During our investigation of the DNA/Protein Synthesis unit, we learnt about CRISPR-Cas9, which we explored through the HHMI BioInteractive and the paper model demonstration.

The DNA editing system CRISPR-Cas9 includes two main parts. One of the parts of CRISPR-Cas9 is Cas-9, which stands for CRISPR associated protein 9. The other part CRISPR, stands for clustered regularly interspaced short palindromic repeats. This method, nucleotides in the gene can be added, removed, or changed to edit DNA. Bacterial defense mechanisms use repeated DNA sequences called CRISPR. An enzyme called Cas-9 is created, and it attaches itself to DNA to cut it.

The Cas-9 Guide RNA complex searches for a DNA triplet known as PAM (protospacer adjacent motif) in order to target a certain gene. The guide RNA directs the Cas-9 to the exact place by matching the nucleotide sequence in the target gene.

This is the Cas-9 molecule with its guide RNA:

Cas9 is a DNA-cutting protein with a guide RNA that can identify the DNA sequence that has to be changed. If the RNA is a match, Cas-9 can complementary base pair with it because it unwinds the 5′ side of the DNA in relation to the PAM when it attaches to the PAM.

When RNA aligns with DNA:

Three nucleotides to the 5′ end of the PAM, the RNA and DNA create a double helix. The Cas9 complex unwinds a portion of the DNA after identifying and attaching to the PAM sequence. Cas9 will cut the DNA if the guide RNA and the target sequence match correctly.

The cleaved DNA molecule:

While a mutation will occur between the target DNA and the PAM, the enzymes that started out in the cell will attempt to repair the DNA split.

Two kinds of repairs are possible during the process of CRISPR:

One is known as NHEJ, or non-homologous end joining. The gene will most likely become inactive due to a random mutation that occurs when broken ends are not joined together using a template.

The other method is known as homology-directed repair (HDR), which uses a template for repairing the gene by either replacing a mutation with a non-mutated sequence or adding additional repair templates that the cell will use to heal the DNA break.

Conclusion/Analysis:

We can benefit from CRISPR-Cas9 in a lot of different ways, particularly in the areas of science and medicine. Because of its ability to modify DNA with extreme accuracy, scientists can correct gene errors that lead to illnesses. This technique can improve cancer research models and improve the treatment of genetic problems. Further, it supports farmers in producing more resilient crops that can endure severe weather and insects. With everything looked at, CRISPR-Cas9 offers great potential for future advancements.

Throughout this investigation, we recreated and explained the CRISPR process using a digital simulation alongside a paper copy. The two models that were used effectively represented the pieces and the important steps of the procedure. The investigation’s paper portion gave us a more practical and interactive means of describing how the nucleotides are put into the DNA to change the sequence. The paper model was unable to provide us with a 3-dimensional view that more accurately showed us the locations of each structure, but the online simulation was able to provide us with a more thorough explanation of the unwinding process of DNA as well as a better explanation of the CRISPR overall procedure. I think adding more information about how things change and exploring the complex aspects of the system could improve both models even more. I believe that using a more straightforward model that communicates the main idea in addition to other models that go further into certain aspects and procedures would improve the process’s general understanding. In the end, I think both models effectively clarified the nature of CRISPR and its components.

This is a video that helps explain the concept of CRISPR: