The bacteria contain several components in the cytoplasm which is surrounded by the plasma membrane.

The bacterial DNA is freely located in the cytoplasm in the area called the nucleoid. The bacterial DNA is usually circular and contains very few non-coding regions compared to eukaryotic DNA. The DNA content of the nucleoid varies between bacterial strains and can be adapted to the environment the bacteria live in. For example, it can code for proteins essential for survival under extreme conditions.

The DNA is transcribed freely in the cytoplasm and translated into proteins by 70S ribosomes. One of the most critical necessities for survival of living cells is protein synthesis. The 70S bacterial ribosome consists of a small 30S subunit and a larger 50S subunit.

Some bacteria also contain plasmids which are extra-cellular circular DNA molecules. Plasmids usually hold genetic materials that can give the bacteria a survival advantage in the environment they reside in. This can be antibiotic resistance genes or genes that can help the bacteria survive in extreme environments such as sulfur lakes or extreme cold.

Bacteria can live in environments that are low on nutrients. To accommodate external fluctuating nutrient levels, the bacteria can store nutrients in inclusion bodies in the cytoplasm. These can be highly variable and can contain carbohydrates, lipids, proteins or inorganic compounds.