Essay4 Telomerase and Apoptosis
Telomerase and Apoptosis
1. Abstract
Telomerase is one of the factors which delay cell suicide. Telomerase is an enzyme that restores telomeres and increases cell life. Cell suicide, which is delayed by telomerase, may also be caused by other causes. The cause will also be examined in this essay.
2. Intro
Telomerase is a ribonucleoprotein that adds a species dependent telomere repeat sequence to the 3’ end of telomeres. Telomerase is a reverse transcriptase enzyme that carries its own RNA molecule which is used as a template when it used as a template when it elongates telomeres. Telomerase is normally absent or very low levels in most somatic cells.
Telomeres are pieces of DNA that play a role in cell clocks. Enzymes which replicate chromosomes and DNA during cell division can’t continue to replicate to the end of the chromosome. Telomeres protect the end of the chromosome from DNA damage or from fusion with neighboring chromosomes.
3. Result
Telomerase is an enzyme and its main component is protein. However, unlike other enzymes, it contains RNA molecules in addition to proteins. This RNA sequence contains a nucleotide sequence complementary to that of telomere as it acts as a template in elongating the telomeres. Using this structure, telomerase can be extended by adding a telomere sequence to the end of the base sequence of DNA independently of the DNA polymerase.
Cancer cells do not die and proliferate over time because cancer cells have an enzyme called telomerase instead of the telomere. Most of the adult cells have lost telomerase activity. When telomere is shortened, an end-end fusion of chromosomes is observed, which leads to apoptosis. However, when telomere lengths are maintained, the cells continue to divide. In addition, if the cells lose their ability to regulate the cell cycle, the cells will continue to divide.
A telomere is shortened every time cell divides by terminal cloning problems. If this telomere length is shorter than a certain length, it will no longer be capable of protecting the chromosome. This loss of telomere function is recognized by the cell due to DNA damage and progresses to cell senescence or cell suicide.
4. Discussion
Is telomere and telomerase is the only factor for cell senescence and cell suicide?
There is also p53 protein. Cell senescence and cell suicide process through telomere proceeds by p53, which is cancer inhibiting protein. If there is a problem with this protein, it will continue to divide even if the length of the telomere is short.
Cell suicide is also called apoptosis. The cause of apoptosis is divided into two cases, inside and outside depending on the location of the inducing factors. Inside one is cytochrome c of mitochondria. Cytochrome c is an enzyme involved in oxidative phosphorylation and is present in the mitochondrial inner membrane. Apoptosis induced by this is often caused by viruses.
Apoptosis is also important for the immune response to pathogens. CTL recognizes infected cells and releases the enzyme perforin and granzyme. Perforin makes holes in the infected cells, and granzyme penetrates through the holes to activate caspases in the cells. This process is the first step to killing infected cells and replace them with normal cells.
5. Reference
Wikipedia; Telomerase; https://en.wikipedia.org/wiki/Telomerase
Wikipedia; Telomere; https://en.wikipedia.org/wiki/Telomere
Wikipedia; 텔로머레이스; https://ko.wikipedia.org/wiki/%ED%85%94%EB%A1%9C%EB%A8%B8%EB%A0%88%EC%9D%B4%EC%8A%A4
Wikipedia; 세포자살; https://ko.wikipedia.org/wiki/%EC%84%B8%ED%8F%AC%EC%9E%90%EC%82%B4