Viral Structure Comparison — a labelled NEET Biology diagram with a definitions lexicon.
Viral Structure Comparison Labelled parts: Bacteriophage T4, Icosahedral head, dsDNA, Collar, Contractile tail sheath, Baseplate, Tail fibers, TMV, Helical capsid, ssRNA, Capsomeres, Adenovirus, Icosahedral capsid, Fiber proteins, Head about 100 nm, Length about 300 nm. A complex bacteriophage that infects specific bacterial species, characterized by its polyhedral head and contractile tail. FYI: T4 is a classic example of a tailed bacteriophage, known for its ability to lyse bacterial cells and release progeny phages. A geometric structure with 20 triangular faces, representing the protein shell (capsid) that encloses the genetic material of a virus. FYI: The icosahedral symmetry is the most common arrangement for viral capsids, providing maximum volume with minimal protein material. Double-stranded Deoxyribonucleic Acid, the primary genetic material found in the nucleus of eukaryotic cells. FYI: DNA replication occurs semi-conservatively, meaning each new DNA molecule consists of one old strand and one newly synthesized strand. A protein sheath surrounding the inner tail tube of certain phages (like T4), which contracts upon host cell recognition to inject the viral genome. FYI: The contraction of the tail sheath provides the mechanical force necessary for the phage to penetrate the bacterial cell wall. The hexagonal structure at the bottom of the phage tail, which anchors the phage to the bacterial cell surface and facilitates DNA injection. FYI: The baseplate often contains receptor-binding proteins that specifically recognize and attach to receptors on the host bacterial cell wall. Single-stranded Ribonucleic Acid, a type of nucleic acid that can serve as genetic material for certain viruses (e.g., retroviruses). FYI: Many RNA viruses must carry their own RNA-dependent RNA polymerase (RdRp) because host cells lack this enzyme. The protein subunits that make up the outer shell (capsid) of a virus, forming the protective protein coat. FYI: The arrangement and type of capsomeres determine the symmetry (e.g., icosahedral or helical) of the viral particle. A non-enveloped, double-stranded DNA virus characterized by its icosahedral capsid and fiber proteins used for attachment. FYI: Adenoviruses are common human pathogens that often cause respiratory and gastrointestinal infections. A protein shell structure with icosahedral symmetry, formed by the self-assembly of capsomeres, protecting the viral genome. FYI: This symmetry is highly stable and efficient, allowing viruses to maximize their genetic payload within a minimal protein structure. Protein projections found on the surface of certain viruses (like Adenovirus) that are responsible for initial attachment and recognition of host cell receptors. FYI: These proteins act as the primary attachment mechanism, determining the host range of the virus.