Like the bacteria, archaea lacked a nucleus and membrane-bound organelles and, therefore, were prokaryotic cells. However, when scientists compared the DNA of the two prokaryotes, they found that there were distinct differences. They concluded that there must be two distinct types of prokaryotes, which they named archaea and bacteria.
Even bacteria share some fundamental differences, they are still similar in many ways:
*They both are single-celled, microscopic organisms that can come in a variety of shapes (Figure below).
*Both archaea and bacteria have a single circular chromosome of DNA and lack membrane-bound organelles.
*Like bacteria, archaea can have flagella to assist with movement.
Obtaining Food and Energy
Most archaea are chemotrophs and derive their energy and nutrients from breaking down molecules in their environment. A few species of archaea are photosynthetic and capture the energy of sunlight.
Like bacteria, reproduction in archaea is asexual. Archaea can reproduce through binary fission, where a parent cell divides into two genetically identical daughter cells.
Archaea are prokaryotes, but they differ from bacteria in their DNA and biochemistry.
Most archaea are chemotrophs, but some are photosynthetic or form mutualistic relationships.
Archaea reproduce asexually through binary fission, fragmentation, or budding.