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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.
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.
Other effects of point mutations, or single nucleotide polymorphisms in DNA, depend on the location of the mutation within the gene. For example, if the mutation occurs in the region of the gene responsible for coding, the amino acid sequence of the encoded protein may be altered, causing a change in the function, protein localization ...
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]
Occasionally, within a sample of individuals such as in paternity testing casework, a mutation in the DNA flanking the microsatellite can prevent the PCR primer from binding and producing an amplicon (creating a "null allele" in a gel assay), thus only one allele is amplified (from the non-mutated sister chromosome), and the individual may then ...
A postzygotic mutation (or post-zygotic mutation) is a change in an organism's genome that is acquired during its lifespan, instead of being inherited from its parent(s) through fusion of two haploid gametes. Mutations that occur after the zygote has formed can be caused by a variety of sources that fall under two classes: spontaneous mutations ...
When a DNA trinucleotide repeat sequence is damaged, it may be repaired by processes such as homologous recombination, non-homologous end joining, mismatch repair or base excision repair. Each of these processes involves a DNA synthesis step in which strand slippage might occur leading to trinucleotide repeat expansion. [4]