How does the replication machinery know where to begin? It turns out that there are specific nucleotide sequences called origins of replication where replication begins. It is now known that DNA pol III is the enzyme required for DNA synthesis DNA pol I and DNA pol II are primarily required for repair. In prokaryotes, three main types of polymerases are known: DNA pol I, DNA pol II, and DNA pol III. When the bond between the phosphates is broken, the energy released is used to form the phosphodiester bond between the incoming nucleotide and the growing chain. The addition of nucleotides requires energy this energy is obtained from the nucleotides that have three phosphates attached to them, similar to ATP which has three phosphate groups attached. One of the key players is the enzyme DNA polymerase, also known as DNA pol, which adds nucleotides one by one to the growing DNA chain that are complementary to the template strand. The process is quite rapid and occurs without many mistakes.ĭNA replication employs a large number of proteins and enzymes, each of which plays a critical role during the process. This means that approximately 1000 nucleotides are added per second. coli has 4.6 million base pairs in a single circular chromosome and all of it gets replicated in approximately 42 minutes, starting from a single origin of replication and proceeding around the circle in both directions. Discuss the role of different enzymes and proteins in supporting this processĭNA replication has been extremely well studied in prokaryotes primarily because of the small size of the genome and the mutants that are available.Explain the process of DNA replication in prokaryotes.Learning Objectives By the end of this section, you will be able to:
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