What is the role of the T-loop in telomeres?

The T-loop plays a crucial role in protecting the ends of chromosomes, which are made up of repetitive DNA sequences known as telomeres. In this context, the T-loop is formed by the folding back of the G-rich strand of the telomere onto itself, creating a loop structure. This looping effectively hides the end of the chromosome from being recognized as a break in the DNA, which could trigger cellular mechanisms that might lead to degradation or fusion with other chromosomes.

By providing this protective mechanism, the T-loop helps to maintain genomic stability by preventing the telomeres from being mistakenly recognized by repair machinery in the cell, which would otherwise treat the ends of the chromosomes as damaged sites that need repair. Thus, the T-loop is essential for preserving the integrity of genetic information during cell division and preventing premature cellular aging.