Excision Repair Research Paper

e excision repair is a DNA repair pathway that can repair the damage caused by large changes in the structure of the DNA. In this repair, DNA damage is recognized and the entire affected region (base, sugar, and phosphate) are removed. The complete mechanism is as follows: first a large multienzyme complex scans the DNA for any damage (in the form of distortion/lesion in the double helix). Once the abnormality in the DNA is found, the multienzyme complex cleaves the phosphate backbone on both sides and completely removes the entire nucleotide. The resulting gap in the DNA strand is then repaired by DNA polymerase and DNA ligase.
Translesion synthesis occurs when the damage to the DNA is too severe and regular repair mechanisms (such as
nucleotide …show more content…
However, the multiezyme complex in nucleotide excision repair is much more accurate than the translesion polymerase. The inaccuracy of the translesion synthesis is a major reason why it is only used as a last resort in DNA repair.
Resources:
BIO 687 Textbook: Molecular Biology of the Cell, 6th Edition, by Bruce Alberts et al.
BIO 687 Lecture 6 Slides
2. Why and how can deletions of CTCF binding sites lead to changes in gene expression?
It is believed that a primary role of CTCF is to regulate the 3D structure of chromatin. These CTCF binding sites, along with cohesion ring complex effectively create a loop (chromosome territory) in the chromatin structure. Therefore the CTCF and cohesion ring complex could not create the chromosome territory if one of the CTCF binding sites were to be deleted; the 3D structure of the chromatin would change accordingly. These changes in 3D chromatin structure can effectively alter the portion of the genome that is accessible for transcription, in turn altering which genes are expressed. This change in gene expression can be seen more in depth within the chromosome

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