Are Viruses Alive?

by ep23 (student)

Are Viruses Alive?

What is a Virus?

Viruses are very small microorganisms, much smaller than bacteria. They are among the smallest organisms known and consist of a fragment of genetic material inside a protective protein coat. Viruses can only reproduce inside host cells and as a result, they damage the cell when they do this. Once a virus has invaded a cell, it then takes over and makes copies of itself. Eventually the copies of the virus fill the whole host cell, causing it to burst open. The viruses are then passed out in the bloodstream, the airways, or by other routes.

Structure of a Virus:

‘A virus particle, also known as a virion, is essentially a ( or RNA) enclosed in a protein shell or coat. Viruses are extremely small, approximately 15 - 25 nanometres in diameter.’

Certain viruses contain ribonucleic acid (RNA), while other viruses have deoxyribonucleic acid (DNA).

Flu Virus (H1N1 Virus)

The nucleic acid portion of the viruses is known as the genome. The nucleic acid can be single-stranded or double-stranded; it could also be linear or a closed loop; it may be continuous or occur in segments.
The genome of the virus is surrounded by a protein coat known as a capsid, which is formed from a number of individual protein molecules called capsomeres. They are arranged in a precise and highly repetitive pattern around the nucleic acid. A single type of ...

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Certain viruses contain ribonucleic acid (RNA), while other viruses have deoxyribonucleic acid (DNA).

Flu Virus (H1N1 Virus)

The nucleic acid portion of the viruses is known as the genome. The nucleic acid can be single-stranded or double-stranded; it could also be linear or a closed loop; it may be continuous or occur in segments.
The genome of the virus is surrounded by a protein coat known as a capsid, which is formed from a number of individual protein molecules called capsomeres. They are arranged in a precise and highly repetitive pattern around the nucleic acid. A single type of capsomere or several chemically distinct types may make up the capsid.
Some viruses contain an envelope. An envelope is a membrane-like structure that encloses the nucleocapsid and is obtained from a host cell during the replication process. The envelope contains viral-specified proteins that make it unique. The envelope of certain viruses is a lipid bilayer containing glycoproteins set in the lipid. The envelope causes the virus to appear. Projections from the envelope are known as spikes. The spikes can sometimes contain essential elements that allow the virus to attach to the host cell.

Life Cycle of a Virus:

The virus binds to the host cell, this is called adsorption.
It then enters the nucleic acid of the host cell.
Viral components and enzymes are produced; this is called biosynthesis of viral components.
The viral components are then assembled into complete viral units (viruses fully develop)
The developed viruses are then released from the host cell into the bloodstream, airways, etc.

What is Life?

All living things have certain life processes in common. There are seven things that they need to do to count as being alive.

Movement – All living things move
Respiration – Getting energy from food
Sensitivity – Detecting changes in the surroundings
Growth – All living things grow
Reproduction – Making more organisms in one of two ways, asexual or sexual reproduction
Excretion – Getting rid of waste products
Nutrition – Taking in and using food

So are Viruses Alive?

To be accepted as alive, an organism must be able to perform all seven of the life processes. Viruses qualify under all of these categories except respiration and reproduction, for which they act as a parasite and require a host cell to do it for them. Without the host cell, a virus would only be a piece of a genetic molecule and not be able to do anything by itself; therefore it cannot be a living thing.

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