HeLa cells are able to live beyond the Hayflick limit. There is a string of DNA at the end of each chromosome called telomere. This shortens a tiny bit each time a cell divides. In human cells, it can divide a certain number of times. Leonard Hayflick published a paper in 1961 showing that normal cells doubled about fifty times. A cell will soon stop dividing and therefore begin to die once all of its telomere is gone. For cancer cells, however, this is different because they can grow indefinitely. At first, many scientist believed that HeLa cancer cells could divide indefinately because of some error that happened in the mechanism that made a cell die when there are no telomeres left. However, a scientist at Yale had used HeLa cells to discover "that human cancer cells contain an enzyme called telomerase" (Skloot, 2010, p.217). This enzyme rebuilds the cancer cells telomeres. The presence of this enzyme meant that they could regenerate their telomeres indefinitely. That is why Henrietta's cancer cells are said to be immortal. HeLa cells chromosomes would never grow old and never die as well. Because of this is why HeLa was able to take over so many cultures. These cancer cells outlive and outgrew any other cells.
HI Lesley, based on what we have learned in AP Bio so far, what would you hypothesis would be a way to inhibit cancerous cells if they contain the enzyme telomerase?
I think if the tumor suppressor gene was active, it can inhibit cancerous cells if that contain the telomerase enzyme. This gene can inhibit the cell cycle. A tumor suppressor gene, or antioncogene, is a gene that protects a cell from one step on the path to cancer. When this gene mutates to cause a loss or reduction in its function, the cell can progress to cancer, usually in combination with other genetic changes. Cancer cells divide uncontrollably. This can be caused if the proto-oncogenes become oncogenes. Therefore I hypothesize that a cancerous cell will inhibit its growth based on the tumor suppressor gene.
Adding to what Lesley said, telomeres are sequences of DNA. When DNA is replicated during cell division in somatic cells, a short piece of RNA—called “primer”—helps it get started. Once a primer attaches itself to a DNA strand, DNA synthesis occurs. However, in the beginning, the primer does not attach itself to the very end of the parent DNA strand; therefore, the new copy is missing a section of DNA. Each time a cell goes through cell division, the copied DNA loses more of the end section also called telomeres. Telomeres help protect the DNA strand from getting shorter, and they also “protect chromosomes against degradation, fusion, and rearrangements during DNA replication” (“The importance of telomeres”). Just like the HeLa cells are able to construct the telomere ends again and again, egg and sperm also have the enzyme called telomerase, thus making them “immortal” (“Are Telomeres The Key To Aging And Cancer?”).
Are Telomeres The Key To Aging And Cancer? (n.d.). Retrieved January 18, 2015, from http://learn.genetics.utah.edu/content/chromosomes/telomeres/
The importance of telomeres. (n.d.). Retrieved January 18, 2015, from http://www.lifelength.com/importance-of-telomeres.html
Hela cells can be used to in cancer research, biological experiments or cell culture. But why this can be able to live beyond the Hayflick limit, which is the deadline for cell deat(apoptosis), scientists can not be so sure about that.
HeLa cells are able to live beyond the Hayflick limit. There is a string of DNA at the end of each chromosome called telomere. This shortens a tiny bit each time a cell divides. In human cells, it can divide a certain number of times. Leonard Hayflick published a paper in 1961 showing that normal cells doubled about fifty times. A cell will soon stop dividing and therefore begin to die once all of its telomere is gone. For cancer cells, however, this is different because they can grow indefinitely. At first, many scientist believed that HeLa cancer cells could divide indefinately because of some error that happened in the mechanism that made a cell die when there are no telomeres left. However, a scientist at Yale had used HeLa cells to discover "that human cancer cells contain an enzyme called telomerase" (Skloot, 2010, p.217). This enzyme rebuilds the cancer cells telomeres. The presence of this enzyme meant that they could regenerate their telomeres indefinitely. That is why Henrietta's cancer cells are said to be immortal. HeLa cells chromosomes would never grow old and never die as well. Because of this is why HeLa was able to take over so many cultures. These cancer cells outlive and outgrew any other cells.
ReplyDeleteHI Lesley, based on what we have learned in AP Bio so far, what would you hypothesis would be a way to inhibit cancerous cells if they contain the enzyme telomerase?
DeleteI think if the tumor suppressor gene was active, it can inhibit cancerous cells if that contain the telomerase enzyme. This gene can inhibit the cell cycle. A tumor suppressor gene, or antioncogene, is a gene that protects a cell from one step on the path to cancer. When this gene mutates to cause a loss or reduction in its function, the cell can progress to cancer, usually in combination with other genetic changes. Cancer cells divide uncontrollably. This can be caused if the proto-oncogenes become oncogenes. Therefore I hypothesize that a cancerous cell will inhibit its growth based on the tumor suppressor gene.
DeleteAdding to what Lesley said, telomeres are sequences of DNA. When DNA is replicated during cell division in somatic cells, a short piece of RNA—called “primer”—helps it get started. Once a primer attaches itself to a DNA strand, DNA synthesis occurs. However, in the beginning, the primer does not attach itself to the very end of the parent DNA strand; therefore, the new copy is missing a section of DNA. Each time a cell goes through cell division, the copied DNA loses more of the end section also called telomeres. Telomeres help protect the DNA strand from getting shorter, and they also “protect chromosomes against degradation, fusion, and rearrangements during DNA replication” (“The importance of telomeres”). Just like the HeLa cells are able to construct the telomere ends again and again, egg and sperm also have the enzyme called telomerase, thus making them “immortal” (“Are Telomeres The Key To Aging And Cancer?”).
ReplyDeleteAre Telomeres The Key To Aging And Cancer? (n.d.). Retrieved January 18, 2015, from http://learn.genetics.utah.edu/content/chromosomes/telomeres/
The importance of telomeres. (n.d.). Retrieved January 18, 2015, from http://www.lifelength.com/importance-of-telomeres.html
Hela cells can be used to in cancer research, biological experiments or cell culture. But why this can be able to live beyond the Hayflick limit, which is the deadline for cell deat(apoptosis), scientists can not be so sure about that.
ReplyDelete