Question

Explain why telomeres are important by using all of the terms below:

-Linear replication

-DNA polymerase

-Okazaki fragment

-Chromosome

Answer 1

Linear replication of DNA or copying a cell’s DNA is semiconservative i.e. one DNA strand is required as a template for the formation of a complementary, new strand. Different enzymes and proteins work together to make the DNA replication process smooth, error free and accurate. DNA polymerases are key molecules for DNA synthesis; they add complementary nucleotides one by one to the 3’ end of the growing chain of DNA. At the replication fork, one of the new strands is made continuously called the leading strand and other strand if formed in small pieces called Okazaki fragments called as lagging strand. These fragments later connect to each other to form an unbroken strand. When the replication fork reaches the end of the chromosome, a part of DNA at the end doesn’t get covered by Okazaki fragment thus, leaving a single-stranded overhang. So during multiple rounds of DNA replication, chromosomes get shorter. The ends of linear chromosomes have DNA caps called telomeres that protect genes to be deleted as cells divide. Telomeres consists of repeated (100-1000 times) six base pair sequence TTAGGG. These single-stranded overhangs form protective loops thus preventing chromosome degradation.