Hello I'm Shin Jung Lee and today, I'm gonna introduce you about CRISPRs
So what is a crisper?
Crisper stands for clustered regularly interspaced
Short palindromic repeats now you'll get why scientists just call it crispers right crisper is a scissor of DNA
Now let's take a practical example for e.coli and bacteriophage. Now first
bacteriophage inserts its viral DNA into the cell membrane to duplicate more
bacteriophage which can kill the bacterium. But in the CRISPR locus if bacterium already has the same
information with viral DNA in spacer DNA so they
transcribe this DNA into RNA and forms a crisper RNA and for cas genes they transcribe and translate
protein, and they make cas protein now cast protein and crispr RNA(crRNA)
bonds together to form a complex
and they attaches to viral DNA and if the RNA and DNA's
Information matches, it breaks up the DNA
scientist Jennifer Doudna and Emmanuel Charpentier discovered this phenomenon while studying
streptococcus pyogenes. Now this bacterium do use cast 9 protein and crispr RNA
But they also use tracer RNA(tracrRNA) which holds the crispr RNA in place. So what they did is
They merged these two RNAs and named it tracer RNA and crispr RNA
chime(a)ra or guide RNA so how this works is first heliase breaks up the bond and
guide RNA sees if it matches the genetic information
And if it matches the nuclease which is an enzyme and depicted as scissors
Breaks of the bond. So what if the bond breaks? well the DNA attaches together.
So let's say a bond is broken up by
cas9 protein and guide RNA then the DNA either
adjusts the broken part by make little bit of change or mutation or it gets repaired with
The additional genetic information, so it can be used to cure diseases
now let's see how it works in DNA first the heliase the enzyme breaks of the double strand
and then the guide RNA sees if it matches the genetic information
And if it matches the nuclease breaks up the bond like this
So what happens to the broken DNA?
well, if there's an additional genetic information floating aside it then the DNA adapts it
and then to adjust it the DNA adds some more nuclear information like this
