In this video I'll be talking about the difference between RNAi and CRISPR technology.
RNAi stands for interference RNA and naturally occurs in eukaryotic cells.
There are two types: microRNA, which is endogenous and comes from a single strand of RNA, and small interfering RNA, which is exogenous
and comes from a double stranded RNA. Both types of short RNA affect mRNA, which in turn affects protein synthesis.
MicroRNA works by directing the RISC to the target mRNA strand.
The RISC is composed of an Argonaute protein and either one of the short RNA.  Part of the micro RNA, called the "seed", pairs with
the target strand.
Imprecise pairing inhibits translation. The image to the right shows how dicer, a nuclease, preps the microRNA. The micro RNA
strand then binds to an Argonaute protein,  forming the RISC. The RISC is then guided to the target strand, where micro RNA binds imprecisely
to mRNA. Small interfering RNA works by using precise base pairing.
Instead of functioning as a lock like micro RNA, siRNA tells RISC to cleave the complimentary strand, resulting in the degradation of the
specific segment. Unlike micro RNA, siRNA can only target and degrade its complementary strand.
Another form of gene editing is CRISPR technology.
CRISPR stands for clustered regularly interspaced
palindromic repeats and naturally occurs in prokaryotic cells. CRISPR cleaves DNA instead of RNA and can be used on all types of DNA.
Unlike RNAi, this method results in a permanent change.
This method uses a guide RNA
consisting of CRISPR RNA and tracrRNA and a Cas-9 protein. The Cas-9 cleaves the DNA up until the PAM sequence.
The altered DNA then repairs itself. Although RNAi and CRISPR technology both affect gene expression,
there is a big difference in process and outcome. For an example, I'll use the gene that affects the appeal of cilantro.
Let's say gene A is the gene that causes
cilantro to taste soapy.
This gene causes your olfactory nerves to have a high binding specificity to aldehydes that come from cilantro.
If both methods work,
and I want to study the effects of inhibiting gene A, I would choose to use RNAi
This is because RNAi is temporary. This method also does not affect DNA, which may reduce the risk of synergistic mutation.
I would use CRISPR technology to permanently alter someones hate for cilantro.
Thanks for watching
