dna replication

[xxGlitznGlam]

....why can't you be my professor

[xxGlitznGlam]

Unj... So they don't reconnect

[aanaceci]

better explanation than my cellular and molecular biology book

[unj008]

Why do you need to lay out the RNA primers?

[lastheat32]

uuurghhh!!!! waste of time!!!!!!! why in the world is that!! full of stop i can't watch it continuously >:(

[luckygain]

Thank you so muchhhh! Very helpful.

Love your accent. hahahhahaa

[TheNoreentaylor]

Hugely helpful

[itsgiahan]

Why can't AP textbook talk like this????? thanks sooo much

[BUNNA9]

can u plz throw some light on the mechanism of loop formation on the lagging strand during replication????

[bstbstbst2010]

@BUNNA9 By mechanism do you mean the chemcial interactions that actually make the Okazaki fragments or the reaosn why they need to be made?

[BUNNA9]

@bstbstbst2010 Not the chemical interaction not even the reason why it is made, i just want to know how actually the loop formation takes place.....

[maca24601]

Hi!! So one question... Is this pretty much what happens during the pcr when u are replicating a strand of DNA ??

[BriansBiology]

@maca24601 Basically yes although in PCR there is no problem with the DNA strands being anti-parallel so the 3' to 5' firection of DNA polymerase doesnt matter. Also in PCR the DNA is usually single stranded.

[useurcamera]

woot! thanks! although I only study regular freshman bio. ::D

[BIOLOGY181GCU]

This video was very helpful...

[mbenzo17]

brilliant explanation.... thorough and succinct.... i wish my professor made it this easy -_-

[Svetlania1]

I love this video and the explanation! Thanks a lot!

[LJ3pg23]

Thank you! Just made sophomore level genetics at tulane much easier!

[BriansBiology]

@LJ3pg23 glad to hear this

[soumyasayujya]

can u plzz put up a vedio on water relations of plants...??.......tat s at acent of sap, absorption of water by roots n all??....pllzz cos ur 7 min vedio has done wonders on my knowledge abt dna replication for which i hav spent an entire years reading a lot of books...should hav known abt this vedieo be4!! :(....and m really weak in water relations of plants...need help!!..we hav our pre finals next week!!.... help plzzzzz!! soumya.sayujya@gmail.com

[BriansBiology]

@soumyasayujya I will try but I may not get it up by then....

[xHaniffax]

Your accent is so sexy.

[BriansBiology]

@xHaniffax thanks! lol

[pumpernickel12]

Professor Moody?

[BriansBiology]

@pumpernickel12 no but I am irish as I assume he is.

[neadr2004]

why can't i have a teacher like that?:|

[BriansBiology]

@neadr2004 let me know what else I could help with.

[454ffv]

can someone please explain to me why rna primers are used in replication instead of say dna primers?

[soumyasayujya]

@454ffv cos for dna replication to occur...it needs initiating enzymes like rna pimers..which makes short stretches of rna for initiating dna polymerase........as to ur question....as rna primer s also called rna polymerase...i guess dna primer may be dna polymerase.....so...dna polymerase needs rna segments for dna replication!!...... got it??...any more doubts regardin this mail me on soumya.sayujya@gmail.com ok??

[SnazzyPumpkins]

@BrainsBiology thank you so much, this helped me understand the underlying basics of my biotechnology class which we're having midterms in next week. Thank you!

[BriansBiology]

@SnazzyPumpkins happy to help.

[wizardtjai]

@catalaaya it is, but dont forget that the polymerase goes from 3 to 5. leading strand with 5-3 is already made, you only need to make the other part (3-5) , just remember that the 3-5 strand is the one who is made :p , no exceptions

[MegaMANOBILLI]

BEST VIDEO EVER:) THANX A LOT

[Catalaayaa]

isnt it 5 to 3?? :S the direction

[AnTiCOCAlAr125]

this video really helped me.thanks a lot Brian!

[BriansBiology]

@AnTiCOCAlAr125 no problem!

[FeadogMhorCeoltoir]

I was having trouble memorizing all the proteins involved (especially since I'm also trying to memorize a list of functional groups for my O-chem class right now, too) and this made everything quite clear! Thanks so much!

[BriansBiology]

@FeadogMhorCeoltoir good luck and thanks for the nice comment!

[lanahussain]

Made everything so unbelievably clear, thank you :)

[BriansBiology]

@lanahussain no problem, thank you for the nice comment! live n learn.

[FateStayNightOST]

DNA polymerase attaches to the RNA primers and begin elongation, the adding of DNA nucleotides to the complement strand

The leading complementary stand is assembled continuously as the double-helix DNA uncoils.

The lagging complementary strand is assembled in short Okazaki fragments.

