Practice question

Mammalian chromosome ends protected by telomeres composed of tandem hexanucleotide repeats synthesized by telomerase ribonucleoprotein carrying RNA template TERC. In all vertebrates including humans repeat is TTAGGG on G-rich strand oriented 5 prime to 3 prime toward terminus, extending 10 to 15 kilobases at birth with single stranded 3 prime overhang forming T-loop invading duplex repeats. TTAGGG specifically binds shelterin proteins TRF1, TRF2, POT1, TIN2 protecting end from DNA damage response. Other organisms possess variants like TTGGGG in Tetrahymena, but human sequence strictly conserved and detectable by FISH.