Telomerase and the End-Replication Problem

Abstract

Telomerase and the End-Replication Problem

In eukaryotic cells multiple linear chromosomes must be replicated to accommodate cell division. The double stranded DNA of the chromosomes is separated and two sets of enzyme complexes moving in opposite directions replicate the separated DNA in a semi-conservative manner. Due to the unidirectional nature of these enzyme complexes, the cell is deficient in the ability to completely replicate the chromosome ends. This end-replication problem limits the proliferative capacity of cells. Telomerase is an enzyme complex that creates repetitive DNA sequences (in complex with proteins) that protect chromosomes from the degradation associated with the end-replication problem. Through this activity, Undergraduate students learn to describe why the unidirectional nature of DNA polymerase leads to the end replication problem on the lagging strand during synthesis.  They will also learn to Explain the role of telomerase in preventing chromosome erosion following successive mitotic divisions. Last, upon completion of this POGIL learning cycle activity, students should be able to Identify the role of telomerase in cell immortalization/tumorigenesis. This is a POGIL activity designed for implementation in an introductory biology course. Standard lecture halls or classrooms that can accommodate up to 60 students should work well.

Level: Undergraduate
Environment: Classroom
Activity Type: Learning Cycle
Discipline: Biology
Course: Introductory Biology
Keywords: cell division, cell immortalization, chromosome, DNA, eukaryote, mitosis, telomerase, replication, tumerogenesis