In class, we have been learning about the biotechnology tool called CRISPR-Cas9. This accessible tool is used to alter the DNA within a variety of cells and organisms. To understand CRISPR-Cas9, we worked with paper models to demonstrate how this form of biotechnology operates and alters DNA mutations.
The CRISPR-Cas9 is a type of gene editing technology that can remove and input different DNA sequences to enhance genes. CRISPR stands for “Clustered Regularly Interspaced Short Palindromic Repeats” and Cas9 is the enzyme. The enzyme is scissor-like and is responsible for severing the DNA to make way for the new sequence. The RNA component, guide RNA, is designed to bring the enzyme to the target DNA sequence.
Each CRISPR-Cas9 is programmed to seek out a specific three-nucleotide DNA sequence called PAM (protospacer adjacent motif). When it bonds to the sequence through complementary base pairing, CRISPR-Cas9 unwinds the DNA. In order for the CRISPR-Cas9 to cleave DNA, it first bonds with its respective RNA pair. Once this occurs, the Cas9 nuclease is activated, initiating the precise cut that is made to both strands of the DNA double helix.
CRISPR-Cas9 can repair defective DNA via a “knockout”. This can be done in two different ways. The first is done by nonhomologous end joining or NHEJ, which is a repair mechanism. When correctly used, it can send the Cas9 into a repeating cycle of cleaving and repairing. Unfortunately, this can eventually cause a mutation in the gene. CRISPR-Cas9 will then “knock out” the mutated gene. The second way that CRISPR-Cas9 can repair DNA mutation is through homology-directed repair (HDR). The HDR is used as a template that the CRISPR-Cas9 uses to repair mutations. This strategy is less error-prone than the NHEJ, as the CRISPR-Cas9 is using a template to achieve the repair.
The CRISPR-Cas9 can be used to benefit us in many different fields, such as agriculture and medicine. There are also benefits in the cost-effectiveness of biotechnology, as CRISPR-Cas9 is more affordable and more precise than others like it in the past. CRISPR-Cas9 can be used in agriculture to create food that is more pest-resistant. It can also be used in the world of medicine to create more personalized cancer treatment.
The paper CRISPR-Cas9 model accurately showed the process of said biotechnology. It was able to simplify the process for us to see the basic steps and get surface-level knowledge of CRISPR-Cas9. Unfortunately, the model lacked the ability to show more detail and did not show the unzipping and unwinding steps involved at all. Improving this portion of the activity could be done by having students cut the double helix to showcase the unwinding and unzipping that CRISPR-Cas9 does.
This was an effective way to show students the basic level of knowledge of the CRISPR-Cas9. It gave us the ability to do the process with our hands and visually see what was going on throughout. It was a good way to get basic information and building from the activity was easier because of the background knowledge this activity gave us.
Works Cited:
https://medlineplus.gov/genetics/understanding/genomicresearch/genomeediting/
https://www.yourgenome.org/facts/what-is-crispr-cas9/
https://www.idtdna.com/pages/research-area/clinical-diagnostics/crispr