsidation.[1] The genome of virusoids consist of several hundred nucleotides and does not code for any proteins.
Virusoids are similar to viroids in size, structure and means of replication (Rolling circle replication).
Virusoids, while being studied in virology, are not considered as viruses but as subviral particles. Since they depend on helper viruses, they are classified as satellites. In the virological taxonomy they appear as Satellites/Satellite nucleic acids/Subgroup 3: Circular satellite RNAs.
The term virusoid is also sometimes used more generally to refer to all satellites.

-wikipedia

didnt know these were a thing until I just read this right now

>>6929815
PST viroid genome

>>6929875
raph?!?! is that u? also nice pic.
this is an image of a viroid. cant believe that that thing can manage to evade imune system of plants and propogate

>>6925057
thats exactly what im telling you. and theyre coming for u. ull never see them coming and once u notice their effects its far to late.

>>6929751
very good question. although viruses seem like simpler "organisms" they are all host obligate parasites. so in my opinion they must have come after archaebacterium bec they need some form of host to propogate

pic related its the effects of Potato spindle tuber viroid

here is an interesting figure i found showing the entire genome of citrus exocortis (viroid). its insane that it carries enough information encoded in a genome no more than 350 bases long to replicate itself.

Fig. 2. (a) Nucleotide sequence and structure of CEVd variants. (i) CEVd-t (Semancik et al., 1993); (ii) CEVd D-92 (Semancik et al., 1994); (iii) CEVd D-104 (Semancik & Duran-Vila, 1999); (iv) CEVd D-87; (v) CEVd D-76. Nucleotide changes compared with D-92 are indicated. Molecular structures are presented as the minimum free energy form predicted at 24 °C (Zuker, 1989). The five structural domains T1, P, C, V and T2 (Keese & Symons, 1985), terminal repeated regions U1, U2, L1 and L2, the AGCU tetrads (horizontal bars) (Semancik et al., 1994) and the hairpin II (HPII) stems (Steger & Riesner, 2003) are indicated. (b) Modelling of the CEVd D-forms D-38 (i), D-40 (ii) and D-43 (iii), with quasicomplementary sequence insertions (hatched areas) compared with the D-92 sequence to complete a hypothetical stable structure of the minimum free energy form predicted at 24 °C (Zuker, 1989). Nucleotide changes compared with CEVd D-92 are indicated.

>>6924874
a viroid isnt exactly as u describe. viroids are naked ssRNA with no protein coat or membrane making them much smaller than a virus but still infectious particles.
a satellite virus is the closest thing to a virus that "preys" on another virus. for example the only way to get hepatitis D is if u already have hep B. this is due to the fact that hep
D needs some of hep B's proteins to propagate itself.

>>6924265
the seedy underbelly of our cellular society needs macrophges to police it. sometimes the criminal HIV pathogens send signals to bribe the macrophages to look the other way and then they take over without an amune response. this can cause a collaps of the society as a whole.

these viruses are organized criminals that need to be stopped!

>>6923886
good to know. i have no background in biology im just interested in the subject atm. looks like ur right about cryo TEM (or EM) and that these are not cryo images. thought they somehow generated a 3D model from the data obtained from cryo to make these.

looks like im all outa images to dump. I do however have this khan academy on viruses witch was what sparked my interest in the subject
https://www.youtube.com/watch?v=0h5Jd7sgQWY

>>6923735
ohh is that the stuff that cause deformations in babies?

>>6923719
jebus crapes, nature just wont give us a break.

>>6923712
yeah true. i wana 3D print one so bad.

>>6923684
great explanation. heres some nodamura virus for u.

>>6923660
yeah good point. not a chance ill get anything done on this 3 year old laptop. also keep ur pics coming i like em

>>6923633
because unlike cells viruses are made of a set number of amino acid bases creating crystalline protein shells around the genome. this results in a highly ordered structure

>>6923635
glad to help and i prob will go DL JMOL again now that u mention it and start playing around with some of these structures

>>6923607
lol i remember when it was all over the news here in canada a few years ago but then everyone forgot about it. Its not like west nile virus went away

the background of this image depicts the the way that the bases are paired in the (ssRNA) genome of rhinovirus. pretty cool that viruses dont need DNA and that their genome is not arranged in a double helix shape like ours is

>>6923591
i think they used to use x ray crystolography back in the day but now its cryo-EM like in this pic

heres a particularly cool virus called mimivirus. one of the largest ones known. note the smooth surface and the perfect 5 fold axis of summitry. also based on the scale in the image its around 4000 angstroms across

>>6923542
thanks for ur bump. in return i give u yellow fever