Question

What is telomerase? Give one example of where it's activity is good and one were it is bad.

Answer 1

DNA codes for genetick information are located in all of our cells. When our cells multiply from one to two cells,the DNA within must also replicate.Double-stranded DNA is packaged linearly into chromosomes, most of which form the shape of an X.The ends of these chromosomes are secured against degradation by a protective cap at their distant ends called a telomere (think of "tele" meaning "). Picture a telomere as the cap on a marker, placed there to protect the marker from spoiling.

Telomerase,also called terminal transferase. is a ribonucleoprotein that adds a species-dependent telomere repeat sequence to the 3' end of telomeres. A telomere is a region of repetitive sequences at each and of eukaryotic chromosomes is most eukaryotes.

The genetic information, or"genes," is really just a series of bases called Adenine (A), Guanine (g), Cytosine (C), and Thymine (T). A telomere is repeating DNA sequence for example TTAGGG, at the end of the body's chromosomes thetelomere can reach a length of 15,000 base pairs.

Telomeres function by preventing chromosomes from losing base pair sequences at their ends,They also stop chromosomes from fusing to each other. However. each time a cell divides, some of the telomer is lost usually 25-200 base pairs per division. When the telomere becomes too short, the chromosome reaches a "critical length" and can no longer replicate. This means that a cell becomes "old" and dies by a process called apoptosis. Telomere activity is controlled by two mechanisms, erosion and addition. Erosion, as mentioned, occurs each time a cell divides. Addition is determined by the activity of telomerase.

Telomere integrity is critical for proliferation and survival of cells. telomere dysfunction often resulting from telomere attrition,causes genomic instability leading to cell death of malignant transformation.Telomerase is essential for maintaining telomere lengh and to immortalize cancer cells.While telomere shortening is evident in early stages of porstate cancer 1, the role of telomere dysfunction and telomerase in the development and progression of prostate cancer is largely unkonwn. A recent study from DePinho's laboratory published in the march 2nd issue of cell suggests that whereas telomere dysfunction induced chromosome aberrations that occur in the absence of telomerase are tumorigentic, the manifestation of full malignant phenotype requires telomerase reactivation in prostate cancer-prone mice.