Question

Marina Melixetian and her colleagues suppressed the expression of Geminin protein in human cells by treating the cells with small interfering RNAs (siRNAs) complementary to Geminin messenger RNA. Forty‑eight hours after treatment with siRNA, the Geminin‑depleted cells were enlarged and contained a single giant nucleus. Analysis of DNA content showed that many of these Geminin‑depleted cells were 4n or greater.

Explain these results.

Answer 1

Re-replication is allowed on geminin depleted cells

Step-by-step explanation:

The depletion of the geminin gene by the siRNA leads to re-replication of portions of the genome. This is due to the protein Geminin be responsible to inhibit the replication factor cdt1 and therefore one replication round is allowed in wild type cells at the S phase. Therefore, Geminin-depleted cells will re-replicate their genome causing the enlargement of the nucleus.