Protein coat around virus

What is structure of virus? The core of the virus is made up of nucleic acids, which then make up the genetic information in the form of RNA or DNA. The protein layer that surrounds and protects the nucleic acids is called the capsid.

A virus structure can be one of the following: icosahedral, enveloped, complex or helical. What are viruses made up of? A virus is made up of a core of genetic material, either DNA or RNA, surrounded by a protective coat called a capsid which is made up of protein. Sometimes the capsid is surrounded by an additional spikey coat called the envelope. Viruses are capable of latching onto host cells and getting inside them. Why is the capsid important? The essential functions of the capsid are to protect the functional integrity of the viral RNA when the virion is outside the host cell and to initiate the infectious process when a receptor on a suitable host cell is encountered.

What is the function of envelope? This lipid and protein structure is called the virus envelope, and is derived from the host cell membranes. The capsid and envelope play many roles in viral infection, including virus attachment to cells, entry into cells, release of the capsid contents into the cells, and packaging of newly formed viral particles.

Do all viruses have capsids? All viruses contain the following two components: 1 a nucleic acid genome and 2 a protein capsid that covers the genome. Together this is called the nucleocapsid.

In addition, many animal viruses contain a 3 lipid envelope. The entire intact virus is called the virion. Viruses can not exist independently of other organisms as they must take over a living cell in order to reproduce. A virus particle, also known as a virion, is essentially nucleic acid DNA or RNA enclosed within a protein shell or coat.

Viruses are extremely small, approximately 20 - nanometers in diameter. The largest virus, known as the Mimivirus, can measure up to nanometers in diameter.

By comparison, a human red blood cell is around 6, to 8, nanometers in diameter. In addition to varying sizes, viruses also have a variety of shapes. Similar to bacteria, some viruses have spherical or rod shapes. Other viruses are icosahedral polyhedron with 20 faces or helical shaped. Viral shape is determined by the protein coat that encases and protects the viral genome. The type of genetic material found in a particular virus depends on the nature and function of the specific virus.

The genetic material is not typically exposed but covered by a protein coat known as a capsid. The viral genome can consist of a very small number of genes or up to hundreds of genes depending on the type of virus.

Note that the genome is typically organized as a long molecule that is usually straight or circular. The protein coat that encases viral genetic material is known as a capsid. A capsid is composed of protein subunits called capsomeres.

Capsids can have several shapes: polyhedral, rod or complex. Capsids function to protect the viral genetic material from damage. In addition to the protein coat, some viruses have specialized structures. For example, the flu virus has a membrane-like envelope around its capsid. These viruses are known as enveloped viruses.

The envelope has both host cell and viral components and assists the virus in infecting its host. Capsid additions are also found in bacteriophages. For example, bacteriophages can have a protein "tail" attached to the capsid that is used to infect host bacteria. Viruses are not capable of replicating their genes by themselves. They must rely on a host cell for reproduction. As next generation sequencing and analysis continues to grow in its sophistication, scientists will continue building knowledge when it comes to viral genomes!

Gelderblom, H. Structure and classification of viruses. Baron Ed. University of Texas Medical Branch. Holmes, E. What does virus evolution tell us about virus origins? Journal of Virology, 85 , Knipe, D. Fields virology. Woolhouse, M. Human viruses: discovery and emergence. Update your browser to view this website correctly. Update my browser now. The Building Blocks of Viruses It is hard for scientists to know exactly when viruses first emerged, but we do know that viruses originated at least as early as the first cells, around 4 billion years ago.

The Viral Capsid A simple sketch of a virus: nucleic acid genome, surrounded by a protein coat capsid , additionally surrounded by a membrane envelope. References Gelderblom, H. Science Saturday. High School. Learning Resources. Each collection features resources to Know about, Show, Explore, and Relate to an engaging theme for learners and educators. Data for the People.