BIOL3108 Lecture Notes - Lecture 17: Terf2, Telomere, Telomerase
Document Summary
Lectures 10-12 will not be examined (thomas" lectures) Barbara mcclintock identified telomeres: specialised structures at the ends of corn chromosomes protecting them from end-to-end fusions. This work, and the demonstration of movable genetic elements in the genome (transposons) earned mcclintock the nobel prize in 1983. Every chromosome carries telomeres at both ends and the telomerase enzyme is required to prevent end-to-end fusion. Telomeres detected by fluorescence in situ hybridization (fish) dna probes to repeated sequences in telomeric dna (yellow dots) in human cells in metaphase (dna purple) prior to separation of paired chromatids in mitosis. Cells deprived of telomeric repeat-binding factor 2 (trf2), a protein that maintains normal telomere structure, undergo end-to-end fusions to generate one massive chromosome! Chromosome end joining -> giant mass of chromosome, where the ends can no longer be recognised -> these cells die. Telomeric dna progressively shortens following each growth- and cell division cycle until the telomeres are too short to protect chromosome ends.
