@beccalishass 5' end of the INCOMING dNTP has a good leaving group (PP). If you're going to join 5' to 3', that means the incoming dNTP has to add on to the 3' end of the existing strand.
also, if you would take a look at my other conclusion regarding the ribosomes, it would be great too. here goes,
Ribosomes read the mRNA from 5' to 3'. They do this by attaching to AUG on the 5' end of the mRNA molecule. They then read all the way till a stop codon is found. The Anticodon (on the tRNA) must be complementary to this, so it must be read from 3' to 5'. That is the anticodon for 5' AUG 3' is 3' UAC 5'.
@GJEViLakaTHEKING Yes, absolutely. Anticodons are the one exception to the rule that nucleic acid sequences are given 5' to 3' -- generally we state anticodon sequences 3' to 5', so we'd say the methionine anticodon (pairs with AUG) is UAC. Normally you'd say CAU, since that's 5' to 3', but it would be confusing to say it that way.
You Explain things like an amazing Boss. It would be great if my university hired you as a prof!
I always have a hard time understand with the directions, so THANKS!
in video's conclusion,
DNA polymerase reads the template strand from 5' to 3' direction, BUT adds the nucleotides to a open 3'OH group so it attaches from 3' to 5'. It makes the rna molecule starting at 3' towards 5'.
@GJEViLakaTHEKING -- I think you're misstating the conclusion. DNA polymerase (or RNA polymerase) moves along the template strand in the 3' to 5' direction (as seen from the template strand). The newly synthesized nucleic acid strand is antiparallel to that template, and is made by adding nucleoside triphophates to the 3' end of that new strand. Thus the new strand grows in the 5' to 3' direction. The 5' end of, for instance, an RNA molecule is made first; the 3' end is made last.
oh thats true, I think I just got very excited and wanted to type it all out fast!
So yea, the template strand is read from the 3' to the 5' direction. the dna polymerase (or rna polymerase) adds makes 5' to 3'. It does this by adding to the free 3' OH group.
The part that I don't understand is why 3' to 5' doesn't work. Specifically if DNA polymerase attempts to add a dNTP to the 5' end, why is the pyrophosphate leaving group already gone, since it wouldn't have been involved in the previous addition of a nucleotide to the 5' end of the chain.
@agathman In regards to why 3' to 5' addition of nucleotides isn't seen, only 5' to 3' replication allows efficient error correction. If the pyrophosphates are cleaved from the base already incorporated(as in 3' to 5'), if an an error is detected and the exonuclease removes one base, the phosphates required for the correct base to be added have already been cleaved away, they can not come from the new base.Thus further strand synthesis couldn't occur. So proofreading is likely a good reason too.
@Platypusti - In principle, it could work. The main problem is the inherent instability of the triphosphate. That's why it's reactive, right? If you're going to put that triphosphate on the 5' end of the primer, you're going to have to use that primer very soon, before the extra phosphates come off spontaneously. As far as I know, there's no example in nature of an organism doing it that way, but I'm not saying there couldn't be.
so in a nutshell, 5 prime end has a favourable leaving group (O) and therefore.........still a tad lost
beccalishass 3 days ago
@beccalishass 5' end of the INCOMING dNTP has a good leaving group (PP). If you're going to join 5' to 3', that means the incoming dNTP has to add on to the 3' end of the existing strand.
agathman 3 days ago
Thank you so much! My professor neglected to draw out the structures for why 3`-->5` wouldn't work so it was very confusing!
moonshadow285 1 month ago
Thanks a lot for your video, it is clear to me now!
Haatpiraat 2 months ago
Do you teach microbiology too? (I would commute, from WA) Your lecture style is so clear to me, thank you for posting these videos.
bluskish 3 months ago
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Thank to you for your teaching it's very brilliant and great i can understand this i said onemore time thank you very much Mr.Agathman
Ranjithlove1992 3 months ago
Thank to you for your teaching it's very brilliant and great i can understand this i said onemore time thank you very much Mr.Agathman
Ranjithlove1992 3 months ago
Excellent explanation Sir! Only wish the video quality was abit better...
