Question

What cell cycle phase should the cells be in to be perfect of Homology Directed Repair in the moss Physcomitrella patens? And in which article is it stated?

Answer 1

The Cell Cycle is a 4-stage process consisting of Gap 1 (G1), Synthesis, Gap 2 (G2) and Mitosis. An active eukaryotic cell will undergo these steps as it grows and divides. After completing the cycle, the cell either starts the process again from G1 or exits the cycle through G0. From G0, the cell can undergo terminal differentiation.

G1 phase

• Cell increases in size
• Cellular contents duplicated

S phase

• DNA replication
• Each of the 46 chromosomes (23 pairs) is replicated by the cell

G2 phase

• Cell prepares for cell division

M phase

• Mitosis followed by Cytokinesis (cell separation)
• Formation of two identical daughter cells

HDR is a faithful repair pathway. It comes into action mainly in the S- or G2-phase of the cell cycle and requires homologous DNA sequences. Homologous recombination is the desired mechanism for precise genome editing, which only happens in the presence of a homologous duplex template to repair the broken site.