The gene-editing technology known as CRISPR, which turned 10 years old this year, has led to innovations in medicine, evolution and agriculture
What is CRISPR technology?
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats.
It is a reference to the clustered and repetitive sequences of DNA found in bacteria, whose natural mechanism to fight some viral diseases is replicated in this gene-editing tool.
It usually involves the introduction of a new gene, or suppression of an existing gene to eliminate or introduce specific properties in an organism.
It has been happening for several decades now, particularly in the field of agriculture, where genetically modified variants, with specific desirable traits, are regularly developed.
CRISPR is simple and still far more accurate and it does not involve the introduction of any new gene from the outside.
Its mechanism is often compared to the ‘cut-copy-paste’, or ‘find-replace’ functionalities in common computer programmes.
A bad stretch in the DNA sequence, which is the cause of disease or disorder, is located, cut, and removed and then replaced with a ‘correct’ sequence.
The tools used to achieve this are not mechanical, but biochemical specific protein and RNA molecules.
The technology replicates a natural defence mechanism in some bacteria that uses a similar method to protect itself from virus attacks.
Do You Know?
The developers of the CRISPR technology, Jennifer Doudna and Emmanuelle Charpentier, won the Nobel Prize for Chemistry in 2020.
Why is it called a revolution?
Improved quality of life: CRISPR has begun to deliver on the near unlimited potential to improve the quality of human life.
Correcting genes: The technology enables a simple but remarkably efficient way to ‘edit’ the genetic codes of living organisms, thus opening up the possibility of ‘correcting’ genetic information to cure diseases, prevent physical deformities, or to even produce cosmetic enhancements.
The first task is to identify the particular sequence of genes that is the cause of the trouble. Once that is done, an RNA molecule is programmed to locate this sequence on the DNA strand.
After this, a special protein called Cas9, which is often described as ‘genetic scissors’, is used to break the DNA strand at specific points, and remove the bad sequence.
CRISPR-Cas9 is the most common, cheap and efficient system used for genome editing.
CRISPR stands for ‘clustered regularly interspaced short palindromic repeats’.
CRISPR is the DNA-targeting part of the system which consists of an RNA molecule, or ‘guide’, designed to bind to specific DNA bases through complementary base-pairing.
Cas9 stands for CRISPR-associated protein 9, and is the nuclease part that cuts the DNA.
The CRISPR-Cas9 system was originally discovered in bacteria that use this system to destroy invading viruses.
Deoxyribonucleic acid (DNA):
Deoxyribonucleic acid (DNA) is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA.
Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).
Mitochondria are structures within cells that convert the energy from food into a form that cells can use.
The information in DNA is stored as a code made up of four chemical bases:
DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule.
Together, a base, sugar, and phosphate are called a Nucleotides are arranged in two long strands that form a spiral called a double helix.
The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.
An important property of DNA is that it can replicate, or make copies of itself.
Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases.
This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.