The initiation of DNA replication in eukaryotes is basically similar to that in prokaryotes

Eukaryotic DNA is distributed on many chromosomes and replicated individually. There are thousands of replicators on each chromosome, and there are many starting points for replication.

Replication is sequential, and highly repetitive sequences (such as satellite DNA, centrosomes, and telomeres) are replicated in the final stage of S phase.

Eukaryotic replication initiation is also the process of opening double strands to form replication forks, forming primers and synthesizing RNA primers.

Elongation of eukaryotic DNA replication occurs through conversion of DNA polymerase

DNApolα mainly catalyzes the synthesis of primers, and is quickly replaced by DNApolδ and DNApolε, which have continuous synthesis capabilities. This process is called polymerase switching.

1. Telomeres are structures at the ends of linear DNA molecules in eukaryotic chromosomes. It is formed by the tight combination of DNA and its binding proteins, and looks like two "caps" covering both ends of the chromosome. Its composition is characterized by multiple repetitions of short sequences rich in G and T bases. Telomeres play an important role in maintaining the stability of chromosomes and the integrity of DNA replication. It has been found that when genetic mutations form tumors, telomeres can appear as deletions, fusions, or sequence shortening.

2. Telomerase is an enzyme composed of RNA and protein. It is a special reverse transcriptase. RNA and protein are essential components for enzyme activity. Telomerase uses its own RNA as a template to catalyze the synthesis of telomere DNA fragments to prevent chromosome shortening. Telomerase is composed of three parts: telomerase RNA, telomerase cooperating protein 1 and telomerase reverse transcriptase. This enzyme has the functions of providing RNA template and catalyzing reverse transcription.

3. When replication is terminated, telomerase maintains the integrity of the chromosome through a mechanism called the crawling model.

1. An important feature of eukaryotic chromosome DNA replication is that replication only occurs in the S phase of the cell cycle and can only be replicated once.

2. The initiation of DNA replication in eukaryotic cells occurs in two steps, namely the selection of replicating genes and the activation of replication origins. These two steps occur at specific stages of the cell cycle.

3. Activation of replication origins coincides with cell cycle progression.

1. D-loop replication is the replication method of mitochondrial DNA. Primers need to be synthesized during replication.

2.mtDNA has a closed circular double-stranded structure, and the first primer uses the inner loop as a template to extend. When reaching the second origin of replication, another reverse primer is synthesized and the outer loop is used as a template for reverse extension. Finally, the replication of two double-stranded circular DNAs is completed.