The \"end problem\" in eukaryotic DNA replication a. is solved by telomerase b. refers to loss of chromosome ends during replication c. is solved by an RNA dependent DNA polymerase d. A and B e. all of the above Solution Answer : The correct answer is E ( All of the above) Explanation : Telomerases are the ribonucleoprotein complexes containing a small RNA that serves as a template for addition of new six nucleotide repeats. Or Telomerase, the enzyme that synthesizes the telomere ends of linear chromosomes, is a specialized reverse transcriptase that contains an internal RNA template. Telomeres undergo cycles of shortening of the lagging strands due to the inability to complete synthesis. Most normal cells lose telomerase activity with increaseing age of the organism and repeated generations of the cell division. In other words, after certain number of divisions normal cells reaches the Hayflicks limit beyond which cells will no longer devide instead they die. In germ-line cells, which contain telomerase activity, telomere lengths are maintained; for example, telomerase is highly expressed only in cells that need to divide regularly especially in male sperm cells. Whereas somatic cells lack telomerase activity due to which they die after certain number of generations. In cancer cells/tumor cells, end replication problems observed in normal cells will be taken care by the telomerase enzyme which makes the cells to bypass the Hayflick limit and become immortal, thus avoiding cell death Many cancer cells are considered \'immortal\' because telomerase activity supports them to live longer than somatic cells. 90% of the cancer cells retain the ability to express telomerase and acquires the ability to proloferate indefinitely..