Helicase:
Role: Unwinds the DNA double helix, breaking the hydrogen bonds between the complementary bases to create the replication fork.
Single-Strand Binding Proteins (SSBs):
Role: Bind to the separated single DNA strands to prevent them from re-annealing or forming secondary structures.
Primase:
Role: Synthesizes short RNA primers that provide a starting point for DNA polymerase to begin DNA synthesis.
DNA Polymerase III:
Role: Adds nucleotides to the 3' end of the RNA primer and synthesizes the new DNA strand in the 5' to 3' direction.
DNA Polymerase I:
Role: Removes the RNA primers and replaces them with DNA nucleotides.
DNA Ligase:
Role: Seals the gaps between Okazaki fragments on the lagging strand by forming phosphodiester bonds, creating a continuous DNA strand.
Topoisomerase (e.g., DNA Gyrase):
Role: Relieves the tension and supercoiling in the DNA that occurs as a result of the unwinding by helicase.
Sliding Clamp:
Role: Helps hold DNA polymerase in place as it synthesizes new DNA, ensuring processivity during replication.
RNAse H:
Role: Removes RNA primers from the lagging strand.
RNA Polymerase:
Role: Catalyzes the synthesis of RNA from a DNA template by adding ribonucleotides to the growing RNA strand in the 5' to 3' direction.
Helicase (transcription):
Role: Unwinds the DNA to allow the RNA polymerase to access the template strand.
Topoisomerase:
Role: Prevents supercoiling of DNA during transcription, similar to its function in replication.
Transcription Factors:
Role: Proteins that bind to specific DNA sequences to facilitate the binding of RNA polymerase to the promoter and the initiation of transcription.