In 1977, Carl Woese and George E. Fox experimentally disproved this universally held hypothesis about the basic structure of the tree of life. Woese and Fox discovered a kind of microbial life which they called the “archaebacteria” (Archaea)





The basic difference in Eubacteria and Archaebacteria is based upon its cell wall structure and features related to DNA replication , transcription and translation machinery. Archaebacteria have ether linked membrane lipids with branched chains as compared to eubacteria

**Discovery of Archaebacteria**

Archaebacteria, also known as Archaea, were discovered by Carl Woese in the 1970s. Woese was a microbiologist who used molecular phylogenetic techniques to study the genetic relationships between organisms. He analyzed the ribosomal RNA (rRNA) sequences of various microorganisms and identified a distinct group of organisms that were significantly different from both bacteria and eukaryotes. These organisms were later named Archaebacteria.

**Features of Archaebacteria**

Archaebacteria differ from true bacteria (eubacteria) in several key features. These differences include:

**1. Cell Wall Composition:**
- Archaebacteria have a unique cell wall composition. While true bacteria have peptidoglycan in their cell walls, archaebacteria lack peptidoglycan.
- Instead, archaebacteria have a variety of different cell wall components, such as pseudomurein or S-layer proteins.

**2. Plasma Membrane Structure:**
- The plasma membrane of archaebacteria is composed of unique lipids called isoprenoid ethers or diethers. These lipids have a branched structure and are more stable than the ester-linked lipids found in bacterial and eukaryotic cell membranes.
- This structural difference allows archaebacteria to thrive in extreme environments, such as hot springs or acidic environments.

**3. Genetic Information Processing:**
- Archaebacteria possess several unique enzymes and proteins involved in DNA replication, transcription, and translation.
- These enzymes and proteins are distinct from those found in true bacteria and share more similarities with eukaryotes, indicating a closer evolutionary relationship between archaebacteria and eukaryotes.

**4. Metabolic Pathways:**
- Archaebacteria have unique metabolic pathways that allow them to survive in extreme environments.
- For example, some archaebacteria can use alternative sources of energy, such as sulfur or methane, instead of sunlight or organic compounds.
- Additionally, archaebacteria can produce methane gas as a byproduct of their metabolic processes, which plays a crucial role in the global carbon cycle.

**5. Ecology and Habitat:**
- Archaebacteria are known to inhabit extreme environments such as hot springs, hydrothermal vents, highly acidic or alkaline environments, and salt flats.
- They can survive in these extreme conditions due to their unique cell membrane structure and metabolic pathways.

In summary, archaebacteria are a distinct group of microorganisms that differ from true bacteria in terms of cell wall composition, plasma membrane structure, genetic information processing, metabolic pathways, and ecological habitats. These unique features allow archaebacteria to thrive in extreme environments and contribute to the diversity of life on Earth.