Bacteria Lesson for Kids: Definition, Facts & Types

Instructor: Dacia Upkins

Dacia has taught all core elementary subjects for 14 years with a Master's degree in Urban Teacher Leadership.

In this lesson, you learn about some of the smallest living things on the planet. You will be able to tell what bacteria are, what it is made of, and provide some examples of bacteria.

What Are Bacteria?

Did you know that in your stomach right now is a whole civilization of living things moving around, eating, reproducing, and more? The world we see is full of very, very small creatures that we cannot see with our eyes. These are called microbes or microorganisms, which usually can only be seen with a microscope.

There are different types of microbes, but in this lesson we will focus on the ones called bacteria. Bacteria are known as the simplest living creatures and have been around for millions of years. They can thrive in almost any kind of environment, so they can be found everywhere, even on your eyeball!

What Do Bacteria Look Like?

If you were to view bacteria under a microscope, you would observe some major parts that they all have. On the outside of the single-celled creature is a capsule, kind of like the plastic-looking shell on some medicines. Inside the capsule is a cell wall, which is another protective covering. Everything inside the bacteria cell is surrounded by a gooey substance called cytoplasm. Floating throughout the cytoplasm are ribosomes, which are used to help the cell function. Unlike most other cells, the bacteria do not have a nucleus, or control center. They move around by whipping their tail-like structure called a flagellum.

Like humans, bacteria can take on different shapes. Three, to be exact! Cocci-shaped bacteria look like spheres or ovals. Bacilli resemble a rod shape. And spiral-shaped bacteria may look either like a comma-shaped rod, a thick, rigid rod, or a thin, flexible rod.

Bacteria are protected by a capsule and travel by whipping their tail-like flagella.

Are They Really Everywhere?

There are few living things that can be found any and everywhere. Bacteria can survive in the hottest and coldest environments. They have been found in the boiling hot springs of Yellowstone Park, as well as inside ice in the Antarctic. They're also inside our bodies, our food, and in soil. In fact, if you scooped up one tablespoon of soil, you'd probably be looking at about 1 billion bacteria.

Are Bacteria Good or Bad?

That one tablespoon of soil discussed earlier contains bacteria that are used to decompose, or break down, dead plants and animals found in the soil. This helps the soil become rich with nutrients that are good for growing plants. That civilization of bacteria in your stomach right now helps our bodies break down the food we eat so that our bodies can get nutrients from it.

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