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Bacteria And Viruses: What’s The Difference?

Winter season is also flu season—the risk of viral infection is as high as ever, and now we have the H1N1 (swine flu) flu epidemic to worry

Red blood cells on an agar plate are used to d...

Red blood cells on an agar plate are used to diagnose infection. The plate on the left shows a positive staphylococcus infection. The plate on the right shows a positive streptococcus infection and with the halo effect shows specifically a beta-hemolytic group A. (Photo credit: Wikipedia)

about, on top of the regular flu strains of the season. H1N1 (swine flu) is now a global epidemic, raising alarm and calls for action. The flu, short for influenza, can be a seriously debilitating condition but the situation is graver with a doubling death rate due to its swine incantation. The unfortunate consequences are danger to the population and increased hysteria, and even if the situation is properly addressed the flu will always be a viral infection of concern because of its consistently mutating and infectious nature.

Many people conflate or confuse bacteria and viruses, but a viral infection is different from a bacterial infection. Bacteria are living organisms, while viruses are not, and bacteria can reproduce on their own, while viruses cannot—viruses depend on a host cell to replicate. Bacteria will feed off of our tissues and release substances, and actually most bacteria is good for us because the bacteria in our bodies help break down matter and kill parasites. However, a very small percentage of certain bacteria can release substances that are toxic to us. Viruses, on the other hand, lie around looking for cells to infect. When it finds a cell, it latches onto it and forces it to make many copies of the virus. When the cell outlives its purpose, it bursts and the virus copies spread to repeat the same process with other cells until the virus has considerably spread. The sickness we experience is a result of this process.

Bacterial infections can be treated by killing the bacteria with an antibiotic, but viruses technically can’t be killed. Either the immune system stops the process, or treatment prevents viruses from infecting cells rather than killing the viruses themselves. So while antibiotics are available to get rid of bacteria, the goal in combating viruses is to create a vaccine that prevents infection in the first place. We have vaccines for many diseases like rabies and tuberculosis today that wreaked havoc in the past when no such treatment existed. However, the flu virus is one that transmits very quickly and is constantly changing its self to survive. So even if a vaccine is discovered, the vaccine will no longer be useful when the virus has evolved. This is why the fight against viral infection will always continue to be a priority of public health.

The Differences Between Bacteria and Viruses

Bacteria are much bigger than viruses, and much more complex. A typical bacterium has a rigid cell wall containing a cell membrane, which holds the cytoplasm. Within this fluid are chromosomes (made up of DNA) that hold the instructions for making new bacteria and performing other functions. There may also be loose bits of DNA called plasmids floating in the cytoplasm, and ribosomes, which are used for copying DNA so the cell can reproduce. Some bacteria have threadlike structures called flagella that they use to move around.

Viruses are much smaller, with lengths measured in millions of a millimeter. All viruses are made up of a core of genetic material … nucleic acid, which is either DNA or RNA. This is surrounded by a protein coat. Some viruses may also be protected by an outer spikey layer called an envelope. That’s all there is to a virus! Viruses can’t even reproduce by themselves … they need to take over another cell and get it to do it for them.