DNA Replication

AvgJim: Yes, msc0328 explained me a lot of things about that. I looked at wikipedia after that, it seems that the way genes are active or not is rather complicated, and not completely understood? (for the moment). Are you working on biology?

Histones aren't "replicated". Quite interestingly enough they are the most conserved protein structure across all species.

Thanks for the answer. It is not exactly what I was trying to understand. But since it is going to be a little bit technical, I am going to answer you in your YouTube mailbox.

Histones are proteins that are made from transcription and translation of histone-coding genes. Before replication, lots of these histones are around so that when replication occurs, these histones slip neatly into place with the nascent DNA strands. During active replication, you won't find transcription occuring, as the physical space is occupied by the replication machinery. Make sense?

I can't stop looking at this video, this is awesome. DNA dancing... But I wonder how histones are duplicated: it is important to keep the information about which genes are active and which ones are inhibited. I didn't find in the Internet. Does anybody know?

I am going to go and see. Science is so fantastic! I don't understand why religious people can prefer their boring Magic Man...

Wikipedia can definitely be a great starting resource. Nature is incredibly clever and resourceful ... it's thought that DNA replication took over from an RNA based world sometime in the distant past (early cells, ~1 bya). We're not sure about what was before RNA ... google search Robert Hazen - he does fantastic pioneering work on abiogenesis and has a theory where clay crystals were the first replicator ... amazing!

Thanks for your reply! Indeed I saw that (the 3' and 5' stuff) in Wikipedia (how could have we lived without Wikipedia!) after my messages. Very interesting. And this kind of animation is awesome to understand how it works.

Nature is very clever to have invented this machine. Do we know how evolution created it? I thought that DNA replication was relatively simple, but it is not! (I say that because I am also interested in abiogenesis and evolution.)

fragments.

So a single double stranded molecule is made of two complementary strands that sit ANTI-PARALLEL to one another. This means that one half of the DNA runs 5'-3' and the other is attached to it 3'-5'. The big important fact here is that DNA can only be chemically synthesize from 5' to 3'! So if you unwind the double stranded DNA and move in one direction, only one strand allows you to make DNA from 5' to 3', the other one would have to be made 'backwards' which is what happens for okazaki

Very keen observations! Though your answer is chemically complex. Remember, DNA is DOUBLE-STRANDED. So, your letter analogy is hard to use. The real answer is that the chemicals that make one half of the strand have a particular direction called 5' and another one called 3' (the apostrophe is referred to as 'prime' - you actually say "five prime" and "three prime" as the ends).

Mmm... actually I said a stupidity, forget that message: the copy is correct. Just the *order* the nucleotides are copied is different, but they remain the same nucleotides since that strand remains as it is.

Strange why it is copied that order. I see that it is called "Okazaki fragments". I am going to read a little more about it...

I thought a lot about that but I really don't understand why one strand of the initial DNA should be copied backwards. These strands are symmetric: which one is supposed to be replicated in normal order and which one in the reverse order?

This second resulting strand is not a copy at all of the initial DNA! If the initial DNA is "abcdef", and we consider copy by group of 3 (to simplify) the result is something like "defabc" which is neither the normal nor the reverse DNA!

Lol him name :) lol meant to say his, but that's wrong also it's an it lol

That's so crazy evolution works wonders. It's like a biochemical machine. There is a creator and him name is nature :)