What is Bacteria? | Types, Definition, Structure, Function & Facts

What is bacteria?

Bacteria are tiny creatures all around us. We cannot see them without a microscope because they are so small, but they are in the air, on the skin, in the body, in the soil and everywhere in nature.

Bacteria are single-celled microorganisms. Their cell structure is unique in that they do not have a nucleus and most bacteria have cell walls similar to plant cells. They come in all sorts of shapes, including rods, spirals, and spheres. Some bacteria can “swim” using long tails called flagella. Others simply drag or slide along.

Are Bacteria Dangerous?

Most bacteria are not dangerous, but some are and can make us sick. These bacteria are called pathogens. Pathogens can cause disease in animals and plants. Some examples of pathogens are leprosy, food poisoning, pneumonia, tetanus, and typhoid fever.

Fortunately, we have antibiotics that help fight bad pathogens. We also have antiseptics to help us keep our wounds free of bacteria and antibiotic soaps that we use to bathe to keep bad germs away. Don’t forget to wash your hands!

Are Bacteria all bad?

No way. In fact, most bacteria are very useful to us. They play an important role in the ecology of the planet as well as human existence.

Bacteria in the Soil

Bacteria work hard in the soil for us. A type of bacteria, called a decomposer, decomposes dead plants and animals. It sounds gross, but it’s an important function that helps build soil and remove dead tissue. Another type of bacteria in the soil is the Rhizobium bacteria. Rhizobium bacteria help fertilize the soil with nitrogen that plants can use as they grow.

Bacteria in Food

Yes, there are bacteria in our food. It’s disgusting! Well, they’re not really that bad, and bacteria are used when making foods like yogurt, cheese, pickles, and soy sauce.

Bacteria in our Bodies

There are a lot of good bacteria in our body. One of the main uses of bacteria is to help us digest and break down food. Certain bacteria can also help our immune system protect us from certain organisms that can make us sick.

Parts of the Bacteria Cell (see picture)

The scientific name of the bacterial cell is prokaryotes. Prokaryotes are fairly simple cells in that they do not have a cell nucleus or other specialized organelles.

1. Capsula
2. Outer membrane
3. Periplasm and Cell wall
4. Cytoplasmic (inner) membrane
5. Cytoplasm
6. Ribosome
7. Reserve food supplies
8. Chromosome
9. Mesosome

Interesting Facts about Bacteria

There are about 40 million bacteria in one gram of soil.

Bacteria can survive in very harsh conditions, especially in areas deep in the earth’s crust and in radioactive waste.

There are about as many bacterial cells in the human body as there are human cells.

Bacteria are used to help the environment by treating wastewater and decomposing hydrocarbons from oil spills.

Some bacteria contain chemicals that can produce light. This is called bioluminescence.