Mechanism of DNA Replication (Advanced)
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Knowing the structure of DNA, scientists speculated and then proved that DNA is the template for copying the genetic code. See how information in DNA is copied to make new DNA molecules. Originally created for DNA Interactive ( http://www.dnai.org ). TRANSCRIPT: During DNA replication, both strands of the double helix act as templates for the formation of new DNA molecules. Copying occurs at a localized region called the replication fork, which is a Y shaped structure where new DNA strands are synthesised by a multi-enzyme complex. Here the DNA to be copied enters the complex from the left. One new strand is leaving at the top of frame and the other new strand is leaving at bottom. The first step in DNA replication is the separation of the two strands by an enzyme called helicase. This spins the incoming DNA to unravel it: at ten thousand RPM in the case of bacterial systems. The separated strands are called three prime and five prime, distinguished by the direction in which their component nucleotides join up. . The 3' DNA strand, also known as the leading strand, is diverted to a DNA polymerase and is used as a continuous template for the synthesis of the first daughter DNA helix. The other half of the DNA double helix, known as the lagging strand, has the opposite 3' to 5' orientation and consequently requires a more complicated copying mechanism. As it emerges from the helicase, the lagging strand is organised into sections called Okazaki fragments. These are then presented to a second DNA polymerase enzyme in the preferred 5' to 3' orientation. These sections are then effectively synthesised backwards. When the copying is complete, the finished section is released and the next loop is drawn back for replication. Intricate as this mechanism appears, numerous components have been deliberately left out to avoid complete confusion. The exposed strands of single DNA are covered by protective binding proteins. And in some systems, multiple Okazaki fragments may be present. The molecular reality is very different from the iconic image of the double helix neatly separating into two DNA copies as so often depicted.
Comments
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jesus christ
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MISTAKE: it is stated that the lagging strand runs 3' > 5' when it DOESNT (it runs 5' > 3')
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2:05 But I WANT to see all the components. Although histones and SSB's etc. would be distracting, it would still improve our understanding. You could then make every unnecessary complex transparent, to show the repliosome in a more clear way.
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How did this evolve?
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an interesting information, thank u .
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an interesting information, thank u .
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Thank you for this! Quite hard to find animations, where the whole polymerase complex with sliding clamp and clamp loader and the formation of the loop is shown.
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this is the stuff i trip on acid
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Definitely not an advanced video of replication. Came here for B-clamp and clamp loader mechanisms and was disapointed. They show it in the video and don't explain. -.-
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Is this what they call "the trombone model"?
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why isn't there a good video about sliding clamp??
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Advanced?!?! Ha!
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hey are the lessons in order for what i need for the gre bio test? or do i need to choose what to watch next?! thenkyou
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This video is light years from being advanced.
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"Intricate as this mechanism appears, multiple components have been left out to avoid complete confusion..."
Lol. -
What is the green molecule?
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Now we need a complete version that leaves nothing out!
Because this was a bit too dumbed-down to serve for more than one watching.
How about a WebGL site where you can switch parts on and off, rotate it, slow it down, zoom, etc? -
this is frckn awesome, so neat and cool and logic, incredible animation, i guess it's slower than real time, real time is ~ 745 nucleotides per second from what wikipedia says
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This is a gorgeous animation. One of the best I've seen. No, the best.
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+FATgreyPLUM Atoms are only affected by the laws of physics, they do not know something called natural selection, and they cannot arrange themselves like this no matter how much you left them, algorithms are not produced by luck, the only things that we know it can produce algorithms is intelligence, and those in the video are very complicated algorithms.
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