Telomerases are the enzymes that add additional nucleotides to the ends of the deoxyribonucleic acid (DNA) molecules. During replication, the primers that are added initially in the ends of the lagging strand and the one in the leading strand would leave gap that would shorten the length of the DNA molecule. If this happens then a major portion of the DNA would be lost.
The telomerase during replication adds additional nucleotides at the ends of the DNA molecule, thereby preventing the DNA from being shortened. If any mutation leads to the loss or prevention of production of telomerase, it would lead to the loss of essential information and death. In fact, there are theories stating that absence of telomerases leads to the aging in humans.