The Okazaki fragments are joined by DNA ligase.

The RNA primers are replaced by DNA nucleotides.

[FateStayNightOST]

Helicase unwinders the DNA, producing a replication fork. Single-strand binding proteins prevent the single strands of DNA from recombining. Tpoisomerase removes twists and knots that form in the double-stranded template as a result of the unwinding induced by helices.

Primase initiates DNA replication at special sequences (origins of replication) with short segments of RNA nucleotides, called RNA primers.

[Carefree0101]

So, I am studying for the MCAT's and was agonizing about lagging-strand formation. I needed to "see" the 3D process to understand. Now it is perfectly clear. Thanks for the help!

--Future neurology student

[DDDelicious22]

helpful, thank you! I like your accent too, where are you from sir? :)

[BriansBiology]

@DDDelicious22 Ireland. Originally live in asia now where I work, hence the jungle birds in the background.

[Chesterfieldbuff]

Best description on the web. Thank you!



[majockus]

Has anyone unraveled the language yet? I heard it was Hebrew and shows " The Word" giving life?

[BriansBiology]

@majockus ?



[PKMNJFKID]

I remember my AP Bio teacher in high school would make me teach this to the other students sometimes because I would get it. I watched this because I had forgotten it (though I got a 3 on the AP exam) and it brought back my old question (IF ANYONE COULD ANSWER IT PLEASE!): Why does DNA replication initiate with a RNA fragment instead of a DNA fragment? Is it because DNA Polymerase III can't attach to a DNA fragment? Does it have to do with the three and five prime ends?

[BriansBiology]

@PKMNJFKID Basically yes. Polymerase III needs an RNA primer because it will chemcially bond to only this molecule in the correct way.

[pileofmarshmellows]

Yay! The people in my class, including me, have to write a SONG about this. Thank you soooo much! And to any other 8th graders that have to write a song about this for homework, good luck.

[jess8112]

What about IB students :(

[BriansBiology]

@jess8112 lol Actually my school is now going to run a dual IB/AP program. So it is now officially fot both and anyone else who wants to learn.

[maravillosabri]

Just used this to study for my Bio final. Wow thank you so much!!

[BriansBiology]

@maravillosabri Excellent! Good lcuk with your exam!

[BiologyTerrier]

Thanks for helping me review for my finals! Great video.

[svufan9]

Thank you so much! this helped me much more than my book

[AnTiCOCAlAr125]

thank you so much for this video Brian!

[kirsticatification]

Do I hear birds in the background?

[BriansBiology]

@kirsticatification lol yes I live in the jungle......

[guitarruler1453]

the best!, i got a 97 on this test on protein synthesis and dna replication beccause of this video, the highest grade in the class! she asked how i studied, pointed out your video, and we now watch it for our midterm exam!

Thanks again

guitarruler1453

[BriansBiology]

@guitarruler1453 Love it! Thanks!

[morrisdecat]

Sorry for all the questions but I am always trying to understand things as I see them.

[morrisdecat]

Thank you for the responds.

Also, how does dna strands navigate to interact with all their duties?

I could not help but to also see polymerase navigating like it knows were to go and do its job. what sort of drive does it have to move around so elegant?

All of the videos shown on you tube are very nice, but I expected to see the components being assembled with a sensible order. All I see is proteins flying into their correct counterparts at unimaginable speeds.

[BriansBiology]

@morrisdecat Hi Morristhecat, questions are my bread and butter so keep asking! Remember that all th emolecules you see flying around are chemcials and chemicals bond to other chemcials depending on electron configurtaions and other chemcial and physical attractions/interactions. What you are aksign is like asking why does 02 bind to H to give H20, the answer is because of its chemical nature. As for polymerase its the same deal except that it continues to react along the ......

[BriansBiology]

@BriansBiology strand of DNA provided it can react along from the 3' to 5' carbons of the ribose sugar. I know it seems a cop-out to just dimiss it these attractions and interactions as just chemcial reactions but thats what it is. To understand more of why a polymerase molecule reacts specifically along the 3' to 5' DNA strand you woudl need to study its 3-d structure and know a lot more chemistry than I do. I hope you can accept that answer.

[UnspokenHonor]

Wonderful, I have been looking everywhere for a video like this, but I have a few questions. During RNA transcription, how is a gene core promoter recognized by transcription factors and not confused with other like sequences. Also, what signals the end of a gene so that transcription will stop? Thank you for your time if you get around to answering this.

[BriansBiology]

@UnspokenHonor In eukarotes there is often within the promoter a TATA box that is a sequence of nucleoptides that attracts the polymerase molecule. The TATA box, polymerase and the transcription factors make a TIC (transcripttion initiation complex) which binds apecifically to the promoter.

