What is Microbiology?


Microbiology is the study of tiny biological creatures invisible to the eye like bacteria, viruses, and other microbes. Although these organisms are too small to see, they still have a dramatic impact on our lives. Microbes exist all around us. They live in water, soil, on our bodies, and even the air we breathe.


Are Microbes Bad For Us?

The short answer is yes and no. Although people often associate microbes with dirt and disease, there are plenty of beneficial microbes too. In fact, most microbes are beneficial. As we’ll discover in the next section, some microbes can make us sick. However, most microbes fulfill a vital role on our planet.


For example, in humans, we have microbiota (communities of microorganisms) that live in our bodies. Microbiota helps us digest food and maintain a healthy immune system. Plants rely on nitrogen-fixing bacteria to transform nitrogen in the air into a compound they can use to produce chlorophyll. Without chlorophyll, plants wouldn’t be able to convert sunlight energy into the sugars they need for survival.


What Are Microbes?


If you’ve ever had a cough, running rose, and felt like you wanted to sleep all day, then you’ve experienced a virus in action. These organisms hijack our cells as part of their natural lifecycle. Viruses are unique because they can only replicate with the help of a host (you and me). They don’t have all the resources they need to survive independently, so they need to find those resources from host cells. The genetic code in a virus is made up of either DNA (like us) or RNA, and this code dictates what they should do when they reach a host cell. Once inside the host body, they hijack the cells they infect to use the host nucleus, proteins, and internal machinery.


A virus’s goal isn’t to make you sick; its ultimate purpose is to replicate, and making you sick is just part of the process. Once the virus has hijacked the cell, it uses its resources to make hundreds or thousands of copies of itself until the cell becomes overworked and exhausted. When this happens, the cell explodes, and tiny virus particles enter the surrounding cells, and the process happens all over again. When you get symptoms like a running rose, frequent sneezing, and a cough, tiny virus particles can spread to other hosts. Interestingly, because viruses can’t replicate independently, they aren’t considered alive in a biological sense – they’re the dormant robots of biology.


While viruses generally get a bad rep for wreaking havoc on our bodies, not all viruses are nasty. Some viruses help us fight off more dangerous viruses or can kill harmful bacteria.



Bacteria are single-celled organisms with a simple internal structure (they lack an organized nucleus). While bacteria are still tiny, they are much bigger than viruses. The smallest bacteria is around one million times smaller than a meter in length, but most viruses are at least 100 times smaller than this!


Bacteria sport some awe-inspiring numbers. It’s estimated that in one gram of dental plaque (the gunk that builds up on your teeth), there are as many individual bacterial cells as there are humans that have ever lived.


Here’s what you need to know about bacteria:

  • Bacteria come in many different shapes, including rods, spirals, and spheres.
  • Bacteria is all around us, in soil, water, the air, and our skin and bodies.
  • Most bacteria aren’t dangerous and actually play a vital role in the planet’s ecosystem. For example, a class of bacteria called decomposers helps break down dead plants and animals to create nutrient-rich soil needed for life.
  • Bacteria don’t have a nucleus or other specialized organelles (cell components) that we find in animal cells. However, they do have a cell wall, outer membrane, inner membrane, food supplies, chromosomes, and more.
  • The scientific name for bacteria is prokaryotes.


Scientists split Fungi into two categories, molds, which are multicellular, and yeasts, which are unicellular. Most fungi have microscopic threads called hyphae, which they dig into a food source. Once dug in, they release chemicals that will break down the food so the fungi can digest it. Fungi aren’t fussy microorganisms. They will eat anything that is (or was once) a food, including fruit, bird droppings, and dead animals.



The word protozoa means “little animal.” Why are protozoans like little animals? Because they can’t make their own food, so they hunt other organisms. Unlike bacteria (prokaryotes), protozoans are eukaryotes, meaning they have a distinct nucleus. This class of microorganism thrives on moisture, so they can typically be found anywhere there is soil, freshwater, or saltwater. The most well-known protozoa is an Amoeba – a single-celled organism that “crawls” and uses finger-like projections to catch food.



Algae can be multicellular or unicellular and are eukaryotes. They live in aquatic environments like ponds, swamps, marshlands, and the ocean. Algae make food through photosynthesis, much like plants, although the wavelengths of light they utilize and the chemical reactions at play do differ. Algae are responsible for generating a lot of the earth’s oxygen. Ever seen Kelp? Then you’ve seen algae.


Scroll to Top