Viruses Have Its Unique Structural Features
Definition
Virus
A virus is a non-cellular particle composed of genetic material (DNA or RNA) enclosed in a protein coat called a capsid.
- A virus is a non-cellular particle composed of genetic material (DNA or RNA) enclosed in a protein coat (capsid).
- Viruses lack the structures and processes for independent life and can only reproduce by infecting a host cell.
- They are obligate intracellular parasites, depending entirely on host cells to replicate.
Core Features of Viruses
1. Small and Fixed Size
- Viruses range from 20 to 300 nanometers, much smaller than bacteria and cells.
- Their small size allows them to invade host cells and evade immune defenses.
- Viruses do not grow after assembly—their size is determined by capsid protein arrangement.
- Viruses are assembled inside host cells, much like a car is built in a factory.
- They do not grow or develop like living organisms.
2. Genetic Material: DNA or RNA
- All viruses contain one type of nucleic acid (DNA or RNA, never both).
- Genetic material varies:
- Single-stranded (ss) or double-stranded (ds)
- Linear or circular
- This genetic material directs the host cell's machinery to produce viral proteins and replicate the viral genome.
RNA viruses, such as coronaviruses, often mutate more quickly than DNA viruses because RNA replication lacks the proofreading mechanisms found in DNA replication.
