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Eukaryotes initiate DNA replication at multiple points in the chromosome, so replication forks meet and terminate at many points in the chromosome. Because eukaryotes have linear chromosomes, DNA replication is unable to reach the very end of the chromosomes. Due to this problem, DNA is lost in each replication cycle from the end of the chromosome.
Their repeated nature allows a unique form of mutation: the number of copies can increase or decrease when strand slippage occurs during DNA replication. (Regular point mutation still happens and could be more frequent than slippage.) [7] Their copy number not only have use in forensics and ancestry testing, [8] but are also linked to diseases. [9]
Tandem repeats can occur through different mechanisms. For example, slipped strand mispairing, (also known as replication slippage), is a mutation process which occurs during DNA replication. It involves denaturation and displacement of the DNA strands, resulting in mispairing of the complementary bases.
The presence of repeated sequence DNA makes it easier for areas of homology to align, thereby controlling when and where recombination occurs. In addition to playing an important role in recombination, tandem repeats also play important structural roles in the genome. For example, telomeres are composed mainly of tandem TTAGGG repeats. [15]
Slipped strand mispairing (SSM, also known as replication slippage) is a mutation process which occurs during DNA replication. It involves denaturation and displacement of the DNA strands, resulting in mispairing of the complementary bases. Slipped strand mispairing is one explanation for the origin and evolution of repetitive DNA sequences. [1]
Mutations can be attributed to many factors and come in numerous different forms, however they can mostly be attributed to mistakes that occur during DNA replication or exposure to external factors. [4] As cellular processes are highly efficient, they are not perfect causing disparities between organisms of the same species. [4]
A key feature of the DNA replication mechanism in eukaryotes is that it is designed to replicate relatively large genomes rapidly and with high fidelity. Replication is initiated at multiple origins of replication on multiple chromosomes simultaneously so that the duration of S phase is not limited by the total amount of DNA . [ 1 ]
During DNA replication, the replisome will unwind the parental duplex DNA into a two single-stranded DNA template replication fork in a 5' to 3' direction. The leading strand is the template strand that is being replicated in the same direction as the movement of the replication fork.