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Self assembly of virus capsids follows two basic patterns: helical symmetry, in which the protein subunits and the nucleic acid are arranged in a helix, and icosahedral symmetry, in which the protein subunits assemble into a symmetric shell that covers the nucleic acid-containing core.
The viral genetic material can be composed of DNA or RNA, which can be either single- or double-stranded, or gapped (e.g., hepatitis B virus, HBV). Viral genomes can have a linear or circular topology, and for many viruses the genomic ends contain repeated sequences, chemical modifications, or secondary structures with regulatory functions [3] .
25 sie 2018 · A virus is a chain of nucleic acids (DNA or RNA) which lives in a host cell, uses parts of the cellular machinery to reproduce, and releases the replicated nucleic acid chains to infect more cells.
18 lis 2019 · Viruses are small submicroscopic, obligate intracellular parasites, which contains either DNA or RNA as genome protected by a virus-encoded protein coat called capsid. Viruses are mobile genetic elements, depends on metabolic and biosynthetic machinery of host cells for their propagation.
Viruses are much smaller than bacteria and consist of a single- or double-stranded nucleic acid (DNA or RNA) surrounded by a protein shell called a capsid; some viruses also have an outer envelope composed of lipids and proteins. They vary in shape. The two main classes are RNA viruses and DNA viruses.
The infectious virus particles, or virions, are composed of proteins and are surrounded in some species of viruses by a lipid membrane, which is referred to as an envelope; the particles contain only one kind of nucleic acid, either DNA or RNA.
Unlike the genomes of all cells, which are composed of DNA, virus genomes may contain their genetic information encoded in either DNA or RNA. The chemistry and structures of virus genomes are more varied than any of those seen in the entire bacterial, plant, or animal kingdoms.
