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Entry, or penetration, is the second step in viral replication. This step is characterized by the virus passing through the plasma membrane of the host cell. The most common way a virus gains entry to the host cell is by receptor-mediated endocytosis, which comes at no energy cost to the virus, only the host cell. Receptor-mediated endocytosis ...
In bacteria, there is one general RNA transcription factor known as a sigma factor. RNA polymerase core enzyme binds to the bacterial general transcription (sigma) factor to form RNA polymerase holoenzyme and then binds to a promoter. [6] (RNA polymerase is called a holoenzyme when sigma subunit is attached to the core enzyme which is consist ...
Purified RNA of a positive-sense virus can directly cause infection though it may be less infectious than the whole virus particle. In contrast, purified RNA of a negative-sense virus is not infectious by itself as it needs to be transcribed into positive-sense RNA; each virion can be transcribed to several positive-sense RNAs. Ambisense RNA ...
Prior to entry, a virus must attach to a host cell. Attachment is achieved when specific proteins on the viral capsid or viral envelope bind to specific proteins called receptor proteins on the cell membrane of the target cell. A virus must now enter the cell, which is covered by a phospholipid bilayer, a cell's natural barrier to the outside ...
The best-known RdRps are polioviral 3Dpol, vesicular stomatitis virus L, [7] and hepatitis C virus NS5B protein. Many eukaryotes have RdRps that are involved in RNA interference : these amplify microRNAs and small temporal RNAs and produce double-stranded RNA using small interfering RNAs as primers. [ 8 ]
Genome type and replication cycle of different RNA viruses. RNA viruses in Orthornavirae typically do not encode many proteins, but most positive-sense, single-stranded (+ssRNA) viruses and some double-stranded RNA (dsRNA) viruses encode a major capsid protein that has a single jelly roll fold, so named because the folded structure of the protein contains a structure that resembles a jelly ...
Transcription of mRNAs initiated by viral polymerase using cap snatching. The first step of transcription for some negative, single-stranded RNA viruses is cap snatching, in which the first 10 to 20 residues of a host cell RNA are removed (snatched) and used as the 5′ cap and primer to initiate the synthesis of the nascent viral mRNA. [1]
Reverse transcription is the transfer of information from RNA to DNA (the reverse of normal transcription). This is known to occur in the case of retroviruses, such as HIV, as well as in eukaryotes, in the case of retrotransposons and telomere synthesis. It is the process by which genetic information from RNA gets transcribed into new DNA.