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Siphoviridae
''Siphoviridae'' was a family of double-stranded DNA viruses in the order '' Caudovirales''. The family ''Siphoviridae'' and order '' Caudovirales'' have now been abolished, with the term siphovirus now used to refer to the morphology of viruses in this former family. Bacteria and archaea serve as natural hosts. The family had 1,166 species, assigned to 366 genera and 22 subfamilies. The characteristic structural features are a non-enveloped head and non-contractile tail. Structure Viruses in the former family ''Siphoviridae'' are non-enveloped, with icosahedral and head-tail geometries ( morphotype B1) or a prolate capsid (morphotype B2), and T=7 symmetry. Their diameters are around 60 nm. Members of this family are also characterized by their filamentous, cross-banded, non-contractile tails, usually with short terminal and subterminal fibers. Genomes are double stranded and linear, around 50 kb in length. Life cycle Viral replication is cytoplasmic. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphovirus
''Siphoviridae'' was a family of double-stranded DNA viruses in the order ''Caudovirales''. The family ''Siphoviridae'' and order ''Caudovirales'' have now been abolished, with the term siphovirus now used to refer to the morphology of viruses in this former family. Bacteria and archaea serve as natural hosts. The family had 1,166 species, assigned to 366 genera and 22 subfamilies. The characteristic structural features are a non-enveloped head and non-contractile tail. Structure Viruses in the former family ''Siphoviridae'' are non-enveloped, with icosahedral and head-tail geometries (morphotype B1) or a prolate capsid (morphotype B2), and T=7 symmetry. Their diameters are around 60 nm. Members of this family are also characterized by their filamentous, cross-banded, non-contractile tails, usually with short terminal and subterminal fibers. Genomes are double stranded and linear, around 50 kb in length. Life cycle Viral replication is cytoplasmic. Entr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caudovirales
''Caudoviricetes'' is a class of viruses known as tailed viruses and head-tail viruses (''cauda'' is Latin for "tail"). It is the sole representative of its own phylum, ''Uroviricota'' (from ''ouros'' (ουρος), a Greek word for "tailed" + -viricota). Under the Baltimore classification scheme, the ''Caudoviricetes'' are group I viruses as they have double stranded DNA (dsDNA) genomes, which can be anywhere from 18,000 base pairs to 500,000 base pairs in length. The virus particles have a distinct shape; each virion has an icosahedral head that contains the viral genome, and is attached to a flexible tail by a connector protein. The order encompasses a wide range of viruses, many containing genes of similar nucleotide sequence and function. However, some tailed bacteriophage genomes can vary quite significantly in nucleotide sequence, even among the same genus. Due to their characteristic structure and possession of potentially homologous genes, it is believed these viruse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escherichia Virus HK97
Bacteriophage HK97, often shortened to HK97, is a species of virus that infects ''Escherichia coli'' and related bacteria. It is named after Hong Kong (HK), where it was first located. HK97 has a double-stranded DNA genome. Assembly and maturation The major capsid protein of HK97, called gp5, cross-links upon maturation to form a chain-mail like structure. While DNA is being packaged into the capsid, the capsid expands by nearly 5 nm and changes from spherical to icosahedral in shape. The HK97 assembly pathway begins with self-assembly of gp5 into pentamers and hexamers. A protease, called gp4, cleaves gp5 at its N-terminus. Attachment of a portal protein, gp3, coupled with conformational changes leads to the formation of a prohead A prohead or procapsid is an immature viral capsid structure formed in the early stages of self-assembly of some bacteriophages, including the ''Caudovirales ''Caudoviricetes'' is a class of viruses known as tailed viruses and head-tail vir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmission Electron Microscope
Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a detector such as a scintillator attached to a charge-coupled device or a direct electron detector. Transmission electron microscopes are capable of imaging at a significantly higher resolution than light microscopes, owing to the smaller de Broglie wavelength of electrons. This enables the instrument to capture fine detail—even as small as a single column of atoms, which is thousands of times smaller than a resolvable object seen in a light microscope. Transmission electron micro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