TheShikobe 3 months ago
This video is by far the most amazing video on DNA replication I have ever seen. Everything makes sense now. Thanks you so much!
VashaB 4 months ago
also, if you would take a look at my other conclusion regarding the ribosomes, it would be great too. here goes,
Ribosomes read the mRNA from 5' to 3'. They do this by attaching to AUG on the 5' end of the mRNA molecule. They then read all the way till a stop codon is found. The Anticodon (on the tRNA) must be complementary to this, so it must be read from 3' to 5'. That is the anticodon for 5' AUG 3' is 3' UAC 5'.
GJEViLakaTHEKING 4 months ago
@GJEViLakaTHEKING Yes, absolutely. Anticodons are the one exception to the rule that nucleic acid sequences are given 5' to 3' -- generally we state anticodon sequences 3' to 5', so we'd say the methionine anticodon (pairs with AUG) is UAC. Normally you'd say CAU, since that's 5' to 3', but it would be confusing to say it that way.
agathman 4 months ago
@agathman Much thanks!
GJEViLakaTHEKING 4 months ago
You Explain things like an amazing Boss. It would be great if my university hired you as a prof!
I always have a hard time understand with the directions, so THANKS!
in video's conclusion,
DNA polymerase reads the template strand from 5' to 3' direction, BUT adds the nucleotides to a open 3'OH group so it attaches from 3' to 5'. It makes the rna molecule starting at 3' towards 5'.
the same is true for rna polymerase (I think)
GJEViLakaTHEKING 4 months ago
@GJEViLakaTHEKING -- I think you're misstating the conclusion. DNA polymerase (or RNA polymerase) moves along the template strand in the 3' to 5' direction (as seen from the template strand). The newly synthesized nucleic acid strand is antiparallel to that template, and is made by adding nucleoside triphophates to the 3' end of that new strand. Thus the new strand grows in the 5' to 3' direction. The 5' end of, for instance, an RNA molecule is made first; the 3' end is made last.
agathman 4 months ago
@agathman
oh thats true, I think I just got very excited and wanted to type it all out fast!
So yea, the template strand is read from the 3' to the 5' direction. the dna polymerase (or rna polymerase) adds makes 5' to 3'. It does this by adding to the free 3' OH group.
GJEViLakaTHEKING 4 months ago
It is a honor listening to you sir, such a great way of explaining. Thank you.
qrais 4 months ago
enlightening!
egglot12 4 months ago
Reasonable and nice illustration!
fallingleaver 5 months ago
The part that I don't understand is why 3' to 5' doesn't work. Specifically if DNA polymerase attempts to add a dNTP to the 5' end, why is the pyrophosphate leaving group already gone, since it wouldn't have been involved in the previous addition of a nucleotide to the 5' end of the chain.
davebunnell1 10 months ago
@davebunnell1 See the response below to Platypusti.
agathman 10 months ago
@agathman In regards to why 3' to 5' addition of nucleotides isn't seen, only 5' to 3' replication allows efficient error correction. If the pyrophosphates are cleaved from the base already incorporated(as in 3' to 5'), if an an error is detected and the exonuclease removes one base, the phosphates required for the correct base to be added have already been cleaved away, they can not come from the new base.Thus further strand synthesis couldn't occur. So proofreading is likely a good reason too.
Oneironosus 3 months ago
Comment removed
davebunnell1 10 months ago
This was amazing, thank you very much for this awesomely visual explanation.
xkurtmanx 11 months ago
So isn't it possible to create a primer with 3 phosphates on the 5' end? (Through mutation perhaps) If so would that work?
It was really helpful though.
Platypusti 1 year ago
@Platypusti - In principle, it could work. The main problem is the inherent instability of the triphosphate. That's why it's reactive, right? If you're going to put that triphosphate on the 5' end of the primer, you're going to have to use that primer very soon, before the extra phosphates come off spontaneously. As far as I know, there's no example in nature of an organism doing it that way, but I'm not saying there couldn't be.
agathman 1 year ago
great vid, nicely explained.
BeastLazy 1 year ago
Great video explanation! My first med school exam is tomorrow and this was one of the questions the professor asked us to know for the exam.
bigblueltz71 1 year ago