DNA replication – 3D

DNA replication – 3D

DNA is a molecule made up of two strands twisted around each other in a double
helix shape. Each strand is made up a sequence of four chemical bases represented by the letters A, C, G and T. The two strands are complementary. This means that wherever there’s a T
in one strand there will be in an A in the opposite strand, and wherever there’s a C there will be a G in the other strand. Each strand has a 5′ end and a 3′ end. The two strands run in opposite
directions. This determines how each strand of DNA is replicated. The first step in DNA replication is to separate the two strands. This unzipping is done by an enzyme
called helicase and results in the formation of a
replication fork. The separated strands each provide a
template for creating a new strand of DNA. An enzyme called primase starts the
process. This enzyme makes a small piece of RNA called a primer. This marks the starting point for the
construction of the new strand of DNA. An enzyme called DNA polymerase binds to the primer and will make the new strand of DNA. DNA polymerase can only add DNA bases in one direction, from the 5′ end to the 3′ end. One of the new strands of DNA, the leading strand, is made continuously, the DNA polymerase adding bases one by one in the 5′ to 3′ direction. The other strand, the lagging strand,
cannot be made in this continuous way because it runs in the opposite
direction the DNA polymerase can therefore only
make this strand in a series of small chunks called Okazaki fragments. Each fragment is started with an RNA primer. DNA polymerase then adds a short row of
DNA bases in the 5′ to 3′ direction. The next primer is then added further
down the lagging strand. Another Okazaki fragment is then made and the process is repeated again. Once the new DNA has been made the enzyme exonuclease removes all
the RNA primers from both strands of DNA. Another DNA polymerase enzyme then fills in the gaps that are left behind with DNA. Finally the enzyme DNA ligase seals
up the fragments of DNA in both strands to form a continuous
double strand. DNA replication is described as semi-
conservative because each DNA molecule is made up
of one old, conserved strand of DNA and one new one.

100 Replies to “DNA replication – 3D

  1. It is so amazing that this complex machinery of information (Here, DNA) replication has to take place without error that too at the rate of 2000 base pairs per second! Just imagine having to do it artificially on a system would be so expensive and time-consuming!

  2. Omg I love you so freackin much. German channels can‘t explain shit even though I watched 10000 Clips about DNA-Replication. So much love♥️♥️♥️😩😭

  3. Lot of stuff is missing in the video , The A proteins unbind the DNA double helix , The SSB prevent em from binding each other , replication bubble is formed thus . Them Helicase unwinds the DNA and topoisomerase helps in preventing torsional strain due to Helicase effect . 2 Replication Fork are formed , one on each side , Then comes the primase , forms the complex with Helicase called Primosome . Primase syn primmer ( short chain RNA molecula) , DNA polymerase starts Nacent Daughter strand syn on leading strand in 5-3 prime direction , the lagging strand DNA is syn in short fragments (Okazaki)
    After completion one Okazaki frag , primase is released and new primer is syn .. after completion of process primase is removed from DNA hybridase
    Gap removed after removal of prime is filled by nucleotides by complementary Basepaing I.e Okazaki acts as a fragment
    DNA ligase then seals the nicks req ATP
    Pray for my good grades my exam is on 16

  4. Orientation of leading and lagging is wrong..
    3'-5' will be leading and lagging will be 5'-3'..Opposite is shown here in this video.

  5. This doesn't actually explain why each protein moves, or where the proteins and RNA and DNA fragments actually come from.

  6. This is sooooo amazing with 3d visualisation I have chills when watching this… Gonna watch 9-10 times probably to remember it better…

  7. I’m French and I’ve understood it better in English because professors or unable to EXPLAIN IT CLEARLY IN A SIMPLE WAY !

  8. The leading strand is continuous and the lagging strand is discontinuous . The okazaki fragments have gaps in between them. Please ensure that. The video was amazing!👍

  9. People comparing their teachers to a video like dude its animation…how do u expect a teacher to explaim a 3d model like tht on board. They tried their best

  10. This is a brilliant design. Any good computer engineer will agree. It’s also not the product of random chemical processes. First, it’s far too complex and elegant to be the result of random processes. And second, if it were, it would have a lot of useless steps and could easily be improved upon and optimized. We’re still just beginning to understand it. Cells are actually teaching us about microbiology. We would not have even thought of such beautiful and complex things.

    And in addition to the complexity of these designs, there’s the fact that functional proteins are extremely specific arrangements of amino acids. The probability of even one functional protein forming by random processes is 1 in 10^77. But when you consider that functional proteins are homochiral, meaning that only L-handed amino acids can used, the mystery of their existence becomes very great.

    And the simplest cells need something like 150 different functional proteins, each in sufficient quantities. And they all would have to come together at the same time and microscopic location. But even having them all doesn’t produce life. They have to be arranged properly to do anything useful, and then who knows what then makes them “alive”?

  11. I wish this video mentioned when DNA polymerase I and III were being used. I believe III does the replication and I does strand checking/fragment removal?

  12. Easily the best replication video I've seen to date, thank you. I don't understand why it's so difficult for professors to explain this in a simple step by step process. I get that it's a complex topic, but damn, just go step by step. Stop talking about random enzymes in no discernible order.

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