On this Earth there are essentially two types of living organisms. Simple and complex – prokaryotes and eukaryotes. The main difference between these types of cells, is the fact that eukaryotes have a neat membrane around its nucleus and have complicated parts that allow them to accomplish complex metabolic tasks that nurture the organism which houses them. Its older sister, the prokaryote, lacks an internal membrane and the whole organism consists of just one cell (ex. Bacteria).
So how did the prokaryotic cell evolve?
It is believed that one primordial prokaryotic cell ate one of its fellow bacteria and kept the bacteria inside its wall. The trapped bacteria started acted like generator of power, the organelle that we know today as mitochondrion.
Both prokaryote and eukaryote cells have been studied intensely ever since they were first discovered and while it is thought that the eukaryote cell evolved from the prokaryote cell, there was never any palpable proof of such a thing.
That is until recently! The theory became a scientific fact in 1977, when an intriguing new branch from the prokaryotes family was discovered. It`s name is archae.
The archae is single-celled critter that is similar in structure to the bacteria (it doesn`t have a nucleus nor other structures) so scientists figured out that is must be within this family that the first eukaryotic cell appeared.
So they started searching for more arachae cells, specifically for a complex arachae cell that would contain various proteins with the signature of a eukaryotic cell. Keep in mind that in the 80s there was no mean of accurately generating and analyzing the genome of thousands of microcells.
Back to present times, near Siberia, on the ocean floor, scientists discovered a new group of archae, whose genome had never been studied. After finding almost all its proteins (about 175 proteins) they concluded that the amino acid sequences found in those proteins were just like the ones found in eukaryotic cells.
Since this particular type of archae was found near the ocean area called Loki`s castle, the scientists dubbed it Lokiarcaeota. The little Loki cell, was later found in the ocean floor near Japan and the scientists who found it there reported the same results.
It is thought that the Loki cell contains the necessary genes that allow one prokaryote to engulf a close-by cell and to trap it inside its membrane, but only time will tell if this is truly the missing link in the evolution of cells.
Image Source: npr.org
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