Question

What lead to expansion of D loop?

Answer 1

D loop:

1. D loop is a DNA structure where the two strands of a double-stranded DNA molecule are separated for a stretched and held apart by third strand of DNA.
2. In some of the strands which are designated as crossovers, a different sequence of events occurs.
3. The first detectable step of these series of events is the sequence is the stabilization, by unknown means ,of interaction between the invading single-strand and its homolog—resulting in a structure called a single-end invasion.
4. The extension of the single strand then leads to expansion of the D-loop, interacting with the second single-stranded end generated at the original double-strand break.
5. Further DNA synthesis and ligation fill in the gaps, and the final result is a DNA structure called a double Holliday junction.
6. A specific pair of DNA cleavage reactions, followed by DNA repair, transform this structure into a crossover.