In animal cloning, donor somatic cells should be in which stage of cell cycle?
In animal cloning, donor somatic cells should be in which stage of cell cycle?
Select an option to attempt
Correct Answer: Option C
Explanation
Donor cell stage for SCNT: G0 (quiescent):In somatic cell nuclear transfer (SCNT/animal cloning), the donor somatic cell's cell cycle stage is CRITICAL:• Optimal stage: G0 (quiescent, serum-starved state) or early G1.• Why G0?- G0 nucleus is in a quiescent state with decondensed chromatin.- Compatible with the oocyte's MPF (M-phase Promoting Factor / CDK1-Cyclin B) environment.- MPF causes nuclear envelope breakdown and chromatin condensation.- G0/G1 cells respond optimally to oocyte reprogramming factors.- Chromosomes are fully replicated only once (avoid re-replication problems).• How to achieve G0: Serum starvation for 2–5 days → cells exit cycle and enter quiescence.Landmark: Dolly the sheep (1996) was cloned from a G0-synchronised mammary gland epithelial cell.Note: G2 cells have already duplicated their DNA; S-phase cells are in replication — both are problematic for nuclear transfer.Answer: Donor somatic cells should be in G0 (quiescent) stage before nuclear transfer for optimal reprogramming.