Learning about Bacteria

Bacteria come in many shapes and sizes, from minute spheres, cylinders and spiral threads, to flagellated rods and filamentous chains. Although generally less than 5 micrometers long (smaller than human red blood cells), bacteria are found practically everywhere and live in some of the most unusual and seemingly inhospitable places on Earth.

As prokaryotes, bacterial cells have few of the cell parts of typical cells.

Although there are many bacteria on Earth, they were not discovered until the late 1600s. A Dutch businessman and amateur microscopist, Anton van Leeuwenhoek, found them while looking at scrapings from his teeth. His microscope was not very powerful and he could not see any details, but Leeuwenhoek is considered to be the Father of Bacteriology.

This is Anton van Leeuwenhoek This is Anton van Leeuwenhoek. In the 1600s, he discovered bacteria in teeth scrapings. This is Leeuwenhoek’s drawing of bacteria.

Until recently, biologists grouped all bacteria together in a single kingdom on the basis of their similar cellular structure. However, although all bacteria look similar, some differ chemically. After analyzing the chemical differences, scientists have reclassified bacteria into two separate kingdoms - Archaebacteria and Eubacteria.

The word Archaebacteria means “ancient” bacteria The word Archaebacteria means “ancient” bacteria. They already existed on Earth for billions of years before dinosaurs appeared. Scientists think that Archaebacteria closely resemble Earth’s first life forms. Many Archaebacteria live in extreme environments such as hot springs and in sewage.

Eubacteria do not live in as extreme environments as Archaebacteria Eubacteria do not live in as extreme environments as Archaebacteria. However, they live everywhere else. Millions live in and on your body. They coat your skin and swarm in your nose. Don’t be alarmed! They are either useful or harmless to you.

Some Eubacteria are autotrophs that float near the surfaces of Earth’s waters. These bacteria use the sun’s energy to produce food and oxygen. Scientists think that billions of years ago autotrophic Eubacteria were responsible for producing the oxygen that created Earth’s atmosphere.

This is a cladogram showing the evolution of bacteria.

Bacteria are found nearly everywhere on Earth - in soil, rocks, Arctic ice, volcanoes, and in all living things. When you hear the word bacteria, you may think about getting sick. After all, strep throat, ear infections, and many other diseases are caused by bacteria. It is true that some bacteria cause diseases and other harmful effects.

Of all the microorganisms, bacteria are the greatest threat to food safety. Food handling practices are risky when they allow harmful bacteria to contaminate and grow in food.

Asexual reproduction- involves only one parent cell and produces offspring identical to the parent Sexual reproduction- involves two parents who combine their genetic material to produce a unique offspring