I especially like how deliberately precise and consistent you use the terminology. Most lecturers eventually start using alternatives with the same meaning from their experience and it confuses me while trying to grasp the information that's new to me. And you don't skip steps. Most lecturers go very slowly in tiny steps in the beginning and right where it gets tricky they take a leap and they've lost me. Exceptionally well done. Thank you so much.

Easy to understand explanation about the CRISPR / cas9. Thanks.

What a great video, got here at random and rarely for youtube, I came away knowing something i didn't when i started watching - as a software guy i'm kinda fascinated about how similar gene strings appear to be to serial comms protocols - start and stop sequences and interrupting the message to insert or delete data

Thank you so much, you did a great job, I like the fantastic way you explain crisper

Thank you Tessa

Thank you very much. Great explanation. It helped me a lot.

Amazing explanation, so simpy and easy way. I love it. Please make more videos. You are doing GreaT!

Its a great explanation of CRISPR/cas 9 and its effects,thank you

wow i understood that better then what was given to us by the lecturer THANK YOU

Good video. Nicely paced, clear diagrams.

Thanks a lot for beautifully described

Best CRISPR video so far. Showing implication of gene editing

you did a very very good job, really appreciate it. hope you could do more videos like this, once again thank you

Great video!

Cool video, I’m a genetics student as well. you’re a wonderful teacher I subbed!

Thank you very much for this informative video!

It was so cute and informative 😍 thanks a lot.

I'm a chinese student.This is the clearest video about CRISPR i have ever seen,thanks a lot!

Can you please make a video on RNA and Dna?...would help to understand the video better..

That's wonderful..! Thank you♥️

Very clear explanation :)

Thank u,good explanation

Great explanation. Thank you.

i love you for this, simply simple

I need an accurate and precise practical example in the field of zoology???? Will you plz share it

Thanks you very much!!

More videos?

Did anyone applied this technology on animals...if yes...then what was their results?????

Thanks for breaking this down. Question though. When this is done, how does it get to the other cells in the body? Does it spread the correction by copying it to the other cells?

@tessamontague4670

5 жыл бұрын

Good question. I'll give you a detailed answer below, but the main point is the mutation can never spread through the body. In order to make a homozygous mutant (-/-), in which the mutation is present in every cell of the body, you need parents who have the mutation in their germ cells (AKA sperm and egg). If the sperm and egg have the mutation, all subsequent cells that are made from the fertilized egg will have the mutation too. Long answer: Let's say you want to make an albino fish to study the effect of UV rays on albino skin. To make your albino fish, you would inject Cas9 and a gRNA targeting the fish pigment gene into a 1-cell fish embryo (a fertilized egg). It may take a little while for the Cas9 to cut the DNA, so perhaps the fish embryo has already divided into 4 cells when the mutation is made. This means that only 1 of the 4 cells contains the pigment mutation, and therefore after the embryo has continued to divide and grow for 2 months, approximately 25% of the cells in the adult fish will contain the mutation (because each time a cell divides, it copies the DNA from the parent cell). We would call this a "mosaic" animal because it's a mix of normal (wild-type) cells, and mutant cells. Because we've targeted a gene required to make pigment, you would see the skin being a mosaic of pigmented and unpigmented skin. To get a fish that is 100% mutant (a "homozygous" fish, which is completely albino), we would hope that some of the cells in the mosaic fish that have a mutated copy of the pigment gene are sperm or egg cells (depending on if it's a male or female fish). Let's say we have a male fish, and some of its sperm cells derived from the original mutated cell, and therefore inherited the pigment mutation. We would cross this mosaic male fish to a wild-type (normal) female fish. Some of the eggs from that cross would be fertilized by the mutant sperm, and therefore these animals would be heterozygous (+/-) because they'd have one normal copy of the gene from the mum fish, and a mutant copy from the mosaic dad fish. We still don't have the homozygous fish, but we're getting close! We would now wait for these heterozygous fish to grow up. Once they're adults, we could cross these siblings to one another, and 25% of the resulting embryos would by chance inherit a mutant copy of the gene from the mum, and a mutant copy of the gene from the dad. These would be homozygous (-/-), albino fish. ---- It's always possible that when you inject Cas9 and the gRNA into a 1-cell embryo, they are very efficient at cutting both copies of DNA at the target site before the cell has divided into 2 cells. If this happens, every cell will inherit the mutant copies of DNA, and therefore you would immediately have a homozygous mutant!

@Hells2TheYea

5 жыл бұрын

I've been to a lot of videos and articles that try to explain this stuff and so far, you have been the most coherent. You break it down step by step. So thanks for that. Really appreciate the simplistic approach. It's very cool how cells and stuff work. I should have been clearer with my question though. You did answer half of it. But my question was more geared towards already living animals. Trying to cure diseases. Do you think that will be possible one day? To inject cas9 into an already living animal or human to change mutated genes? That's billions of cells, right? So they would need something to spread that and make all the other cells copy it. Perhaps nanotechnology? Or putting a virus in with the cell so that it spreads? Does that make sense?

