Final answer:
DNA replication in eukaryotes has multiple origins and is bidirectional, involving a complex process that ensures efficient replication of the large and complex eukaryotic genome.
Step-by-step explanation:
DNA replication in eukaryotes is characterized by multiple origins of replication and is bidirectional. This means that the replication process starts at many different points within the genome and proceeds in both directions from each point. The human genome itself can have between 30,000 to 50,000 origins of replication. Each origin forms a replication bubble with replication forks at either end. As replication progresses, these forks move away from the origin, allowing for the new strands to be synthesized.
In contrast to eukaryotes, prokaryotes such as E. coli have a single origin of replication. Eukaryotic cells have to replicate much more DNA compared to prokaryotic cells, and having multiple origins is one of the ways eukaryotic cells accomplish this efficiently. The process involves various enzymes and proceeds through stages of initiation, elongation, and termination, much like prokaryotic replication but suited to the complexity and packaging of eukaryotic DNA.
During replication in eukaryotes, special sequences on the chromosomes act as origins of replication where enzymes like helicases begin unwinding the DNA strands. Single-strand binding proteins stabilize the unwound DNA, and RNA primases lay down RNA primers for new strand synthesis. DNA polymerases then add nucleotides in a 5' to 3' direction, creating the leading and lagging strands. Once replication is complete, DNA ligases seal any remaining gaps, ensuring a continuous double-stranded DNA molecule.