Telomeres are non-coding regions at the end of the DNA sequence. Because some end segments are lost in DNA replication, the telomere allows necessary sections of protein coding DNA to remain unharmed during multiple cell division cycles.
At the end of the chromosome, there is a section of DNA that does not get covered by an Okazaki fragment because the primer would fall beyond the chromosome's end. As a result, the ending sequences cannot be covered by an Okazaki fragment and does not get replaced by DNA (gets cut off).
Telomeres are single stranded overhangs at the end of the DNA sequence. However, a complementary strand is formed in DNA, creating a protective loop that protects telomeres from the DNA repair system.
Telomerase is a specialized DNA polymerase that uses an RNA template for DNA creation. First, telomerase binds to the RNA molecule that contains the sequence for the telomere (TTAGGG). Then it adds nucleotides to the overhanging strand, lengthening the telomere. After the strand is long enough, an RNA primer and DNA polymerase will create the other strand to produce double stranded DNA.
Germ cells need to provide all the necessary protein coding DNA as well as enough telomere to give rise to an offspring with a normal lifespan. If telomerase was not active in germ cells, then each generation would have a shorter lifespan than the previous.