DNA sequencing | Biomolecules | MCAT | Khan Academy

[@cocokat1268]

Can you make a video on Next-Generation Sequencing please?? It would be so appreciated!!

[@phoebedu93]

Thank you! I'm currently learning about this in pre-med and it left me pretty confused. This helped greatly!

[@derrickacheampong6422]

are you a medical student now?

[@usmanshami1238]

I LOVE YOU Khan Academy you're the BEST. Have multiple tabs opened right now doing genetics. You make the most screwed up pain in the ass topics easy as nothing ! WOW. just WOW

[@MisterRazz]

@1:11 you're missing your triphosphate groups to make these deoxynucleotides (dNTPs) and dideoxynucleotides (ddNTPs).

[@lilycarrington5132]

I've been struggling to grasp how DNA sequencing works, but when I watched your video it finally just clicked. thank you!

[@ithirstyforknowledge]

excellent video to give a picture of what sequencing is to a newbie like me

[@AwesomeRecipes100]

Great video. Thank you

[@nadiaballard9160]

Great video!

[@ploplo1200]

so good

[@sciencenerd7639]

thank you

[@parisarp6127]

You are really good teacher i dident understand this aces before i saw you video

[@bryanttan7591]

awesome explanation

[@arzangsyed8386]

Incredibly concise, thanks!

[@basketballtim2009]

Excellent video, much appreciated.

[@preciousmaelane274]

Where do we get the ddNTPs and the dNTPs that we are adding which cause termination of transcription? Are they made in the lab or?

[@languageandmana9255]

I wish it would be more detailed. But thank you so much

[@mangeshkritya4135]

Please can you elaborate on the last segment. How does the computer 'by reading out the last DDNTP can sequence' can come up with the actual DNA sequence?

[@MSadamgasm]

the base of the ddNTP is either G, C, A or T thats how it tells

[@tatehop]

Each base (G A T C) generally has a different flourophore attached so the color visualized will tell you what base it is

[@WaterGlider]

But the sequence in which it breaks up is random no? How does the computer know the actual sequence?

[@estilomaniaco]

Not sure if I understand your question but when you use the PCR technique, you have a DNA target of interest that u want to replicate, so the sequence that will come will always be the same one (that target) just in different sizes (because of how fast a ddNTP is added)@@WaterGlider

[@learn-site7708]

I had your question but when I read more about that I found my mistake and that is ddNTP doesn't randomly attach to the last part of replicated DNA. It will attach instead of normal nucleotide while DNA replicating. Let me give you an example it will clear. Imagine that we have GCTAGTATAG stand DNA we start to replicating that using PCR. So it starts to replicating, CGAT when C wants to attach at the continue of replicated DNA, fluorescently tagged C ddNTP attached instead of normal nucleotide ( coincidentally ) . Also, when it attached, replicating is stopped. So when this event occurs in wide amount of DNA we can sequence DNA. we use the Gel electrophoresis for sorting DNA strings with size.

[@1david12]

1:11 that is a nucleoside

[@熊鞋子]

Thanks, you made my day!

[@fadeskywards1245]

Excellently explained. Thanks so much!!

[@lucianocilio4937]

What if by a random chance, in different readings, the ddNTP attaches & terminates the polymerase at the same nucleotide, with consequence of generating several copies of same sequence? Would this cause confusion at electrophoresis reading? Or not because it's still the same length? For example, if we had: AAGACATT... and at two or more times the ddGTP attach on the first G (since attachment is random and repeated a lot of times), it would end up giving two strands of TTC. Then these two be run through electrophoresis.

[@alikashour6373]

I barely could hear you could you raise ur voice in other chapters... but anyway ur method of elination is pretty good

[@Soulblade727]

Not to nitpick or anything, what you drew up were nucleosides. Good video though...

[@themesaregreat]

+Brandon Naraghi Are you talking about the ribose sugar? Ribose only has 5 carbons, not six... somebody doesn't know their chem or bio haha :)

[@andrenickatina415]

+themesaregreat you're completely right, I was getting mixed up. thanks!

[@kedaang]

+Soulblade727 lol i went back and forth looking up the "nulceotide" which actually was a nucleoside.

[@gapehorn2917]

uhm, he technically puts in the base by labelling it but not necessarily drawing them on so they are technically still nucleotides not nucleosides.

[@aizasaed170]

thank you for this!!

[@fareshejazi2297]

i understand the method but what is it used for

[@emilopez4957]

my speakers aren't working well, and I wanted to know if anyone could help me out by answering my question. Where is DNA send off to get sequenced?

[@eintroll8792]

labour

[@manalidesai4347]

question how is it recognising size

[@bobl9555]

5 minutes of awesome explanation. Thanks!

[@VisionControl1998]

dNTP is deoxynucleotide TRI PHOSPHATE - why do you not show the phosphates?

[@kiruthigaelango3626]

Where I can download cancer dna sequence dataset can anyone share link plz

[@mrLogan-st6tb]

thanks, but if you type by keyboard will be good

[@Death_User666]

Talk into the microphone bro

[@aljosephsolis4039]

Change G to X or whatever T to whatever A to whatever C to whatever Stop following the GTAC,ATGC,GATC.

[@rastafarai3712]

I’ve never wondered that lmao

[@malumaha5821]

Pls upload chromosome walking elaborately pls

[@ElloBoppit]

Not to be picky but he called the nucleoside at 1:11 a nucleotide. Remember, nucleosides have the phosphates linked to it.

[@eintroll8792]

Not to be picky but nucleosides DO NOT have the phosphate linked to it. At least critisize right...

[@jasonsmith8210]

Wait. You just chopped up the DNA... But then you read 6.4 billion base pairs in order to do a match? I don't know. This sounds far fetched.