[BriansBiology]

@BriansBiology The sequence if fairly unique to promoter regions. The end of transcription (termination) is also due to sequences hence we get the Poly A tail at the end of the mRNA primary transcript. It is however less understood that initiation

[UnspokenHonor]

@BriansBiology Thank you greatly for the reply, but I still do not understand how the polymerase is made to stop on its trek down the DNA Chain.

[BriansBiology]

@UnspokenHonor well it falls off the end of the DNA. Remeber this is not making proteins you dont need a stop codon. It literally goes to the end of the line and falls off. DNA strands are of finite length and there is no checkpoint needed in the cell cycle here as its done when there is no more DNA for it to traverse along.

[UnspokenHonor]

@BriansBiology thank you, I was actually referring to transcription, and you gave me the term "stop codon," which has been a bid help. I only have a few more question (if you do not mind): How does a particular stop codon get recognized, and what implements the termination factors to bind to it? Do the stop codons's sequence of DNA appear in other parts of a gene, but not trigger such a reaction?

[BriansBiology]

@UnspokenHonor THe stop codon is universal for eukaryotes. It is not repeated elsewhere in the genome. There are 3 variations UAG UAA and UGA these specific sequences bind a t-RNA molecule with no amino acid but instea one that reacts with the release factors to make a complex that wont associate with the RNA due to its new chemcial structure/properties. In the DNA its the anti-codon (complementary seqnece of DNA to the RNA codons made). not codon. Also remember that the video is

[BriansBiology]

@BriansBiology DNA to DNA not DNA to proteins, try to keep both processes distinct as they have many similarities in terms of enzymes but the mechanism is very different. I will make a DNA to protein video next which I am sure will explain better than just these words.

[LadyJAnnMin]

Thank you for posting this!!!!!! I finally understand!

[morrisdecat]

Very well done, I like this tutorial. Two question? How do these enzyme like machines navigate and what directs their splendid motion?

I hate to spoil the party but could not help to see this happening.

[BriansBiology]

@morrisdecat HI The enzymes run along the sugar backbone of the DNA. The sugar backbone is pentose sugars connected form the 3' carbon to the 5' carbon. The oppoiste strand will go from 5' to 3' the enzymes only react chemcially along the backbone going from 3' to 5' so they can only move in this way. In other words chemical differences in the structure of the DNA in the two strands mean only one direction can be used.

Their motion is physical and chemcial interactions with the sugar backbon

[KimmyAshley13]

Thank you so much for posting this video. I wish my biology professor explained DNA replication where it was easy to understand like you just did in your video. It helped a lot for my biology midterm

[Jxoxoo]

my college should hire more professors like you, omg, thanks to this video... now, i'm all clear abt dna replication, which i've been reading the text book over and over again and didn't get it. NOw, i spent like less than 8 mins, and all clear now!

thanks a bunch!!!

[BriansBiology]

@Jxoxoo its comments like this that make me want to make videos like this. Thank you. 

[missbubbles9292]

WOW! I Get it now!!! Can you make more videos please!! My professor is terrible in lecturing, and its hard to visualize from reading the book, this was PERFECT!!

[mackles]

excellent video

[CrazedWalnut]

remember when DNA A and DNA C recruit the DNA B (helicase) there are 2 helicases that come one on each single strand

[TIMHILLIS]

I think he lives in a zoo

[riatblah]

I watched this for his amazing accent =P

[BriansBiology]

@riatblah tee hee thanks!

[Blade70]

Wow, this is video got through my teeny tiny brain of mine. 

[UFCemilio1]

thanks to you, i can now go into my exam with confidence on the topic of DNA replication :)

[DDhannique]

I'm still not getting the direction of flow of the DNA strand. It is read in a 5' to 3' direction right, and made in a 3' to 5' direction???

[sinhaashish935]

the best explanation offered on the topic.thank u

[ryanj11221]

im so confused its not even funny

[kirinyagahouse]

Very useful vid.

[bjmalley]

Very good with only a couple of mistakes. 1st he said that helicase starts the starts the leading strand off but it's actually DNA primase. 2nd DNA Polymerase 1 doesn't just replace uracil with thyamine. It replaces all off the RNA nucleotides with DNA nucleotides. Great video though.

[miceskin]

@bjmalley Very good comment with ONE mistake. 1st. The only RNA nucleotide that needs to be replaced is uracil because the rest are the same Nucleotides as DNA. lol :)

[bjmalley]

@miceskin No, since we are making DNA, we need deoxyribonucleotides. The RNA ribonucleotides that are laid down in DNA primase contain ribose sugars with two hydroxyl groups. We need DNA nucleotides with a single hydroxyl group. Therefore all of the DNA primase nucleotides must be replaced.

