Final answer:
The ends of linear chromosomes, known as telomeres, are maintained by the enzyme telomerase, which has a built-in RNA template and extends the 3' end to prevent chromosome shortening.
Step-by-step explanation:
The ends of linear chromosomes are maintained by an enzyme known as telomerase. This enzyme is crucial for solving the end replication problem that occurs because DNA polymerase cannot replicate the extreme 3' ends of chromosomes. Telomerase contains a built-in RNA template which it uses to extend the telomeres, the repetitive DNA sequences at the chromosome ends, and thus prevent the chromosomes from progressively shortening during cell division. In humans, the TTAGGG sequence is repeated hundreds to thousands of times in the telomeres. Elizabeth Blackburn and her colleagues received the Nobel Prize for their discovery of telomerase and its function.
The ends of the linear chromosomes are known as telomeres, which have repetitive sequences that protect the genes from getting deleted as cells continue to divide. The enzyme telomerase helps in maintaining the ends of the chromosomes by adding complementary bases to the RNA template on the 3' end of the DNA strand. Once the lagging strand template is elongated, DNA polymerase adds the nucleotides complementary to the ends of the chromosomes.