Bacteria for Kids - What is a Bacteria?

What is a Bacteria?

Bacteria are very small living things that have only one cell.
Some scientists classify bacteria as plants, because some kinds of bacteria can make their own food from sunlight, like green plants do.
But there are many differences between plants and bacteria.
So many scientists say that bacteria belong to a separate kingdom of living things, which is called the monera kingdom.

There are thousands of different kinds of bacteria. 

Each bacterium is so small that you need a powerful microscope to see it.

These rod-shaped bacteria are on the head of a pin. The photograph is enlarged so much that the surface of the pin looks rough, not smooth.

Many kinds of bacteria are useful. 
They help living things to survive and be healthy. 
Some of the bacteria on your skin protect you from other tiny living things that might harm you.
Those in your intestines help to break down the waste products that your body eliminates. They even help to make vitamins that keep you healthy.

We use bacteria to make some types of cheese and yogurt.

Bacteria in soil and water help to break down animal droppings and the dead bodies of animals and plants. These all contain chemical elements, such as carbon and nitrogen.
Some bacteria help change these chemical elements into other substances. These substances can then be used again by other living things.

But not all bacteria are helpful. Some kinds of bacteria destroy healthy cells and cause diseases. 

Whooping cough and food poisoning are caused by bacteria.
Animals and plants suffer illnesses, too.
Anthrax, a cattle disease, is caused by bacteria.
Bacteria also cause certain kinds of rot and blight in plants.

How do bacteria feed?

Bacteria are surrounded by a thick cell membrane with no openings to take in solid food.
Some bacteria contain chlorophyll, which can make food with the help of sunlight. Others soak up fluids from the body in which they live.
Bacteria that live on rotting plants or animals use chemical proteins called enzymes.
These can turn the dead matter into simpler liquids.
The bacteria then soak up the liquid through their cell membrane.
In this rod-shaped bacterium, the nuclear body forms an area of the cytoplasm.