The UK's most valuable monument is deemed to be the 1,000-year-old Tower of London, which is worth an estimated Â£56billion to the British economy and came it at number five in the list of European list. Its value is six times more than its nearest rival the Colosseum in Rome, which is valued at Â£72billion.
Cell cycle checkpoints are control mechanisms in eukaryotic cells which ensure proper division of the cell.
G2 checkpoint ensures all of the chromosomes have been replicated and that the replicated DNA is not damaged. restriction point (G1 checkpoint) a point in the animal cell cycle at which the cell becomes committed to the cell cycle, which is determined by external factors and signals.