What is Bacteria? Structure of Bacteria

Bacteria is a single celled organisms, called prokaryotes, which means their DNA is contained within a certain area of the cell called the nucleoid, but not enclosed. They are one of the oldest living things on earth, having been in existence for at least 3.5 billion years. A microscope is needed to see them.

It’s come in many shapes and sizes, including spheres, cylinders, threads, rods, or chains. They can be aerobic (those that require oxygen to survive), anaerobic (those that die when exposed to oxygen), and those that prefer oxygen but can live without it. That they were create their energy through light or chemical reactions are called autotrophs, and those that have to consume and break down complex organic compounds to obtain energy are called heterotrophs.

It enclosed by a rigid cell wall, which can vary widely in its composition, helping to distinguish between different species of bacteria. When exposed to a dye called a gram stain, gram positive microbes trap the dye due to the structure of their walls, while gram negative bacteria release the dye readily, because their cell wall is thin. Inside the cell wall sits all the components necessary for bacteria to grow, metabolize, and reproduce.
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Structure of Bacteria

They are single-celled microorganisms with the absence of the nucleus and other cell organelles; hence, they are classified as prokaryotic organisms.

They are also very versatile organisms, surviving in extremely inhospitable conditions. Such organisms are called extremophiles. Extremophiles are further categorized into various types based on the types of environments they inhabit:

  • Thermophiles
  • Acidophiles
  • Alkaliphiles
  • Osmophiles
  • Barophiles
  • Cryophiles


There are some bacteria which are beneficial in different ways. They are some benefits of bacteria:

  1. Convert milk into curd: Lactobacillus or lactic acid bacteria
  2. Ferment food products: Streptococcus and Bacillus
  3. Improving the body’s immunity system: Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria
  4. Production of antibiotics, which is used in the treatment and prevention of bacterial infections: Soil bacteria.

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