The CRISPR-Cas9 Gene-Editing System

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In "Gene-editing hack yields pinpoint precision," Heidi Ledford discusses the CRISPR-Cas9 gene-editing system created by David Liu and Alexis Komor, who are chemical biologists at Harvard University in Cambridge, Massachusetts along with the rest of their team. The gene-editing tool allows DNA changes to be permitted and for mutations to be fixed easily after an enzyme latches itself onto a specific location in the genome with the assistance of a guide RNA molecule. After a RNA molecule discovers a DNA sequence that fits the coding of the guide RNA, it proceeds to separate both of the double helix 's strands at the specific site. In response, the cells attempt to heal the broken area by either adding or removing DNA cells know as bases, which …show more content…
The researchers are experiencing difficulty in just altering the affected letter, which is troubling because as David Liu said, a “majority of disease-associated human genetic variants are point mutations” (Ledford, 2016). Point mutations are especially difficult to manipulate because the part of the gene that is mutated cannot just be easily changed and instead forces upon the alteration of an entire strand. Even more troubling is that point mutations are mutations that play an influential part in a single nucleotide of nucleic acid. Usually, point mutations concern one base being substituted for another and through this process, the complementary base in DNA is …show more content…
Point mutations are commonly the result of environmental factors like X-rays, UV radiation or toxic chemicals, which can cause the development of point mutation by interfering with the DNA’s chemical bonding. It is possible that the error is due to DNA replicating “if DNA polymerase does not catch its own error” (“Mutations,” n.d.). There are three types of point mutations, which are substitution, insertion and deletion and each one is the byproduct of the change concerning a single nucleotide base in DNA. Therefore, influencing the proper execution of the process of protein synthesis. The least harmful point mutation is substitution and influences a single triplet and its corresponding amino acid while not affecting the rest of the protein. Substitution mutation can lead to three outcomes, either nonsense, missense, or silent. Nonsense involves the amino acid being coded to be altered to a stop code, which follows up with the termination of the protein. Through nonsense, a useless protein results. With missense, the alteration of the nucleotide causes a different amino acid and essentially, this potentially may have “little effect, or it may greatly change the resulting protein” (“Mutations,” n.d.). The last type of point mutation is silent, which is the least harmful considering it doesn’t cause an effect on the protein that is noticeable.

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