Viruses do not possess any machinery necessary for the purpose of their reproduction.
They only possess their genetic material enclosed within a capsid structure.
The capsid is constituted of glycoproteins.
They completely depend upon the components and organelles of the host cells whom they infect to help them carry out their reproduction process.
After infecting a host cell, the viruses hijack all the machinery and components of the host cell and use them for the purpose of transcribing their genetic material (DNA or deoxyribonucleic acid) to produce the virus-specific mRNAs (messenger Ribonucleic Acid).
These mRNAs are further translated into virus-specific proteins using the host-specific Ribosomes. These virus-specific proteins are required for replicating the viral genetic material and producing the capsid structure.
The virus-specific proteins and glycoproteins are synthesized by utilizing the raw materials from the host cells.
Transcription is the process by which an enzyme called RNA polymerase or DNA dependent RNA polymerase copies the protein coding region of the DNA (gene) in the form of an RNA sequence (mRNA).
The synthesis of the mRNA happens in the 5' to 3' direction. This mRNA is further recognized and converted into the amino acid sequence with the help of the Ribosome.
The amino acid sequence folds to give rise to the protein.
