Act about 3.5 billion years old bacteria are one of the oldest living organisms in Earth. Considering the evolution of life, they are about as distantly related to humans as possible. That wow are they important to us. They are responsible for a range of diseases, including cholera, tuberculosis and the plague among others. But they aren't all bad. They are trillions of good bacteria living in your gut that are essential to your health. In fact, they are approximately 10 times more bacterial cells than human cells in your body. They can keep the produce vitamins, prevent tumor formation, help the immune system fight pathogens and protect against cross-nergents among other benefits. Bacteria cells are very small, much smaller than plant and animal cells. They are found practically everywhere on Earth and live in some of the most unusual and seemingly inhospitable places. As a result, they come in lots of different shapes and sizes. Bacteria are unicellular prokaryotes, as we saw in these two videos. Despite being very different shapes and sizes, they contain the same elements. As our prokaryotes, they do not have a membrane-bound nucleus. The DNA is in the cytoplasm, in the area known as the nucleoid. Bacteria have a flexible cell wall that protects him from physical damage and is exposed to the external surroundings. A flage in them that helps the bacteria to move. Bacteria have two types of DNA, plasma DNA and chromosomal DNA. The chromosomal DNA carries most of the genetic information. The plasma DNA forms small loops and carries extreme information such as resistance to antibiotics, production of toxins and tolerance to toxic environments. The ribosome is involved in protein synthesis. The pylene enable the bacteria to attach to hosts and surfaces like sea, in-case-dines and rocks. They are also involved in DNA exchange between bacteria. So they have the components of bacteria cells. As bacteria are prokaryotes, they do not have a true nucleus but lose DNA in the nucleoid. They also have loops of plasma DNA and a flangella and lots of pylene.