Bacteria are often maligned as the causes of human and animal disease. However that is true only for some bacteria. In fact bacteria are the basis for life. Without them no life at all would have been possible on our planet. Bacteria is a plural word. The singular for this word is “bacterium. They have one chromosome of double-stranded DNA in a ring and most are friendly. Only a few cause disease. But then what life form is there including plants and animals, a few of whom do not cause problems. Bacteria are life because they can multiply by duplication. However, they do not multiply by mating as higher life forms do. In the process, occasionally there are genetic mutations that are preserved creating new genes. Most chance mutations are eliminated by matching between male and female genes during multiplications in higher life forms.
Thus, bacteria are at the foundation of creation of life forms. The genes of more advanced creatures including humans are identical to bacterial genes and that is the source from which they have been derived. Bacteria can transfer their genes to other life forms through a variety of processes. Bacterial genes are enclosed in a cell wall but within that wall they do not have a protective nucleus to protect the genes further thus making the modification of bacterial genes much easier than the genes in the cells of higher life forms. A type of bacteria called cynobacteria, the basic cell type of plants is responsible for producing oxygen. Without them oxygen breathing life forms would not have been possible.
Although bacteria do not carry out sexual multiplication they do appear to enjoy sex of a different kind. They have appendages called pilli. This hollow, hair like structures made of protein allow bacteria to attach to other cells. A specialized pilus, the sex pilus, allows the transfer of plasmid DNA from one bacterial cell to another. That is how they transfer antibiotic immunity from one bacteria to another. Bacteria can acquire new genes by taking up DNA molecules (e.g., a plasmid) from their surroundings or from other bacteria.
Bacteria respond to variations in their environment by altering their gene expression pattern; thus, they express different enzymes depending on the carbon sources and other nutrients available to them as well as toxins in the environment that can damage them. Bacterial gene regulation is extremely efficient and the bacterial genome is highly organized. Bacteria appear to be adapt perfectly to a variety of environments, and they are ready to respond to whatever environmental changes they encounter by employing elegant and complex regulatory mechanisms. A modern theory of creation called Panspermia postulates that life has arrived on earth by a transfer of bacteria from outer space.