Sommario
Come si riproducono gli ARCHEA?
Tali microrganismi si riproducono esclusivamente in maniera asessuale, anche se sono presenti meccanismi di trasferimento genico orizzontale (TGO), attraverso il quale una cellula trasferisce del materiale genetico ad un’altra senza che questa ne sia la diretta discendente.
Come si dividono gli archei?
In base all’analisi del DNA, gli archaea sono raggruppati in tre phylum: Crenarchaeota, Euryarchaeota e Korarchaeota. Gli Euryarcheota sono i meglio conosciuti ed includono i metanoproduttori e gli alofili.
Do archaea have DNA?
All living things have DNA. That’s the set of directions that makes them work. Archaea (formerly Archaebacteria) are alive. So they do have DNA, but like the bacteria, their DNA is not in a nucleus. The DNA is not surrounded with a membrane like it is in the cells of plants, animals, fungi, algae, and protozoa.
What is the environment of archaea?
However, most well-characterized Archaea have been cultured from extreme environments that are very salty, acidic, alkaline, hot, cold, or anaerobic where they are sometimes dominant. Methanogenic Archaea have been detected in the mammalian gastrointestinal tract, but no archaeal species causing disease has been identified thus far.
Where do archaea initiate replication?
Archaea initiate replication at one (e.g., Pyrococcus abyssi) or multiple sites (S. solfataricus) in their circular chromosome. Archaea are a common component of prokaryotic freshwater plankton, but most have been unknown to limnology until recently.
How do Archaea reproduce asexually?
The Archaea are single-celled organisms with no nucleus or organelles. They reproduce asexually by fission or budding and no species are known to produce spores. Analysis of ribosomal RNA sequences has led to a classification of these organisms as separate from the Bacteria (Fig. 8.1).