Animal virus !!!

[peacefulheart]

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Most viruses that infect animals:
A. enter the host cell via endocytosis.
B. do not require a receptor protein to recognize the
host cell.
C. leave their capsid outside the host cell.
D. can reproduce independently of a host cell.

The answer is A. I chose D.

In EK book, there are twoo statements that are very confusing.

1."Although viruses can reproduce through a process involving the transfer of genetic
information, they ALWAYS require the host cell's reproductive machinery in order to do so."
2."There also exists naked proteins called prions that cause infections in animals. Prions are capable of reproducing themselves, apparently without DNA or RNA."

According to the 2nd statement, does that mean animal virus can reproduce independently of a host cell?

thanks a lot.

 

[ur2l8]

No. Prions aren't alive. They are what cause BSE/mad cow disease. Very similar to Alpha/beta amyloid plaque deposition in Alzheimer's. There isn't necessarily genetic transfer, however, the disease can be transferred simply by getting one of those prions into your CNS where they can mess some stuff up pretty seriously. Btw, a prion is essentially a misfolded protein. Not an animal of any sort. Hope this helps. Ps.viruses can only reproduce in the host! Sort of a definitional answer

 

[image187]

yeah what the above poster said. A prion is a misfolded variant of a normal protein, and an animal (or human) can be affected by it through infection (eating "mad" cow, also reported through corneal transplantation), sponstaneous mutation of a gene coding for the normal protein, or inheritance (rare; example fatal familial insomnia). A prion is NOT an actual virus by a classical definition, it is a weird term combining the words "viron" and "protein", and it is more like an infectious protein particle. A virus attaches to the host cell via some sort of receptor which signals endocytosis, and ALL viruses require the hosts reproductive machinery in order to reproduce. HIV and HBV bring along with them their own reverse transcriptase but they end up stealing the cell's RNA polymerase and other stuff