Cell Lines
Biologists chose the word "immortal" to designate cells that are not subject to the Hayflick limit, the point at which cells can no longer divide due to DNA damage or shortened telomeres. Prior to Leonard Hayflick's theory, Alexis Carrel hypothesized that all normal somatic cells were immortal.
The term "immortalization" was first applied to cancer cells that expressed the telomere-lengthening enzyme telomerase, and thereby avoided apoptosis—i.e., cell death caused by intracellular mechanisms. Among the most commonly used cell lines are HeLa and Jurkat, both of which are immortalized cancer cell lines. Normal stem cells and germ cells can also be said to be immortal (when humans refer to the cell line).
Immortal cell lines of cancer cells can be created by induction of oncogenes or loss of tumor suppressor genes. One way to induce immortality is through viral-mediated induction of the large T‑antigen, commonly introduced through simian virus 40 (SV-40).
Read more about this topic: Biological Immortality
Famous quotes containing the words cell and/or lines:
“There’s not one part of his physical being that’s like that of human beings. From his warped brain down to the tiniest argumentative cell of his huge carcass, he’s unearthly.”
—Willis Cooper. Rowland V. Lee. Wolf von Frankenstein (Basil Rathbone)
“Scholars and artists thrown together are often annoyed at the puzzle of where they differ. Both work from knowledge; but I suspect they differ most importantly in the way their knowledge is come by. Scholars get theirs with conscientious thoroughness along projected lines of logic; poets theirs cavalierly and as it happens in and out of books. They stick to nothing deliberately, but let what will stick to them like burrs where they walk in the fields.”
—Robert Frost (1874–1963)