How is 3 overhang strand of telomeres lengthened in eukaryot

How is 3’ overhang strand of telomeres lengthened in eukaryotes? . In your answer, i) nucleotide sequences of RNA of telomerase AND initial 3’ overhang DNA must be stated. ii) nucleotide sequences being added at the end of 3’ overhang DNA during each of the two elongation steps must be stated. Explain.

-I need a detailed and conceptual explaination with minimal images.

Solution

Telomeres of linear eukaryotic chromosomes have many tandem copies of a short oligonucleotide sequence. It has guanine residues in one strand and cytosine in the complementary strand. Since the G rich strand is longer, it leaves a region of single-stranded DNA of few hundred nucleotides at the 3’ end. This 3’ overhang serves as primer for telemere’s elongation by telomerase enzyme. The enzyme telomerase contains both RNA and protein components. The RNA component is150 nucleotides long and there are around 1.5 copies of the appropriate CyAx telomere repeat. These CyAx sequences serve as a template for synthesis of the TxGy strand of the telomere of linear DNA.