What enzyme is responsible for lengthening telomeres?

Telomerase is the enzyme responsible for lengthening telomeres, which are repetitive nucleotide sequences located at the ends of chromosomes. These telomeric sequences protect the chromosome from degradation and prevent the loss of important genetic information during DNA replication.

Telomerase adds specific nucleotide repeats to the ends of chromosomes, effectively counteracting the natural shortening that occurs during cell division. This process is particularly important in stem cells and germ cells, as well as in some cancer cells, which often exhibit increased telomerase activity enabling them to proliferate indefinitely.

In contrast, helicase is involved in unwinding the DNA double helix during replication, DNA ligase functions to join Okazaki fragments on the lagging strand in DNA replication, and RNA polymerase is responsible for synthesizing RNA from a DNA template during transcription. Each of these enzymes has critical roles in DNA replication and transcription but does not contribute to the maintenance or lengthening of telomeres.