End to end genome sequencing

Context: On May 27, a preprint titled “The complete sequence of the human genome” was posted in the online repository bioRxiv.

Researchers at the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health (NIH), have produced the first end-to-end DNA sequence of a human chromosome.
The effort is part of a broader initiative by the Telomere-to-Telomere (T2T) consortium, partially funded by NHGRI. The consortium aims to generate a complete reference sequence of the human genome.
The T2T consortium is continuing its efforts with the remaining human chromosomes, aiming to generate a complete human genome sequence in 2020.
They have, in the process, discovered over a hundred new genes that code for proteins. The total size of the genome they have sequenced is close to 3.05 billion base pairs.
In this study, researchers did not sequence the X chromosome from a normal human cell. Instead, they used a special cell type — one that has two identical X chromosomes. Such a cell provides more DNA for sequencing than a male cell, which has only a single copy of an X chromosome. It also avoids sequence differences encountered when analyzing two X chromosomes of a typical female cell.

Significance:

The Human genome project announced in 1990 announced a complete human genome but about 15% of it was incomplete. Due to limitations of technology scientists were not able to piece together some of the repetitive parts of the human genome.
This study adds 200 million base pairs to the last draft of the human genome that was published in 2013. The results come with the caveat that about 0.3% may still have errors, and that among the sex chromosomes, only the X chromosome has been sequenced.

Concept:

What is special about protein-coding genes?

There are long stretches that do not seem to have a particular function. On the other hand, protein-coding sequences or protein-coding genes are DNA sequences that get transcribed on ribonucleic acid (RNA) as an intermediate step.
These in turn make the proteins responsible for various functions such as keeping the body healthy or determining the colour of the eye — proteins carry out the instructions encoded in the genes.

Genome Sequencing:

Genome Sequencing means deciphering the exact order of base pairs in an individual.

In this particular piece of DNA, an adenine (A) is followed by a guanine (G), which is followed by a thymine (T), which in turn is followed by a cytosine (C), another cytosine (C), and so on.

Whole/End to end Genome Sequencing:

Whole-genome sequencing involves breaking the genome up into small pieces, sequencing the pieces, & reassembling the pieces into the full genome sequence.
To know which genes of a person’s DNA are “mutated” the whole genome sequencing is required.
Whole genome sequencing is the process of determining the complete DNA sequence of an organism’s genome at a single time.
Because a human genome is incredibly long, consisting of about 6 billion bases, DNA sequencing machines cannot read all the bases at once. Instead, researchers chop the genome into smaller pieces, then analyze each piece to yield sequences of a few hundred bases at a time. Those shorter DNA sequences must then be put back together.

Advantages of End to end Genome Sequencing:

The ability to generate truly complete sequences of chromosomes and genomes is a technical feat that will help us gain a comprehensive understanding of genome function and inform the use of genomic information in medical care.