@tessamontague4670

5 жыл бұрын

Ah gotcha. Also good question! Yeah, delivery is a big issue when working with humans because, as you said, you could only target a few cells using an injection method. Theoretically you could treat an embryo if you already knew it had a genetic disease, but there are ethical issues with that, and you may only realize a person has a disease once they're an adult. The most common method used right now in CRISPR clinical trials is treating patients with genetic blood disorders because you can remove some of the blood stem cells, deliver the Cas9/gRNAs, ensure that the gene was deleted in the stem cells, then replace them. Then all subsequent blood cells made from those stem cells should be healthy/corrected. Organs are more complicated. One method people are using is fatty particles that contain the Cas9 protein and the gRNA to target a liver disease. Since the liver naturally filters fats from the blood, doctors can inject the fatty particles (containing Cas9/gRNA) into the blood, and they'll naturally get delivered to their target, the liver. For other organs where you can't rely on specific targeting via the blood, people are trying viruses, as you suggested. However, these are more risky because you can't insert protein and RNA into a virus - you have you insert the DNA that encodes the Cas9 protein and gRNA, which means that the final destination of the virus could keep making more and more Cas9 and gRNA for a long time. Also, it's hard to control exactly what the virus infects. Ideally we need delivery methods that are very specific so that you don't start cutting the DNA throughout your body. Theoretically, if Cas9 is only targeting the one 'defective' gene (thanks to the gRNA), it would be fine to have a virus infect your whole body and start correcting the mutation. But Cas9 can have off-target effects - cut other locations in your DNA - so you could potentially have some undesired effects if a virus delivered Cas9 to all of the billions of cells that make up your body. I hope that answers your question! There's some interesting details about the current delivery methods/clinical trials here: www.newscientist.com/article/2149129-were-nearly-ready-to-use-crispr-to-target-far-more-diseases/

@Hells2TheYea

5 жыл бұрын

Thanks for the info and responses. Appreciate it. :)

@mmd123king6

2 жыл бұрын

@@tessamontague4670 teacher when a dna is cut will the cells produce it again knowing what dna or gene was cut from the help of condones codes that have a saved data in the geneomoes? I have a exam comming up 😥 pls help

Hey boss, nice work ;D

Very good video Tessa, simple, interesting, accurate and enjoyable. Please keep sharing.

Can you help stroke recovery

Great educational video! CRISPR-Cas9 is literally why I'm getting a degree in biology.

Thank you so much :D

Can you also activate genes with this technique?

@tessamontague4670

5 жыл бұрын

Yes! There is a version of Cas9 that researchers have inactivated so that it binds to DNA but doesn't cut it (called dCas9). You can combine dCas9 with a gene activation protein (called VP16 or VP64) and a guide RNA (gRNA). When combined, the gRNA will guide dCas9 to a target gene, and the VP16 domain will cause the gene to be activated.

THANK YOU THIS HELPED A LOT

incredibly helpful

Hence, the birth of Tessa Therapeutics 🤣

absolutely lovely explained and very insightful! also, tessa strikes me as very likeable

It can be more beautiful on writing tablet.

You are super nice and it is very clear and understandable. Please go on!

Great video Tessa. Thanks for loading!!

Could you explain why does the double strand DNA becomes single strand when the CRISPR-CAS9 reaches it? Does it use any enzyme or it just break the bond between the strands?

@tessamontague4670

6 жыл бұрын

The Cas9 protein has "helicase" activity, which means it is capable of unwinding the DNA. If you imagine grabbing onto each strand of DNA in the middle of the double helix, and pulling on them, you would separate the two strands (and cause tighter coils on either side of the open region). Cas9 does this, which enables the gRNA to form basepairs with just one of the strands of DNA. Cas9 has multiple protein domains with different functions - so one domain of the protein can unwind DNA, and another domain can cut DNA.

@VictorLee2019

6 жыл бұрын

Ohh, I was wondering if you had to use the helicase combined with the cas9, but the cas9 already has this enzyme. Thanks for your fast answer!

HOW GRNA DESIGN TO PAIRING WITH SPECIFIC GENE\ FUNCTION OF TRACR RNA?

Thank you very much for teaching me this

What prompts natural mutations - Evolution per se for survival. Luck? Stress? The more biodiversity, overpopulation, the more luck against extinction.

Ok but why is the non fluffy dog sad in the beginning but in the end is happy? And all the fluffy dogs are happy all the time?

Can crisper be used to alter mean people?

love your dogs:)

What’s the price

Nice

Hi Tessa, how long is the homing RNA? Also, where in the gene would you do CRISPR in? The beginning? The promoter?

