Final answer:
Telomerase is the enzyme that maintains the integrity and length of chromosome ends, known as telomeres, by adding complementary bases to the 3' end of the DNA strand.
Step-by-step explanation:
The function at the end of the telomeres to maintain the integrity and length of the ends of the chromosome is performed by telomerase.
Telomerase contains a catalytic part and a built-in RNA template. It attaches to the end of the chromosome, and complementary bases to the RNA template are added on the 3' end of the DNA strand, thereby elongating the telomere. This enzyme is especially active in germ cells and adult stem cells, but is not active in most adult somatic cells, which is why these cells can age as telomeres shorten over time.
For the discovery of telomerase and its action, scientists Elizabeth Blackburn, Carol W. Greider, and Jack W. Szostak received the Nobel Prize for Medicine or Physiology in 2009.