Part 1 Climate Change and Corresponding Efforts in China. Many observations in recent 100 years show that the earthâs climate is now. experiencing significant change characterized by global warming. And the trend of. climate change in China is generally consistent with that of global climate change.
Primase synthesizes the RNA primer that is used to start an Okazaki fragment on the lagging strand. DNA polymerase III continues to add nucleotides to the leading strand right at the replication fork. DNA polymerase I (not at the replication fork) replaces the RNA primers with DNA nucleotides. DNA ligase, also not at the replication fork fuses the new nucleotides produced by polymerase I with the adjacent strand. Replication continues until there are two completely seperate DNA strands that are identical.
These replication forks are the actual site of DNA copying. Helix destabilizing proteins bind to the single-stranded regions so the two strands do not rejoin. Enzymes called topoisimerases produce breaks in the DNA and then rejoin them in order to relieve the stress in the helical molecule during replication. As the strands continue to unwind and separate in both directions around the entire DNA molecule, the hydrogen bonding of free DNA nucleotides with those on each parent strand produces new complementary strands.