# The Domain Bacteria --- **Bacteria** is one of the three [[domains of life|domains]] of life, and one of the two groups of [[prokaryote|prokayotic]] organisms. Bacteria are the most simple yet abundant cells on Earth. They are relativly small in size which is useful for its large surface area-to-volume ratio. ![[bacteria.png]] To grow bacteria in a [[labs|lab]] setting, scientists grow colonies in [[microbial culture]]. ## Taxonomy of Bacteria: Arrangement and Shape ### Arrangement Bacteria often stick together in particular arrangements that we can use to identify them with. Bacteria naming conventions use these words as prefixes. arrangement | name ------------|------ singlet | mono- pair | diplo- chain/line | strepto- grape cluster| staphylo- ### Shape There are two common shapes and two uncommon shapes for the individual bacteria. shape | common? | singular | plural ----------|:-------:|----------|-------- circle/ball| yes | coccus | cocci rodlike | yes | bacillus | bacilli comma/S | no | vibrio | vibrios spiral | no | spirillum| spirilla ## Features Unique to Bacteria Bacterial [[genetics]] follow the same basic rules as the rest of biology, but do have some special features, such as the ability to perform [[horizontal gene transfer]]. Bacteria reporduce by a process called "binary-fission" The below picture shows a bacteria's chromosome that has been released from a "gently lysed" [[#E. coli]] cell. ![[DNA of bacteria.png]] As prokaryotes, and have no nucleus, but instead store their circular chromosomal DNA in a "nucleoid" region. Some bacteria have one or more threadlike structures called **[[flagella|flagellum]]** that gives them the ability to move around. Bacteria use a variety of unique methods to regulate the **[[bacterial membrane transport|transport]]** of molecules in and out of themselves. Bacteria have a **[[cell wall#Cell Wall in Bacteria|cell wall]]** that is similar to a [[plants|plant's]] cell wall, made up of a carbohydrate called [[peptidoglycan]]. Bacteria have an [[bacterial immune system|immune system]] dedicated to fighting off viruses, or [[bacteriophage|bacteriophages]]. ## Notable Bacteria ### Cyanobacteria **Cyanobacteria** or blue green bacteria are major contributes to the ecosystem, because they can fix nitrogen into a usable form. ### E. Coli **[[Escherichia coli]]** is a bacteria found in the human digestive system. It is small and grows quickly and often used in experiments. ___