Gene Editing with Crispr - Cas9
What is CRISPR-Cas9 and how does it work? How do we edit genes? Jennifer Doudna, biochemist at UC Berkeley, explains. The gene editing technique, created by UC Berkeley biochemist Jennifer Doudna and her colleague, Emmanuelle Charpentier, director of the Max Planck Institute of Infection Biology in Berlin, has taken the research and clinical communities by storm as an easy and cheap way to make precise changes in DNA in order to disable genes, correct genetic disorders or insert mutated genes into animals to create models of human disease. CRISPR-Cas9 is a hybrid of protein and RNA – the cousin to DNA – that functions as an efficient search-and-snip system in bacteria. It arose as a way to recognize and kill viruses, but Doudna and Charpentier realized that it could also work well in other cells, including humans, to facilitate genome editing. The Cas9 protein, obtained from the bacteria Streptococcus pyogenes, functions together with a “guide” RNA that targets a complementary 20-nucleotide stretch of DNA. Once the RNA identifies a sequence matching these nucleotides, Cas9 cuts the double-stranded DNA helix. Read more about CRISPR: ****** Video by Roxanne Makasdjian and Stephen McNally Cas9 Apo Structure image by Ben.lafrance CC BY-SA 4.0 ****** CRISPR animation provided by the Innovative Genomics Initiative ****** ****** ****** ****** ******
Tip: Highlight text to annotate itX
I think the thing that's amazing about science
and about biology for me is that there's always more
to be discovered, and every time we feel like we've figured
something out, it seems to open up several more questions.
(gentle percussive music)
Scientists have appreciated for a long time
that once we understood the DNA sequence in cells,
if we had a tool that would allow easy manipulation
of that sequence, that that would be
a very powerful kind of technology.
(gentle percussive music)
CRISPR is a technology for changing the sequence
of DNA in cells in a precise fashion to correct mutations
that might otherwise cause disease.
It's going to enable a lot of science to be done
that was impossible to do in the past.
So the way the CRISPR technology works is
by the action of a protein called Cas9 that functions
like a molecular scalpel for DNA.
The CRISPR Cas9 system has an amazing ability
to recognize a particular DNA sequence in a cell that may be
malfunctioning, and then disable it by cutting the DNA.
We call this gene editing, and we can use it
to disable or repair a mutated part of the gene,
which may be causing disease.
For Cas9 to find the malfunctioning DNA,
we attach it to an RNA sequence
that matches the DNA sequence we want to edit.
Then we put this RNA Cas9 combination into the cell.
It finds the mutant DNA and uses the chemical reaction
to cut the DNA strand right at the spot
where it's malfunctioning.
After that, we can sometimes insert the correct version
of the gene for the cell to work properly again.
It's a very exciting technology that's going to do
a lot of good in human society and for human health.
It stretches from human therapeutics
to agricultural applications to thinking about
how do we make better biofuels.
These would be incredible outcomes, I think,
of using this kind of technology in the future.
(gentle percussive music)