@tessamontague4670

6 жыл бұрын

The part of the guide RNA that binds to DNA is 20 nucleotides long. But the full length of the gRNA (including the part that folds and binds to Cas9) is 100 nucleotides. Yep, you would usually design your gRNAs to target the beginning of the gene. When Cas9 creates a double-strand break, you get a small deletion (or insertion) that causes a frameshift, which then creates a premature stop codon. As you probably predicted, if you designed the gRNA to bind near the end of the gene, the stop codon would also be near the end of the gene, so most of the protein would still get made. Therefore it's possible the protein would still be functional, so it wouldn't be a "knockout". If you design your gRNA near the beginning of the gene, the premature stop codon will also be near the beginning of the gene so the protein that is made is so small, that it will likely have no function at all. It also might get degraded. Usually people don't target promoters for regular knockouts because if you create a small deletion or insertion in the promoter, it may not have much of an effect, since the DNA doesn't have a 'frame' that can shift (because it's not translated into protein). A small deletion would only have an effect if you happened to remove a binding site for a regulatory protein. Some people use multiple gRNAs to remove the whole promoter if they want to understand how the expression of a gene is regulated, but for regular knockouts, it's much easier to just design gRNAs to target the beginning of the coding sequence (AKA downstream of the promoter). I hope that helps!

Also if a part of DNA is cut and is inserted with another( drawn with red pen)....then what actually degrades? If a new part is inserted it should be fine right?

amazing. I hope for more vidos. Thank You.

Cute scientist girl ... now please make me a video on how we replace defective genes with good ones without messing up the stop codon - i.e: homologous repair with a replacement piece of mRNA added to the guide complex ?

Hi Tessa, what's the role of the PAM sequence in the CRISPR system?

@tessamontague4670

6 жыл бұрын

The PAM sequence is next to the gRNA target sequence on the DNA, and is needed for Cas9 to bind to the DNA. If there isn't a PAM sequence next to the gRNA target sequence, even if the gRNA can bind to the DNA, Cas9 won't cut the DNA.

It sad she stopped the channel 😢😢

One or the other -a schematic or an explanation - would be better than trying to follow both at the same time.

Hii teesa what is the mean associated protein 9

Well... this has been love at 1st sight! ... I mean: subscription at first sight! ;) Thanks! I can hardly remember a lovelier way of learning.

So cas9 goes about unwinding all DNA it comes into contact with. I don't understand how cas9 knows when or when not to unwind

@tessamontague4670

4 жыл бұрын

Good question! Cas9 will only make a cut if the gRNA finds a matching sequence, and if this sequence is upstream of a sequence called “PAM”, which is usually NGG (N=any nucleotide). When the Cas9-gRNA complex is searching for its target, it first looks for the PAM sequence, and if it finds it, it starts unwinding the DNA, and only continues so long as the sequence matches the gRNA. According to Sternberg et al: “sequence homology adjacent to the PAM is necessary to initiate target duplex unwinding until the reaction has proceeded sufficiently far (~12 bp, approximately one turn of an A-form RNA:DNA helix), such that the energy necessary for further propagation of the RNA:DNA heteroduplex falls below the energy needed for the reverse reaction”. You can read more here: www.ncbi.nlm.nih.gov/pmc/articles/PMC4106473/ Figure 3 and 4 are most relevant to your question.

@mainebehavioralhealthcare669

4 жыл бұрын

@@tessamontague4670 and it can find a matching sequence without unwinding the dna? Does it just come to close proximity to it and it can detect the correct sequence

Your handwriting is very beautiful so does your knowledge and you.

@mauwakie7065

6 жыл бұрын

ravinder singh _

@aksshaysharma96

5 жыл бұрын

Tharak

@zach9620

5 жыл бұрын

rapindia.

@7190707

5 жыл бұрын

Aww, RS is smitten!

I get loved

Very lucid.

I wonder what would happen if we made Case 9 protein into an origami and we could imagine that one unfold of the case 9 origami as a result of the guide RNA Would cause its molecular pincers to cut the DNA And this would cause and unfolding action in another section of that would result in storage DNA being released and then bonding covalently to they remove sections enabling the case 9 protien and this would cause an unfolding action in another section of that would result in store DNA being released and then bonding covalently to the Wound in the DNA as we can imagine Guide are in a inside of the protein controls the origami folding and unfolding action based on proteins I could attach to receptors and these proteins being smaller I suppose it’s almost like a clockwork mechanism enabling the case 9 protein To unfold and integrate the DNA it was carrying along with it enabling the case 9 protein to do more Then just cut DNA it can now also add DNA sequences

Funny part is who invented this has a most of 40 likes in his videos and only few k views

pretty

Amy FaraFowler!!!

Hey you are so cute ... Love you.

suprbbbbbbb

I would like to cure schizophrenia, but when will gene therapy be realized?

@tessamontague4670

5 жыл бұрын

Unfortunately not soon. Schizophrenia is a complex disease that seems to be caused by lots of factors. It may be partially caused by genetic mutations, but probably in multiple loci in the genome, and different people have different mutations. So you can't make a single, corrective mutation with CRISPR that will cure schizophrenia in the way that we will be able to for genetic diseases like cystic fibrosis or Duchenne's muscular dystrophy.

@user-lv2ov4gq1x

5 жыл бұрын

@@tessamontague4670 When is your prediction?

@7190707

5 жыл бұрын

Not soon...learn crispr, study the disease and maybe you'll be the one to bring it to the world!!

Had enough of the annoying pen cap clicking. I hope you don't work in a cubicle doing that.

I love you!!!! You're so beautiful and brilllant... LOVE AT THE FIST SIGHT