Archaea vs Bacteria-Major Differences

 

Archaea vs Bacteria-Major Differences

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Archaea Definition

Archaea is a group of primitive prokaryotes that based on their distinct characteristics form a separate domain from bacteria and eukaryotes.

·         The term ‘Archaea’ is derived from a Greek word, ‘archaios’ which means primitive or ancient, indicating the primitive structure of these organisms.

·         These organisms usually inhabit extreme environments like deep-sea vents, saline waters, hot springs, and even below petroleum deposits.

·         These are mostly anaerobic and live in low-oxygen environments. Most of the archaea cannot be cultured in laboratories and thus, have to be identified through culture-independent techniques.

·         Organisms in this domain might share some characteristics with both bacteria and eukaryotes. They have an incipient membrane-less nucleus like bacteria but share some genes, metabolic pathways, and enzymes that are also observed in eukaryotes.

·         However, these organisms also have some unique characteristics. The membrane lipids of archaea contain fatty acid linked to glycerol molecule by ether bond instead of ester bond as in bacteria and eukaryotes.

·         Because archaea inhabit many extreme environments, they tend to have distinct metabolic pathways as well as genes that support their survival. Halophilic archaea have a unique set of genes that limit the extent of osmosis, facilitating their survival.

·         Reproduction in archaea is asexual by budding, fission, and fragmentation. The usual division process of mitosis and meiosis does not take place.

·         Most archaea aid the process of biogeochemical cycles for various elements like carbon, nitrogen, and sulfur.

·         Many archaea are methanogens that utilize anaerobic cellular respiration to produce methane as a by-product.

·         Even though oxygen-generating photosynthesis doesn’t occur in these organisms, some of them (phototrophs) use sunlight as a source of energy.

Bacteria Definition

Bacteria are single-celled primitive organisms that form a domain of organisms diverse in shape, size, structure, and even habitats.

·         Bacteria are prokaryotes that have a membrane-less nucleus and lack many cell organelles, which make them simple in structure and function.

·         The domain Bacteria includes organisms that are found in many different forms of life from high mountains to inside the body of other organisms.

·         Some bacteria are beneficial that help in various purposes like antibiotics production, industrial use, and biogeochemical cycles. However, some are pathogenic organisms that result in mild to severe diseases.

·         Bacteria are the smallest living entities in the world and are microscopic. These organisms are observed under a microscope by performing a number of staining techniques.

·         Based on the staining techniques, bacteria are divided into Gram-positive and Gram-negative bacteria.

·         Almost all bacteria have a cell wall made up of peptidoglycan that protects the bacteria against harmful chemicals. The cytoplasm has few ribosomes and a membrane-less incipient nucleus containing the genetic material.

·         The membrane lipids in bacteria are composed of fatty acids bound to glycerol by ester bonds.

·         Bacteria also have a unique RNA called transfer-messenger RNA (tmRNA).

·         The genetic material in bacteria is DNA which is transferred to their offsprings via asexual reproduction.

·         Reproduction takes place through binary fission, budding, and fragmentation but different methods like transformation, transduction, and conjugation are available for the transfer of genetic materials.

 

Basis for Comparison	Archaea	Bacteria
Definition	Archaea is a group of primitive prokaryotes that based on their distinct characteristics form a separate domain from bacteria and eukaryotes.	Bacteria are single-celled primitive organisms that form a domain of organisms diverse in shape, size, structure, and even habitats.
Habitat	Most archaea are extremophiles and are found in extreme environments like the deep sea, mountains, hot springs, salt brine, etc.	Bacteria reside in different habitats ranging from soil, water to inside living, and non-living organisms.
Cell wall	The archaeal cell wall is made up of pseudopeptidoglycan and lack D-aminoacids and N-acetylmuramic acid.	The bacterial cell wall is made up of peptidoglycan consisting of N-acetylmuramic acid and D-amino acids.
Membrane lipid	The fatty acids in membrane lipids of archaea are bound to glycerol by ether bonds.	The fatty acids in membrane lipids of bacteria are bound to glycerol by ester bonds.
Glucose oxidation	Archaea do not use glycolysis or Kreb’s cycle for glucose oxidation but follow metabolic pathways similar to these.	Glycolysis and Kreb’s cycle are important metabolic pathways in bacteria for glucose oxidation.

Glucose oxidation	Archaea do not use glycolysis or Kreb’s cycle for glucose oxidation but follow metabolic pathways similar to these.	Glycolysis and Kreb’s cycle are important metabolic pathways in bacteria for glucose oxidation.
Photosynthesis	Archaea do not perform oxygen-generating photosynthesis but are phototrophs, that use sunlight as a source of energy.	Many bacteria containing photosynthetic pigments can perform photosynthesis to prepare their own food.
Types	Archaea are divided into different groups like Methanogens, Thermophiles, and Halophiles on the basis of their characteristics.	Bacteria are divided as Gram-negative and Gram-positive based on their response to Gram staining.
Flagella	Archaeal flagella, also termed archaella, are synthesized by adding subunits at the base.	Bacterial flagella are hollow and are assembled by adding subunits moving from the central pore towards the tip of the flagella.
Reproduction	Archaea reproduce by fission, budding, and fragmentation. Sporulation doesn’t occur in archaea.	Some bacteria are capable of forming spores that help them survive extreme conditions for a particular period of time.
tRNA	Thymine is absent in the t-RNA of archaea.	Thymine is present in the t-RNA of bacteria.
tmRNA	tmRNA (transfer messenger RNA) is found in archaea.	tmRNA is found in bacteria.
Chromosomes	Introns are present in the chromosomes of archaea.	Introns are absent in the chromosomes of bacteria.
RNA polymerase	RNA polymerase in archaea is complex with more than eight polypeptides. They might even have multiple RNA polymerases.	Bacterial RNA polymerase is simple, with four polypeptides.
Pathogenicity	Archaea are non-pathogenic.	Bacteria might be pathogenic or non-pathogenic.
Examples	Thermosphaera aggregans, Staphylothermus marinus, Sulfolobus tokodaii.	Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Salmonella Typhi.