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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.
For example, if the 100th base of a nucleotide sequence mutated from G to C, then it would be written as g.100G>C if the mutation occurred in genomic DNA, m.100G>C if the mutation occurred in mitochondrial DNA, or r.100g>c if the mutation occurred in RNA. Note that, for mutations in RNA, the nucleotide code is written in lower case.
At some point during the replication process, the polymerase dissociates from the DNA and replication stalls. When the polymerase reattaches to the DNA strand, it aligns the replicating strand to an incorrect position and incidentally copies the same section more than once. Replication slippage is also often facilitated by repetitive sequences ...
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.
Triplet expansion is caused by slippage during DNA replication, also known as "copy choice" DNA replication. [2] Due to the repetitive nature of the DNA sequence in these regions, 'loop out' structures may form during DNA replication while maintaining complementary base pairing between the parent strand and daughter strand being synthesized.
Recurrent evolution also referred to as repeated [1] [2] or replicated [3] evolution is the repeated evolution of a particular trait, character, or mutation. [4] Most evolution is the result of drift, often interpreted as the random chance of some alleles being passed down to the next generation and others not.
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]
In eukaryotes, the cell cycle consists of four main stages: G 1, during which a cell is metabolically active and continuously grows; S phase, during which DNA replication takes place; G 2, during which cell growth continues and the cell synthesizes various proteins in preparation for division; and the M phase, during which the duplicated ...