May 7, 2015 04:12 AM
(This post was last modified: May 7, 2015 04:28 AM by Yazata.)
Procaryotic cells are small simple cells that don't contain cell organelles or have their genetic material enclosed in cell nuclei. Procaryotic cells include bacteria and archaea.
Eucaryotic cells are larger cells that have organelles inside them as well as nuclei that contain genetic material organized into chromosomes. They include the cells found in single celled protozoa, fungi, plants and animals.
Procaryotic cells are believed to be older and for much of the history of life on earth procaryotic cells were all there were. Bacteria were as complicated as life on Earth got, and evolution seems to have revolved around cell chemistry. (Bacteria and archaea have very diverse chemistries.)
Archaea are members of a group of procaryotic organisms that look and behave like bacteria and once were considered to be bacteria, but now are assigned to their own group due to fundamental chemical differences.
A big mystery concerns how eucaryotic cells first appeared. How did cells make the leap from one kind of cell to the other?
The news in this post is that microbiologists are reporting the discovery of a peculiar kind of archaea, discovered in undersea hydrothermal vents off the coast of Norway, that seems to contain some of the same genes found in later Eucaryotic organisms, but not in other Procaryotes. It isn't clear what those genes are doing in these more primitive cells.
These cells do not contain mitochondria or chloroplasts, eucaryotic organelles believed to have once been free-living procaryotic cells that took up a new life as symbiotes inside the eucaryotic ancestor cells. (Mitochondria and chloroplasts still have scraps of their own DNA.)
But one of the seemingly eucaryotic genes in these archaea codes for actin, a chemical with all kinds of uses in eucaryotic cells, including phagocytosis, the ingestion of food and materials into cells. So maybe these genes tell us something about how it is that the eucaryotes' procaryotic ancestor cells originally ingested the ancestors of todays's mitochondria and chloroplasts.
http://www.bbc.co.uk/news/science-environment-32610177
Eucaryotic cells are larger cells that have organelles inside them as well as nuclei that contain genetic material organized into chromosomes. They include the cells found in single celled protozoa, fungi, plants and animals.
Procaryotic cells are believed to be older and for much of the history of life on earth procaryotic cells were all there were. Bacteria were as complicated as life on Earth got, and evolution seems to have revolved around cell chemistry. (Bacteria and archaea have very diverse chemistries.)
Archaea are members of a group of procaryotic organisms that look and behave like bacteria and once were considered to be bacteria, but now are assigned to their own group due to fundamental chemical differences.
A big mystery concerns how eucaryotic cells first appeared. How did cells make the leap from one kind of cell to the other?
The news in this post is that microbiologists are reporting the discovery of a peculiar kind of archaea, discovered in undersea hydrothermal vents off the coast of Norway, that seems to contain some of the same genes found in later Eucaryotic organisms, but not in other Procaryotes. It isn't clear what those genes are doing in these more primitive cells.
These cells do not contain mitochondria or chloroplasts, eucaryotic organelles believed to have once been free-living procaryotic cells that took up a new life as symbiotes inside the eucaryotic ancestor cells. (Mitochondria and chloroplasts still have scraps of their own DNA.)
But one of the seemingly eucaryotic genes in these archaea codes for actin, a chemical with all kinds of uses in eucaryotic cells, including phagocytosis, the ingestion of food and materials into cells. So maybe these genes tell us something about how it is that the eucaryotes' procaryotic ancestor cells originally ingested the ancestors of todays's mitochondria and chloroplasts.
http://www.bbc.co.uk/news/science-environment-32610177