[browneyedchic77]

Thank you for posting this video, it really helped!

[alexadru93]

really helped

[GuitarHero382]

THANK YOU!!!!!!!!

[jazzykn1ght]

tiz reali help!! thx =)

[eveli55]

Thank you ! I finally get it!

[TheBobsmithers]

this video and that othere video with about 2,000,000 views are the only ones that will explain to you dna replication correctly

[lewj66]

This is AMAZING! thanks :)



[Flamification4]

I'm one of your Wells comprehensive biology student. This video is good!

[aznboii79]

Helicase doesn't lay down the RNA primer. RNA Primase does that in eukaryotic DNA replication.

[bstbstbst2010]

@aznboii79 hence the annotation saying exactly that.

[TechRambo]

THANK YOU! I'm taking 9th grade AP Biology and couldn't understand this at all from my high school teacher's crude demonstration. Haha keep up the awesome work.

[mangochutney88]

this is the best dna replication video! soo helpful thank you!

[baharsahin]

My department is computer engineering and I have to take Introduction to Modern biology lesson :( . biology is not interesting for me at all and hard to study.

but this video makes it easy to understand DNA replication.

[Drishabpoudel]

thank you...it took me alot of time to understand this concept and I still hadnt got it...but after watching this video..it took me less 6 mins to understand...THANK YOU SO MUCH

[BriansBiology]

10,000 plus!!! Next one out is membrane proteins

[miceskin]

@BriansBiology I have a question: How does the helicase know when the DNA is ready to be replicated, because I was told that more of the cells time is spent metabolising and such. what kind of indicator signals tell the (nucleus?) when it's time to replicate.

[suvas2020]

Are you sure that DNA primase leaves RNA primer, I thought RNA primase that leves RNA primer (RNA pllymerase)?

[BriansBiology]

@suvas2020 DNA primase is a form of RNA polymerase and a product of the dnaG gene. Primase is activated by DNA helicase where it then synthesizes a short RNA primer approximately 11 ±1 nucleotides long, to which new nucleotides can be added by DNA polymerase.

[suvas2020]

Are you sure that DNA primase leaves RNA primer, I thought RNA primase that leves RNA primer (RNA pllymerase)?

[ryanael]

This well done ! I still have a few questions. You said at 1:49 position, that DNA the top strand moves from 3 to 5 is that the strand or the Polymerase. I was a little confused. What I understood from is, the top strand moves from 3 to 5 and Polymers moves from 5 to 3 but wouldnt that mean it would have to come from the other direction the strand ? Next question what is the primer laid down by Helicase in the beggninng of the replication cycle ?

[BriansBiology]

@ryanael the polymerase moves along a strand of DNa from 3' to 5' and lay down anti-parallel DNA whihc would then be 5' to 3'.

The primer is simply a piece of RNA which allows tyhe polymerase to bind, it acts like an enzyme in this way.

[aminikha]

this is so much better and clearer than my biochem teacher explained. sky and ground. u cant compare betw the two

thank u

[drzandy]

Awesome!! Im a Med student in the caribbean and this video has been so helpful for my molecular biology class!

[Telepcanin]

Only video on Youtube that hasn't failed to explain dna replication correctly.

[mimalavi00]

Muy bueno, gracias desde México. Very good video. Thank you

[btonka3006]

It helped me a lot; thank you :)

[clgeller]

thank u so much!!

[BriansBiology]

@clgeller no problem

[benderquack]

Great Video!! explained clearly!

Could you do a video for transcription and translation?? that would help me so much

[satirehunter]

thank i passed my ap bio today

[xTHExPASTxISxDEADx]

thanks, this helped a lot

[marriah3330]

Now I totally understand the okazaki fragments, why they are there, and how they are joined together thank you- bio test tomorrow!

[ailhsa]

great vid. Can you do transcription and protein synthesis as well?

[ahjustmethen]

yeah i second that, you explain very well!

[nothingnothing2]

greattttttttttttttttttttttttt ! u should be my teacher.

[BriansBiology]

I am by you watching this I guess....am taking requests by subscribers...

[BriansBiology]

Glad to see this is helping people around the world...

[smoothieJu]

Now I think I got it, how it works:)

[corkygimpo]

excellent!!

[BriansBiology]

any requests for a new video?

[Luguirar]

Hello.

I can't understand how Okazaki Fragments occur. Can you help me?

[Loveable13e13e]

PCR and cellular respiration

[Loveable13e13e]

cellular respiration and photosynthesis

[benderquack]

@BriansBiology Great Video!! explained clearly!

Could you do a video for transcription and translation?? that would help me so much

[EduardoDRep]

Thank you sir. This really helped. :)

[veronicafayebaguio]

thank you sir ;D

[BriansBiology]

a pleasure to help.