Emerald Robinson: Hi! I'm Emerald Robinson, and in this "What Is" video, we're going to take a look at one of nature's smallest yet most influential organisms: bacteria.
Bacteria, sometimes called "prokaryotes," are microscopic single-celled organisms that lack a nucleus and other membrane-bound organelles.
Most bacteria have the same major parts: a protective cell wall, a cell membrane, and a strand of DNA. Many bacteria also have flagella, whip-like structures that help them move. And all bacteria reproduce by binary fission: they grow until they split into two new identical cells.
Bacteria are very diverse. They have adapted to live in every type of environment on earth, including areas of high heat, extreme cold, high acid or high salt content. They're round, rod, or spiral-shaped; some are easily wiped out by medicines, while some resist them.
Of the three large groups, or "domains," that biologists use to classify living organisms, bacteria make up two of them: archaebacteria and eubacteria. Archae, or "ancient" bacteria, have unique genes that enable them to get energy from unusual sources such as ammonia, methane, and hydrogen gas. Most bacteria, however, fall into the eubacteria domain.
While some bacteria can make you sick, most serve extremely important functions. For example, bacteria that live in your intestine help you digest food. Special bacteria called cyanobacteria make huge amounts of oxygen through photosynthesis for us to breathe. Humans even use bacteria for everyday purposes: bacteria help us make foods like yogurt and cheese, and some bacteria even play a crucial role in producing medicine.
If you're still not convinced that bacteria are important, consider this: 90% of the cells that make up your body are actually bacteria cells. They're an essential part of what make you, you.