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.
3. Explain the roles of the positive cell cycle regulators compared to the negative regulators. 4. What steps are necessary for Cdk to become fully active? 5. Rb is a negative regulator that blocks the cell cycle at the G 1 checkpoint until the cell achieves a requisite size.