Untitled Quiz

Study Notes

Initiation occurs at a single origin of replication, forming a replication "bubble" as DNA strands separate.
A replication fork is created, resembling a Y-shape, where elongation of DNA strands happens.

Helicase: Unzips the DNA helix by breaking hydrogen bonds between nitrogenous bases.
DNA polymerase III: Primary enzyme responsible for adding nucleotides in the 5' to 3' direction during replication.
DNA polymerase I: Replaces RNA primers with newly synthesized DNA segments after initial replication.
Primase: Synthesizes RNA primers that provide a starting point for DNA synthesis.
Ligase: Seals gaps between Okazaki fragments on the lagging strand, forming a continuous DNA molecule.
Topoisomerase: Alleviates tension in the DNA helix by creating temporary breaks before resealing the strands.
Single-strand binding proteins (SSB): Attach to exposed single-stranded DNA to prevent it from rejoining.

Leading strand: Synthesized continuously toward the replication fork in the 5' to 3' direction.
Lagging strand: Discontinuously synthesized away from the replication fork in 3' to 5' direction, creating Okazaki fragments.

Short DNA segments synthesized on the lagging strand; necessary due to the nature of DNA's antiparallel structure.

DNA unwinds at the origin, helicase separates strands, and SSBs prevent rewinding.
Topoisomerase prevents supercoiling ahead of the replication fork.
Primase lays down RNA primers, allowing DNA polymerase to start adding nucleotides.
Following elongation, RNA primers are removed, gaps are filled with DNA, and ligase seals the fragments.