NGS overlapping reads

Question

[xd_d]

Hello everyone, I try to understand how became overlap reads with NGS . For example see here:

Question:

In which step in NGS i create this overlap reads. How I get this overlap when I break down one cDNA/DNA.. or is this a multiple step with many cDNA/DNA from the same tissue ? Please Help me

[GenoMax]

See if this animation video helps. When you fragment source DNA that fragmentation gives rise to random (in theory) fragments, which are then sequenced.

Answer 1

[d-cameron]

Your question is somewhat unclear as to what sort of read overlap you are referring:

• Reads from different read pairs overlapping the same reference sequence. These reads originate from different fragments of different copies of the same DNA template. For human, your input library will contain many many copies of chr1 from many different cells. These are copies are randomly fragmented.

• Reads from the same read pair with overlapping alignments. Your pictures show that your fragment lengths are all 200-100bp. If your fragment is less than 200bp, or if you do 2x150bp sequencing of a 200bp fragment, the two reads from the same fragment will overlap since the reads sequencing for either end of the fragment and the fragment is less than twice the read length.

Answer 2

[Petr Ponomarenko]

multiple cells => multiple DNA molecules => cut into pieces almost randomly (say with sonication) => certain sizes of cuts are selected => reads from random location => reads overlap

Probably the most fun way to explain is this https://www.youtube.com/watch?v=-7GK1HXwCtE =) This opens up a topic of fun NGS and bioinformatics videos, I gues