CRISPR is a new technique in genetic engineering that allows scientists to make precise changes in the genetic code. This method is known as gene editing, and it works a bit like how you would edit words on a word-processing program. CRISPR is the technology that makes accurate, easy gene editing possible.
CRISPR is an essential topic for students looking to take molecular biology and related degrees as it is a commonly used technology in genetic engineering. But students learning about CRISPR for the first time might find the lessons daunting. Thankfully, there are many ways to make it more engaging and approachable. Read on to find out how.
First, let’s look at why students find it challenging to learn genetic transfer in bacteria. Here are the top three reasons experienced by both students and teachers.
CRISPR technology involves genes and enzymes, which are extremely small biological molecules. They cannot be seen even through a microscope, so it is much harder for students to appreciate this topic. Understanding how CRISPR gene editing works will be a huge challenge if students cannot see the actual molecules in action.
CRISPR gene editing involves complex genetic mechanisms that may be intimidating to learn for many students. CRISPR is a specific sequence of genetic code that guides an enzyme called Cas9 to its target. Hence, the full name of the system is CRISPR-Cas9. After Cas9 has cut its target, DNA repair mechanisms take over to fill in the gap. These repair mechanisms are similarly complicated, making the topic even more daunting for students.
Simplified mechanism of action of CRISPR-Cas9 gene editing (Image source: Wikimedia Commons.
This topic is full of complex acronyms, such as:
CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats
Cas9: CRISPR-associated protein 9
DSB: Double Strand Break
NHEJ: Non-Homologous End Joining
HDR: Homology Directed Repair
tracrRNA: trans-activating CRISPR RNA
crRNA: CRISPR RNA
These and other related acronyms frequently occur in lessons about CRISPR technology. Textbooks, journal articles, and other academic work often refer to these acronyms, which can make reading necessary material excessively complicated for students who are not acquainted with these acronyms.
Based on students' difficulties studying CRISPR, here are five tips for educators to make the topic more interesting. Each piece of advice addresses a particular challenge that students face.
CRISPR-Cas9 gene editing by itself can seem out of reach for many students. But if you talk about how it can help people, students will easily warm up and open their minds to this topic. Here are some applications of CRISPR technology that are closer to home:
CRISPR-Cas9 gene editing can be used to treat previously incurable conditions like sickle cell disease. In 2019, the first trial of using CRISPR-Cas9 gene editing to restore the normal version of the hemoglobin gene found success. The procedure was able to restore the fetal version of hemoglobin, which is the correct version.
Another application is cancer therapy. CRISPR technology can be used to create a special kind of immune cell called a CAR (Chimeric Antigen Receptor) T cell. CRISPR-Cas9 can modify receptors on T cells extracted from cancer patients, making them more easily target cancerous cells. The modified T cells are then injected into the cancer patient.
Some research has also shown that CRISPR-Cas9 gene editing gives very promising results in treating cancer in children.
Research is still ongoing, but CRISPR technology can soon be a valuable treatment for breast cancer, Huntington’s disease, Tay-Sachs disease, cystic fibrosis, and early-onset Alzheimer’s disease.
Students will benefit a lot if they see colored illustrations, diagrams, graphics, and images. CRISPR, Cas9, and related molecules are too small to be seen, so visual representations are needed to make the topic easier to appreciate. Diagrams, in particular, can help students better understand the process of gene editing with CRISPR-Cas9.
Videos also prove useful in teaching this topic. When students can see the process of gene editing unfold in real time, they will further comprehend the topic.
Interactive simulations are even better. They let students manipulate lab instruments and reagents virtually, so it’s as if they’re doing the real thing. If they make mistakes, there is no risk to themselves or others. Once they master the technique in the virtual world, they will be more confident as they perform actual experiments in the real lab. The image below is from Labster’s simulation entitled CRISPR-Cas applied to TGF-beta induced EMT.
Students must first have a good grasp of fundamental ideas to understand how CRISPR-Cas9 works. Here are some of the basics that students need for this topic.
Single Guide RNA
Also known as gRNA or sgRNA, this synthetic RNA sequence has two parts:
Scaffold sequence: standard sequence needed to bind the selected Cas protein.
Spacer sequence: a sequence of ~20 nucleotides defined by the user to target the specific DNA region to modify
PAM stands for Protospacer Adjacent Motif. It is a DNA sequence in the target genome that is recognized by the Cas protein, allowing the ribonucleoprotein complex to start the process of binding the target DNA. The PAM sequence depends not only on the Cas protein used in the experiment, but also on the species the Cas protein is from and the specific variant.
CRISPR associated protein is an enzyme that binds the gRNA and recognizes the PAM sequence. It also modifies the DNA according to the Cas protein function. The selection of the Cas protein depends on the goal of the experiment. The common Cas protein to generate knock-out cells is Cas9, which has endonuclease activity. However, there are other types of Cas proteins that can be used.
Once introduced in the cells, both components are bound in the cell cytoplasm. They form the ribonucleoprotein complex, which is transferred into the cell nucleus via a protein called importin.
Knockout is the process of inactivating an existing gene by replacing it or disrupting it with an artificial piece of DNA. The loss of gene activity often causes changes in the cells' phenotype, which includes appearance and other observable physical and biochemical characteristics.
Knocking out the activity of a gene provides valuable clues about what that gene normally does. Using cell lines from humans or species with high similarity gives researchers information that can be used to better understand how a similar gene may contribute to diseases. Knockout also offers a biological context in which drugs and other therapies can be developed and tested.
Students who have not experienced using the tools of molecular biology may find lab work intimidating at first. For this reason, it’s important to use firsthand experience to build students’ confidence in using standard lab equipment. Common techniques like pipetting, proper handling of reagents, and the like should be taught in a practical manner.
Once students get the hang of the basic lab techniques, actual lab work for CRISPR-Cas9 gene editing will become easier for them. They will be familiar with routine lab methods already.
If actual lab exercises cannot be done, video demos and interactive simulations prove useful. Simulations like those found in Labster can help students have the necessary skills they need before embarking on actual lab work.
Virtual lab simulations are excellent tools for teaching control of microbial growth. Labster is determined to deliver fully interactive advanced laboratory simulations that make use of gamification elements like storytelling and scoring systems while exposing students to an immersive, realistic, 3D environment.
Check out this simulation called CRISPR-Cas applied to TGF-beta induced EMTat Labster. This virtual lab allows students to perform decontamination and antibiotic selection in a safe, computer-generated environment. With this, students will eventually gain the confidence to perform the procedure independently in an actual lab.
The image below is an example of what students can explore in the simulation.
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