In this section of CRISPR Made Simple, learn how scientists use CRISPR in scientific research.
Key Takeaways
CRISPR can edit DNA, turning genes “on” or “off,” or swapping genes and gene variants. Scientists use CRISPR in basic research to help figure out what different genes and variants do.
CRISPR was discovered by scientists trying to understand how bacteria and viruses interact. They found that CRISPR acts like scissors, cutting DNA to defend bacteria. In the 2010s, scientists realized that DNA scissors would make a great tool for editing DNA! They figured out how to make CRISPR proteins cut DNA at almost any place they wanted.
When a cell’s own DNA is damaged, the cell repairs it. This repair process is when changes can be made. When DNA is broken, sometimes the cell glues the two ends back together. This doesn’t always work perfectly, and sometimes DNA letters get deleted or added, which can make the gene stop working. So, CRISPR can be used to turn genes “off” by making a cut that is repaired in this sloppy way.
Scientists start with a gene that’s turned ON…
And use CRISPR to make a cut in the DNA.
When the cell repairs the DNA, it does it in a sloppy way that turns the gene OFF.
Scientists can also give the cell a piece of repair DNA. The repair DNA is a sequence that the scientists want to add at the location of the CRISPR cut. The cell will copy this sequence over the break, sort of like putting a patch over a hole. Using this trick, scientists can add new sequences or whole new genes into an organism.
Sometimes harmful gene variants cause diseases.
Scientists use CRISPR to make a cut in the DNA. They also give the cell a healthy DNA sequence to use for the repair.
The cell repairs the DNA, creating a healthy gene variant.
Using CRISPR tools to change DNA is called CRISPR-based gene editing — but for short, people usually just call it “CRISPR.” Labs all around the world use CRISPR to edit DNA. And scientists are working on making new and better CRISPR tools all the time.
Why do scientists edit DNA?
Scientists usually do basic or applied research. Basic research answers questions about how the world and living organisms work. Applied research uses that knowledge to solve problems. Applied research often involves making medicines, machines, and tools.
Scientist use CRISPR in their research in a few main ways:
Figuring out what genes do
Studying human, animal, and plant diseases
Creating medicines or treatments
What do genes do?
Scientist can use CRISPR to figure out what a gene does.
What if you had a machine with lots of parts? How would you figure out what each part does?
You can think of an organism as a complicated machine with lots of parts. Each gene is one part. To learn what a gene does, you can turn it on or off and see what happens. Scientists can use CRISPR to turn genes on and off.
How do you figure out what each part of a complex system does?
Another way to learn more about genes and organisms is to copy a gene from one organism and paste that gene into another organism. For example, green iguanas have spikes going down their back, but dragon lizards don’t have any spikes at all! Maybe the answer is in their genes. Scientists can try adding a gene or a group of genes from the green iguana’s DNA to the dragon lizard. If the dragon lizard grows spikes, that means you’ve found the DNA that make spikes grow!
Researchers can use CRISPR to study all kinds of organisms. Right now, researchers are using CRISPR to understand things like:
Gene variants are changes in some of the DNA letters of a gene. For instance, every butterfly has genes that make them grow wings! But gene variants — a few changes in the DNA letters — make those wings big or small, spotted or striped. Humans have variants in genes, too, that can affect almost any trait.
Many variants contribute to the differences we notice on our friends and families, like how tall people are, if they have big or small feet, and whether or not they have freckles. Some variants can also cause diseases, and others can help prevent diseases.
Many scientists are motivated to figure out what causes diseases so eventually treatments can be made. Making a disease treatment takes a lot of basic research! Scientists need to figure out things like:
Is the disease caused by a gene variant?
Are there gene variants that protect people from this disease?
What happens in someone’s body when they are sick?
CRISPR makes it easier to make genetic changes to cells or animals. This makes it possible to figure out if a gene variant causes a disease. CRISPR also makes it much easier to figure out if gene variants protect against a disease. Can you think of how a scientist might do this?
To answer questions about diseases, scientists need to do experiments. But, they can’t just do experiments on living human patients. So, scientists create disease models. A disease model could be cells in a petri dish. It could also be a whole organism, like a banana plant or a mouse. The cells or organism are made to have some features of the disease.
Animal models are often used to study human diseases.
Plant models are often used to study crop disease.
Creating disease models used to be hard. But CRISPR makes it easier to change DNA. Scientists can use CRISPR to add or remove gene variants in order to create models, better understand diseases, and develop treatments. With CRISPR, scientists can:
Turn a gene on
Turn a gene off
See how having different variants of a gene affects a plant or an animal
Put a gene variant that might cause a human disease into an animal disease model and see what happens
Combine a gene variant that might be protective AND one that is harmful and see what happens
Can you think of more ways scientists can use CRISPR to study genes and disease?
You’ll learn more about using CRISPR in medicine and farming in the next sections!
Summary
CRISPR can be used to edit genes, turning them “on” or “off,” and swapping gene variants. There are two main types of research: basic research, to figure out how the natural world works, and applied research, to make things like machines or medicines. CRISPR can be used in basic or applied research. Scientists use CRISPR in basic research to learn what different genes and gene variants do, create disease models, and study the genetics of diseases.
Think about it!
Have you ever done a science fair project? Was it basic or applied research?
Does basic or applied research seem like more fun to you? Why?
If you could study an organism by turning genes on or off, what organism would you study? What questions would you want to answer? Example: What makes maple trees turn red in the fall?
If you could switch genes/traits between two organisms, what would you switch?
Hope Henderson holds a B.A. in Biology from Brown University and a Ph.D. in Molecular & Cell Biology from the University of California, Berkeley. She joined the IGI in 2019 to work in science communication. In addition to serving as IGI’s main writer, she plans content strategy and manages IGI’s social media, illustration, and translation.
Illustrator
Philippa Steinberg
Philippa Steinberg grew up in Hamburg, Germany. She found her passion for drawing in her early teens and began to self-teach, inspired by an online art community. Now she is an undergraduate studying integrative biology at the University of California, Berkeley. Her goal is to make science more accessible through art.
Key Takeaways
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