Do you have to study for a biology exam? Are you stuck in bed with the flu and would like to understand what kind of microorganism hit you and made you sick? Although bacteria and viruses trigger disease in humans in similar ways, they are actually very different organisms, with a great variety of different characteristics. Learning these differences can help you stay informed about any medical treatments you are undergoing and will give you a better understanding of the complex biology that takes place within your body. You can learn to distinguish bacteria from viruses not only by studying the basics about these organisms, but also by examining them under a microscope and learning more about their composition and function.
Steps
Part 1 of 2: Learning the Differences
Step 1. Recognize the basic differences
There are substantial differences between bacteria and viruses in their size, origins and their effects on the human organism.
- Viruses are the smallest and simplest life form of all; they are 10 to 100 times smaller than bacteria.
- Bacteria, on the other hand, are single-celled organisms that can live both inside and outside other cells and are able to survive even without a host. Viruses, on the other hand, are only intracellular organisms, that is, they insert themselves into the host cell and live inside it, modifying its genetic material, so that it reproduces only the virus itself.
- Antibiotics cannot kill viruses, but they are capable of killing most bacteria, excluding those that have become resistant to the drugs. In fact, the improper use and abuse of antibiotics has resulted in resistance to antibiotics by some types of bacteria; in this way the drugs are less and less effective against potentially harmful bacteria. Gram-negative bacteria are very resistant to antibiotic treatments, but some of them can still kill them.
Step 2. Recognize the differences in reproduction
To survive and multiply, viruses must have a living host, such as a plant or animal. Otherwise, almost all bacteria can grow and develop even on non-living surfaces.
- Bacteria have everything they need to grow and multiply, namely organelles, and usually have asexual reproduction.
- In contrast, viruses generally possess information, such as DNA or RNA, enclosed in a protein and / or cellulose membrane, but they need the elements of the host cell to reproduce. The virus attaches itself to the surface of the cell by means of its "legs" and injects its genetic material into it. In other words, viruses are not really "alive", but are essentially genetic information (DNA or RNA) that fluctuates until they encounter an ideal host.
Step 3. Determine if the body has beneficial effects on the body
Although it may seem hard to believe, in reality the human body is inhabited by a myriad of small organisms that live within it (but which are distinct entities). In fact, in terms of sheer number of cells, about 90% of microbial life and only 10% of human cells are present in most people. Many bacteria coexist peacefully within the body and some also perform very important tasks, such as creating vitamins, breaking down waste and producing oxygen.
- For example, an important part of the digestion process is carried out by a type of bacteria called "gut flora", which, among other things, also helps to maintain the pH balance in the body.
- Although people are more familiar with "good bacteria" (such as intestinal flora), there are actually also "good" viruses, such as bacteriophages, which "take over" the cellular mechanisms of bacteria and cause their death.. Researchers from Yale University in the United States have designed a virus that can help defeat brain tumors. Keep in mind, however, that most viruses to date have not been shown to perform any beneficial function for humans. It usually only causes damage.
Step 4. Evaluate if the organism has vital characteristics
While there is no clear and unambiguous definition of what constitutes life, all researchers agree that bacteria are undoubtedly alive. Otherwise, viruses could be considered a bit like "zombies": they are not dead, but they are certainly not alive either. In fact, viruses have some vital characteristics, for example they possess genetic material that evolves over time through natural selection and are able to reproduce by creating more copies of themselves. However, they do not have a cellular structure or a true metabolism of their own; they need a host cell to reproduce. In other respects, they are fundamentally not living. Consider these characteristics:
- When they do not invade the cell of another organism, they essentially have no functionality; no biological process takes place within them; they are unable to metabolize nutrients, produce or expel waste and cannot move on their own. In other words, they are very similar to inanimate material and can remain in this "non-life" state for a long time.
- On the other hand, when the virus comes into contact with a cell that it can invade, it attacks it and produces a protein enzyme that dissolves part of the cell wall so that it can inject its genetic material inside. At this point, since he "kidnaps" cells to make copies of himself, he begins to manifest an important vital characteristic: the ability to transfer his genetic material to future generations, creating more organisms similar to him.
Step 5. Identify the causes of common bacterial and viral diseases
If you have a disease and you know what it is, it is easy to know its bacterial or viral nature, just do a simple research on the disease itself. Among the main diseases caused by bacteria and viruses are:
- Bacterial: pneumonia, food poisoning (commonly caused by E. coli), meningitis, sore throat, ear infections, wound infections, gonorrhea.
- Viral: flu, chickenpox, common cold, hepatitis B, rubella, severe acute respiratory syndrome (SARS), measles, Ebola, papilloma virus (HPV), herpes, rabies, HIV (the virus that causes AIDS).
