Our Basic Building Blocks & How To Change Them
Imagine being able to change the appearance of a child, before they’re even born, and when I say change, I mean lowering the chance of any hereditary illnesses occurring, or even changing the overall appearance, to make them look like the perfect child. Well, what if I told you that eventually, this dream could become a reality? 💭
You’d probably tell me that it’s impossible, or that it’s something straight out of a sci-fi movie, and that’s where you’d be incorrect.
With the recent technological advancements made within gene-editing tools, scientists are working towards being able to change our physical traits, from eye colour to even limiting the chances of being diagnosed with certain diseases! 🤯
Every living thing on this Earth is defined by its genes, and the DNA within these genes acts as an instruction manual for our cells. Think of it like this, humans are like a complex LEGO set, and the DNA within our genes is the neverending instruction manual. 🧱
Within our bodies, the DNA molecule consists of two strands that wrap around one another to form a double helix. 🧬 Each one of these strands is made out of alternating sugar and phosphate groups. Attached to each sugar is one of four bases, also known as building blocks — Adenine (A), cytosine (C), guanine (G), and thymine (T).
The two strands are held together by bonds between the bases; adenine bonds with thymine, and cytosine bonds with guanine. The sequence of the bases along the backbones serves as instructions for assembling protein and RNA molecules. are strung together in precise sequences, and tell the cell how to behave. This forms the base for every single one of our traits, from finger shape to eye colour.
So, where does the part about changing a child’s appearance come into play?
That’s where CRISPR comes into play. CRISPR is one of the most cost-efficient, fastest, and easier gene-editing tools responsible for this wave of gene editing advancements.
CRISPR (an acronym for clustered regularly interspaced short palindromic repeats) is a natural process within our bodies and is used mainly as a bacterial immune system. It can be found defending single-celled bacteria and archaea against invading viruses. 🛡️
Naturally occurring CRISPR uses two main components; short snippets of repetitive DNA sequences (CRISPRs) and CRISPR-associated proteins (Cas). The CRISPR-associated proteins chop up DNA like scissors, but for your molecules. ✂️ For example, when a virus invades a bacterium, Cas proteins cut out a segment of the infected DNA to stitch into the bacterium’s CRISPR region, and this captures a chemical snapshot of the infection. 📸
These snapshots are copied and made into short pieces of RNA, which is essentially the messenger that carries instructions from DNA to the majority of our proteins. It also plays many other roles within our cells. In this case, RNA binds to a special protein called Cas9. After they bind together, the resulting creations act like magnets, and attach onto unbound genetic material, and search for a match to the virus. If the virus invades again, the complex recognizes it instantly, and Cas9 destroys the viral DNA. 🚫
Of course, many bacteria have this defence mechanism. But, in 2012, scientists discovered how to overtake CRISPR to be able to target more than viral DNA in any organism. With precision, the right tools, and technology, it becomes a precise gene-editing tool, which could alter any DNA and change specific genes almost as easily as using white-out (actually, that’s not always easy, maybe more like deleting a typo).
So, how does this work? 🤔
Scientists design a “guide” RNA to match the gene they want to edit and attach it to the Cas9. Similar to the viral RNA in the CRISPR immune system, the guide RNA directs Cas9 to the target gene, and the protein’s molecular scissors snip the DNA. This is the key to CRISPR’s power; By injecting Cas9 and binding it to a short piece of custom RNA, scientists can edit any gene in the genome. ✍️
Once the DNA is cut, the cell will try to repair it. Typically, proteins called nucleases trim the broken ends and join them back together. But this type of repair process, called nonhomologous end joining, often causes mistakes to occur and can lead to extra or missing bases. 🔎 Therefore, the resulting gene is often unusable and shut down. However, if scientists add a separate sequence of template DNA to this process, cellular proteins can perform a different DNA repair process, called homology-directed repair. This template DNA is used as a blueprint to guide the rebuilding process, repairing a defective gene or even inserting a completely new one. The ability to fix DNA errors means that CRISPR could possibly create new treatments for diseases linked to specific genetic errors, like cystic fibrosis. 🦠
And since it’s not limited to humans, the applications are almost endless. CRISPR could create plants that grow larger fruit, extend the shelf life of produce, or even reprogram cancer cells!
It’s also a powerful tool for studying the genome, allowing scientists to watch what happens when genes are turned off or changed within an organism. 🔬 Using CRISPR for these purposes isn’t perfect yet — It doesn’t always make just the intended changes, and since it’s not easy to predict the long-term implications of a CRISPR edit, it raises ethical concerns. It’s up to us to decide the best path to take as CRISPR heads into hospitals, labs, and organisms around the world. 🌎
Additional Readings:
