Anatomy and Physiology 12 – CRISPR-Cas9 analysis

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OVERVIEW
In Anatomy and Physiology 12, we have been examining DNA and the process of protein synthesis, with a lesson and emphasis on CRISPR-Cas9. CRISPR-Cas9 is a gene editing technology which lets scientists alter DNA accurately by adding, deleting, or substituting genes. This innovative technology is employed in multiple ways, such as: to fix mutations, investigate genetic functions, and enhance health.
WHAT IS CRISPR-CAS9?
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats, while Cas9 is an enzyme that performs as “scissors”, cutting DNA. Together, CRISPR-Cas9 is a gene-editing system that can target and change specific parts of certain genes, for better performance.
ACTIVITIES AND PROCESSES
To understand how this technology works, we performed different activities that further developed on the concept of CRISPR. These activities were: the paper cut out model activity, and multiple online activities. Both of these ways of learning helped to visualize and understand each step of the CRISPR process, from how the enzyme finds a target sequence to how DNA can be cut and repaired. By participating in these not only hands-on but also digital visuals, we developed a clearer understanding of how scientists can “knock out” or “knock in” genes using CRISPR.

Once the CRISPR-Cas9 system is inside of the cell, the guide RNA finds the DNA for a matching sequence. When it finds the right spot, Cas9 searches for a PAM sequence – a short pattern like “GGG,” – and attaches itself there. This is a necessary step, since it ensures the cut/change happens at the correct location to reduce harmful consequences.

After Cas9 has bonded to the DNA at the PAM site, it cuts both sides of the DNA – this cut lets scientists change the DNA in that precise spot.

When DNA is cut, cells will immediately try to repair that change/damage. One method of reparation, is called Non-Homologous End Joining (NHEJ), in which, the cell binds the broken DNA ends together again. However, the cell can also accidentally add random DNA sequences. Because of that, this repair can make small mistakes, turning off a gene.

Another method scientists may use is homology-directed repair (HDR). This process is undergone by giving the cell a piece of “donor DNA” as a template, which they can then guide to repair the DNA accurately or insert new information.

 

BENEFITS AND LIMITATIONS OF MODELS

In the CRISPR modeling activity we did, we used paper cut out models and an online imitation of the process, to see and understand how the process works. These models:

– Allows us to observe the main steps of CRISPR-Cas9, such as the attachment, cutting and repairing of DNA.

– Made it simpler to imagine what happens inside a cell, by giving us first-hand views.

Of course, however, there were limitations to these activities.

– These models did not have life sized explanations, and they didn’t show how CRISPR-Cas9 moves, nor how it wraps around DNA.

– There was also a difficulty in seeing how random DNA pieces were added during repair.

SUGGESTIONS

To make the paper cut out activity better, the models could show the actual size of CRISPR-Cas9,, and clearly show how CRISPR works inside the cell. There could also be benefit in having certain steps where students must figure out the changes, or guess what process the cell would undergo next. These changes/improvements could make the activities more fun, and easier to understand.

IMAGES OF PROCESSES

This image shows the CRISPR-Cas9 enzyme binding to the target DNA with the help of gRNA and the PAM sequence

This image shows the CRISPR-Cas9 acting as scissors, and cutting both strands of DNA (creating a double-strand).

This image shows the cell repairing the cut through NHEJ, often adding random nucleotides which can deactivate or change the gene.

This image shows cell using the donor DNA during HDR to repair (or replace) part of the gene.

CONCLUSION

Models can be a fantastic way to help students understand difficult science topics. They make hard ideas simpler and become more visual, which allows people to see the connection with science to real life. However, models don’t always show every detail, so it’s important for them to be explained clearly. All in all, these activities and models were extremely helpful to use for learning and understanding of CRISPR-Cas9.

 

SOURCES/CITATIONS

Class materials:

– Anatomy and Physiology 12 Textbook

– OneNote information

 

Other sources:

“Gene Editing.” CRISPR Therapeutics, crisprtx.com/gene-editing. Accessed 29 Oct. 2025.

Redman, Melody, et al. “What Is CRISPR/Cas9?” Archives of Disease in Childhood. Education and Practice Edition, U.S. National Library of Medicine, Aug. 2016, pmc.ncbi.nlm.nih.gov/articles/PMC4975809/.

“What Are Genome Editing and CRISPR-Cas9?: Medlineplus Genetics.” MedlinePlus, U.S. National Library of Medicine, medlineplus.gov/genetics/understanding/genomicresearch/genomeediting/. Accessed 29 Oct. 2025.

 

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