Table of Contents
What is the biological makeup of a virus?
All true viruses contain nucleic acid—either DNA (deoxyribonucleic acid) or RNA (ribonucleic acid)—and protein. The nucleic acid encodes the genetic information unique for each virus. The infective, extracellular (outside the cell) form of a virus is called the virion.
How is a virus created?
Some viruses may have evolved from bits of DNA or RNA that “escaped” from the genes of a larger organism. The escaped DNA could have come from plasmids (pieces of naked DNA that can move between cells) or transposons (molecules of DNA that replicate and move around to different positions within the genes of the cell).
What is the biological purpose of viruses?
Viruses are not only abundant, diverse, and important for ecology, they play a significant role in the evolution of their hosts. In addition to the selective pressure that they exert on cell populations, as mentioned above, they foster the evolution of genes and genomes and mobilize genes across lineages.
Can a virus have both DNA and RNA?
Virus genomes We often think of DNA as double-stranded and RNA as single-stranded, since that’s typically the case in our own cells. However, viruses can have all possible combos of strandedness and nucleic acid type (double-stranded DNA, double-stranded RNA, single-stranded DNA, or single-stranded RNA).
What are the 4 main parts of a virus?
Viruses of all shapes and sizes consist of a nucleic acid core, an outer protein coating or capsid, and sometimes an outer envelope.
Does a virus have a life cycle?
The multiple steps involved in the virus propagation occurring inside cells are collectively termed the “virus life cycle.” The virus life cycle can be divided into three stages—entry, genome replication, and exit.
Why do viruses mutate?
As a virus replicates, its genes undergo random “copying errors” (i.e. genetic mutations). Over time, these genetic copying errors can, among other changes to the virus, lead to alterations in the virus’ surface proteins or antigens. Our immune system uses these antigens to recognize and fight the virus.
What is the oldest virus?
Smallpox and measles viruses are among the oldest that infect humans. Having evolved from viruses that infected other animals, they first appeared in humans in Europe and North Africa thousands of years ago.
What 2 things are typical viruses made of?
No matter the shape, all viruses consist of genetic material (DNA or RNA) and have an outer protein shell, known as a capsid.