Viruses fact
Viruses
We are well acquainted with the remarkable features of living and nonliving entities. But, to the surprise of all, viruses are the simplest microbes, which are characterized by living and non-living characteristics. Simply put, they possess attributes of both aliveness and inanimate things. The name virus is derived from the Latin word for poison or toxin, virus. Scroll down to learn some of the amazing characteristics of viruses.
General Characteristics of Viruses
Viruses are very small in size, measuring approximately 20 - 400 nm (nanometer - one billionth of a meter). The average size is much smaller than the regular visible light wavelength. If you compare the size of bacteria and viruses, you will find the latter to be 10 - 100 times smaller than the former microbe. Discussed below are some of the notable characteristics of viruses, which you would like to know about these tiny microbes:
Virus Structure
Microbiologists study the structure of viruses with the help of a sophisticated electron microscope. The outermost covering of viruses is known as capsid (a protective protein coat), which encloses proteins and genome. Speaking about the virus shape, they may be filamentous, rod, helix, crystal, sphere and polyhedron along with extensions called antigens. These antigens help in identifying host and attaching them to the host organism.
Living Characteristics
The biological characteristics of viruses that define them as living entities are the ability to reproduce and carry forward their next generation. In fact, once inside their prospective host, viruses replicate at an extremely fast rate. Another living feature of viruses is mutation, in which an individual virus can undergo mutation under specific conditions.
Non-Living Characteristics
Similar to other non-living things, viruses do not grow or replicate on their own. In simple terms, they do not perform any metabolic activities, unless being triggered by the respective host organism. Viruses are acellular (no cells), meaning they are devoid of cytoplasm and cell organelles, both of which are recognizing features of living beings.
Virus Nucleic Acid
All types of viruses contain only one of the nucleic acids, either ribonucleic acid (RNA) or deoxyribonucleic acid (DNA) as their genome. None of the viruses contain both of them. The structure of the nucleic acid can be in a linear or circular form and is present in a single strand or double strand.
Virus Reproduction
The mode of reproduction in viruses is unique as compared to other living organisms. It reproduces only after infecting a host cell. As a virus enters a host organism, it attacks the cell and resides inside it. This is the reason why, we often say viruses are intracellular organisms. Once inside the host, the viral genome manipulates the host cell to synthesize protein coat and new viral nucleic acids. The virions (nucleic acid and capsid) are then assembled, after which the replicated viruses come out of the host organism.
Virus Infection
Virus can infect other microbes (e.g. bacteria), fungi, plants and animals. Those that attack only bacteria are classified as bacteriophages and macrophages are a group of viruses that infect fungi. They are obligate parasites, which may or may not kill host cell after replication. Viruses derive all the nutrients, chemicals and at times, enzymes from the host cells for survival and reproduction.
Virus Vs. Bacteria
So, how viruses differ from bacteria? The most distinguishing character between these two microbes is that viruses reproduce in a host organism, whereas bacteria have the ability to multiply with or without host. Thus, viruses cannot be studied in an artificial medium in laboratories. Viruses are intracellular, while bacteria are intercellular (living in-between cells). Unlike viruses which genomic content comprises only RNA or DNA, bacteria contain both types of nucleic acids. Last but not the least, some bacteria are beneficial to us; whereas all viruses are harmful, causing mild to severe diseases in plants and animals.
Related Info
This was an overview regarding what are some characteristics of viruses. Coming to nomenclature of viruses, they are named according to the disease that they cause in plant and animal. For example; flu virus causes flu disease, roseola virus causes roseola and poliomyelitis virus causes polio. With this, I hope you have cleared all your doubts pertaining to virus characteristics and how they differ from bacteria or other microbes in general.
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