Difference Between Archaea and Bacteria

Archaea and Bacteria are two kinds of microorganisms that fall under the category of Prokaryotes. However, all archaea and bacteria are not prokaryotes. Earlier, archaea were classified as bacteria, but now it is outdated as it has been found that they both have different biochemistry and different evolutionary history.  

Archaea and Bacteria do not possess membrane found organelles or nucleus. They have similar size and shape.

Archaea: They are single-celled organisms that comprise cells with distinct properties that make them unique from the other two domains of life, namely Eukaryota and Bacteria.

They use numerous source of energy and display a diverse array of chemical reactions in metabolism. Based on reactions, they are categorized into nutritional groups. That is either dependent on carbon sources and energy. One group of archaea uses sunlight as a source of energy. They are termed as phototrophs. But any of these organisms do not possess oxygen-generating photosynthesis.

The other forms of archaea use inorganic compounds as a source of energy, namely ammonia or sulphur. They either include anaerobic methane oxidizers, nitrifiers, and methanogens. This reaction involves two compounds where one compound acts as an electron acceptor and the other as an electron donor. The energy that is released during the reaction releases ATP – adenosine triphosphate. It is one of the same basic processes that can be found in some of the eukaryotic cells.

Bacteria: They are single-celled organisms that usually live in a diverse environment. Bacterial DNA called the nucleoid are a twisted thread-like mass that flows free. They even possess a cellular structure that executes a range of circular functions that involves the transfer of energy to the transportation of proteins. Bacteria consist of plasmids which are a circular piece of DNA.

Bacterial cells consist of the inner cell membrane and an outer cell wall. Wherein some of the bacterias do not possess cell wall such as mycoplasmas. In some cases, bacteria may consist of a third protective outer layer in a cell called a capsule. Pili cover surfaces.

Explore more: Bacteria

 Bacteria and Archaea – The Major Differences

Archaea Bacteria
Reproduction and Growth
Asexual Reproduction, by the process of fragmentation, budding and binary fission Asexual Reproduction. Eubacteria produces spore to stay latent for several years.
Cell Membrane
Pseudopeptidoglycan Lipopolysaccharide/ Peptidoglycan
Metabolism Activity
Methanogenesis Autotrophy, Aerobic and Anaerobic Respiration, Fermentation and Photosynthesis.
Consists of three RNA Consists of single RNA
Thriving Habitat
Can sustain in extremely harsh environment such as oceans, hot springs, marshlands, hot springs and gut of humans They are generally found in soil, organic matter, earth’s crust, water, bodies of animals and plants, radioactive wastes, hot springs etc.

For more information and differences on Bacteria, Archaea and other related topics, keep visiting BYJU’S Biology website.

Frequently Asked Questions

1. What is archea? How are they different from bacteria?

Cell Membrane in arechea is made up of Pseudopeptidoglycan, where as in bacteria, it is made up of either Lipopolysaccharide or Peptidoglycan


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