A Student’s Guide to Bacteria

You can’t see them, but bacteria are everywhere. These tiny organisms float in the air, and they exist on surfaces, including your skin. These single-celled microorganisms are simple in nature, and they are similar to plant cells. Learning about the biology and science of bacteria can help you understand the differences between good and bad bacteria. While cleaning your skin and your house can help get rid of bacteria, you don’t want to get rid of all bacteria. The good types of bacteria can actually help you stay healthier.


Bacteria have three main shapes. They can be round like a ball, long and straight like a hot dog, and corkscrew-shaped. You might remember that animal cells have a nucleus in the center, which contains DNA and controls the cell. The nucleus is surrounded by cytoplasm, and a cell membrane is the outer layer that gives the cell its shape. Bacteria cells are different from animal cells because they often have cell walls, too, like plant cells have. Bacteria cells don’t have nuclei like animal cells. Even though bacteria don’t have nuclei, they still have DNA that controls what the cells do. Some bacteria have a capsule that protects the cell from invaders like white blood cells. Cell membranes sit just inside the outer cell wall. The cell walls also give bacteria their shape, but not every type of bacteria has cell walls. Bacteria may have one or more long tails, called flagella, which help them move.


Bacteria can reproduce very quickly, about every 20 minutes. Bacteria reproduce or multiply in a special process known as binary fission. When this happens, the original cell gets bigger by making an extra copy of everything inside of it. The bacterium then moves this extra copy to one end of the cell. Eventually, the extra copy splits off from the first cell, making two identical cells. Some cells reproduce a little differently by a process called “budding.” When this happens, the new cell grows alongside the parent cell until it gets to be the same size, then it pulls away. Every time a bacteria cell reproduces, it changes the DNA of the new cells a tiny bit. These small changes in DNA helps make the new bacteria cells stronger and more able to survive.

Helpful Bacteria

Some bacteria are beneficial, and they actually help keep the human body healthy. Good bacteria exist in the intestines, and they are important for the digestion process. These bacteria help the body use nutrients in food. Any parts of the food that the body doesn’t need are waste, and the body gets rid of these parts. You can make sure your intestines have enough good bacteria by eating foods such as yogurt and cheese. Scientists also use bacteria to make vaccines, which help fight diseases. The scientists use bacteria to grow specific viruses in a laboratory. They then study the virus to find its antigen, which is the substance that signals your body to fight off the illness. The scientists then add special ingredients to the antigen to make the body’s response stronger so it will win against the virus. Bacteria also live in the soil, helping to break down tissues to make the soil richer and better for growing plants.

Bad Bacteria

Bad bacteria are usually called germs or viruses, and these are the invaders that enter your body and try to make you sick. If you have germs on your fingers and you touch your eyes, nose, or mouth, the germs can get inside your body. From this point, they will attack your healthy cells by attaching themselves to them. If they succeed in this attachment, they may try to inject some of their DNA into the healthy cells. If this happens successfully, the healthy cells will start copying the virus. This is the way an illness can explode within the body. One of the best ways to avoid getting these germs inside your body is to wash your hands often. Try to remember not to touch your eyes, nose, or mouth, too. It’s also helpful to perform regular cleaning of surfaces in your house. Disinfecting light switches and door knobs, for example, can help remove germs from these places.

Bacteria Science Experiments

Learning about science and biology isn’t just about reading textbooks. You can also learn by playing games and performing experiments. You can even make science happen right in your kitchen or classroom by growing bacteria in a tiny dish. This can show you how quickly these cells reproduce themselves.