- Know that some diseases, such as diarrhea and the common cold, can be indifferently caused by both organisms.
- If you cannot accurately recognize your disease, it becomes more difficult to tell the difference between bacteria and viruses, because it becomes difficult to distinguish the symptoms of each of them. Both bacteria and viruses can cause nausea, vomiting, fever, fatigue, and general malaise. The best (and sometimes the only) way to tell if you have a bacterial or viral infection is to see your doctor. He will give you laboratory tests to determine the nature of the infection.
- One way to ascertain whether the problem is due to a virus or a bacterium is to evaluate the effectiveness of ongoing antibiotic treatments. For example, penicillin is only effective if you have a bacterial infection and is of no benefit in cases of viral infection. This is why you shouldn't take antibiotics unless your doctor prescribes them for you.
- There is no cure for major viral infections and diseases, such as the common cold, but you can take antiviral medications that help manage or limit the symptoms and severity of the problem.
Step 6. Follow this simple pattern to learn how to recognize the basic differences between bacteria and viruses
Although the differences between the two different organisms are greater than those listed below, these are still the most significant
| Body | Dimension | Structure | Reproductive method | Treatments | I live? |
|---|---|---|---|---|---|
| Bacteria | Large size (about 1000 nanometers) | Unicellular: peptidoglycan / polysaccharide cell wall; cell membrane; ribosomes; DNA / RNA float freely | Asexual. DNA duplication and reproduction by cleavage. | Antibiotics; antibacterial disinfectants for external use | Yup |
| Virus | Small size (20-400 nanometers) | Non-cellular: simple protein structure; no cell walls or membranes; no ribosome, DNA / RNA are enclosed in a protein coat | Invades the host cell by exploiting its reproductive mechanism to create viral DNA / RNA copies; the host cell produces new viruses. | No known cure. Vaccines can prevent disease; symptoms are treated. | Indeterminable. It does not meet the standard of living requirements. |
Part 2 of 2: Analyzing the Microscopic Features
Step 1. Look for the presence of a cell
Structurally, bacteria are more complex than viruses. Bacteria are single-celled organisms, meaning that each bacterium consists of only one cell. Otherwise, the human body contains many billions of cells.
- Viruses, on the other hand, have no cells; they are made up of a protein structure called capsid. Although the capsid contains the genetic material of the virus, it lacks the characteristics of an actual cell, such as cell walls, transport proteins, cytoplasm, organelles, and so on.
- Therefore, if you see a cell through the microscope, you know that you are looking at a bacterium and not a virus.
Step 2. Check the size of the organism
One of the fastest ways to recognize a bacterium from a virus is to check if you can see it with a normal microscope. If you are able to see it, it means that it is not a virus. The virus, on average, is about 10 to 100 times smaller than a common bacterium. The virus is so small that you cannot see it under a normal microscope, but you can only observe its effects on cells. You will need an electron microscope or another extremely powerful type to see viruses.
- Bacteria are always much larger than viruses. In fact, the largest viruses are only the size of the smallest bacteria.
- Bacteria have dimensions of the order of micrometers (from 1000 nanometers upwards). Conversely, most viruses don't get to 200 nanometers, which means you can't see them with a normal biological microscope.
Step 3. Check for the presence of ribosomes (and not that of other organelles)
Although bacteria have cells, they are not very complex. Bacterial cells do not have a nucleus and other organelles, with the exception of ribosomes.
- You can spot ribosomes by looking for small, round organelles. In the graphical representations of the cells they are drawn with dots or circles.
- Viruses don't have organelles, not even ribosomes. In fact, besides the protein capsid, some simple protein enzymes and the genetic material (DNA / RNA) there is not much else in the viral structure.
Step 4. Check the organism's reproductive cycle
Bacteria and viruses are not like most animals. They do not need sexual intercourse or exchange genetic information with another organism of the same type to reproduce. However, viruses and bacteria do not reproduce in the same way.
- Bacterial reproduction is asexual. In order to replicate itself, a bacterium duplicates its DNA, stretches and splits into two sister cells. Each cell has an identical copy of the "mother" DNA and is therefore a clone (exact copy). You can observe this process under a microscope. Each daughter cell will grow and eventually divide into two more cells. Depending on the species and external conditions, bacteria can proliferate very quickly. As mentioned earlier, this is a microscopic process that lets you know that you are looking at a bacterium and not a normal cell.
- Viruses, on the other hand, are unable to reproduce on their own. They need to invade another cell and exploit its replication mechanisms to create new viruses. Eventually there will be so many viruses that the invaded cell will burst and die releasing more new viruses.
