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The replication crisis is frequently discussed in relation to psychology and medicine, where considerable efforts have been undertaken to reinvestigate classic results, to determine whether they are reliable, and if they turn out not to be, the reasons for the failure. [3] [4] Data strongly indicates that other natural and social sciences are ...
Replication stress and its consequences in mitosis. DNA replication stress refers to the state of a cell whose genome is exposed to various stresses. The events that contribute to replication stress occur during DNA replication, and can result in a stalled replication fork. [1] There are many events that contribute to replication stress ...
Slippage occurs through five main stages: In the first step, DNA polymerase encounters the direct repeat during the replication process. The polymerase complex suspends replication and is temporarily released from the template strand. The newly synthesized strand then detaches from the template strand and pairs with another direct repeat upstream.
Nucleotides (bases) are matched to synthesize the new partner strands into two new double helices. In molecular biology, [1] [2] [3] DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. [4] DNA replication occurs in all living organisms acting as the most essential part of ...
Damage to DNA that occurs naturally can result from metabolic or hydrolytic processes. Metabolism releases compounds that damage DNA including reactive oxygen species, reactive nitrogen species, reactive carbonyl species, lipid peroxidation products, and alkylating agents, among others, while hydrolysis cleaves chemical bonds in DNA. [8]
This is known as the end replication problem. [1] The end replication problem is handled in eukaryotic cells by telomere regions and telomerase. Telomeres extend the 3' end of the parental chromosome beyond the 5' end of the daughter strand. This single-stranded DNA structure can act as an origin of replication that recruits telomerase.
As the cell divides, the telomeres on the ends of chromosomes shorten. The Hayflick limit is the limit on cell replication imposed by the shortening of telomeres with each division. This end stage is known as cellular senescence. The Hayflick limit has been found to correlate with the length of the telomeric region at the end of chromosomes.
The permanent cell cycle withdrawal is mainly done by the wearing off of DNA sequences during S Phase, the second stage during a DNA replication progress. [5] Such progress occurs in the end sequences of the whole linear chromosome named telomeres. Telomeres are sequences of repetitive nucleotides which serve no genetic use.