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Close-Up View of DNA Replication
- YCode 9y agoI have no idea what I'm seeing here. I don't doubt what they are saying, but that looks nothing like the models of DNA that are used as eye candy in movies and such.
- tyingq 9y agoI assume the eye candy was an ultra sharp zoom into a single strand showing the double helix? This is zoomed out and fuzzy, such that you see a bunch of growing strands...not the detail of just one. And just as fuzzy white lines, given the relative size and techniques used to make it visible.
- pazimzadeh 9y agoHere's the original paper: https://www.pdf-archive.com/2017/06/20/piis0092867417306347/piis0092867417306347.pdf https://www.pdf-archive.com/2017/06/20/piis0092867417306347/...
- comatosesperrow 9y agoIt doesn't look like DNA models you are used to because a microscope that would give you that level of resolution does not exist. Even in the best images that exist, all you are going to see are little bits that look like string.
- YCode 9y agoI guess I'm just struggling to see how the animation maps to the DNA or how the scattering of dots becomes a double helix.
- hirundo 9y agoMost explicit porn ever!
- bwang29 9y agoI can feel there is something really interesting here but the writing, title and explanation here seems to be poor. The surprise here is the random starts and stops as well as 10X speed difference in the DNA replication process. Wouldn't it be more surprising that these processes run at the same speed? "...started watching individual DNA strands..." I'm wondering how important the visualization and nature of "filming" helped to form the idea or prove the hypothesis that replication is a async process. I didn't quite gather which is more impressive, the filming or the discovery. “Sometimes the traffic in the next lane is moving faster and passing you, and then you pass it. But if you travel far enough you get to the same place at the same time.” also doesn't quite make sense to me as the video clearly shows no queuing structure as seen in real life traffic, and there is no real hypothesis to explain the sudden stops and starts.
- ekianjo 9y ago> “We’ve shown that there is no coordination between synthesis of the two strands. They are completely autonomous,” Kowalczykowski said. Couldn't that be the unintended effect of doing things in a flow chamber?
- deleted 9y ago[deleted]
- darkkindness 9y ago> “It’s a real paradigm shift, and undermines a great deal of what’s in the textbooks,” he said. Sorry, but is this really that new? I've never been taught that the DNA strands coordinate with each other while replicating, so it seems quite possible that synthesis of each strand can be independent of each other.
- cjbprime 9y agoIt's a university press release. They're all written that way, unfortunately.
- deleted 9y ago[deleted]
- nerdponx 9y agoThe "paradigm shift" is referring to the "stochastic" nature of replication, which apparently was not known before.
- dekhn 9y agoi was taught all the things they're saying in this press release ~20 years ago in biochem class.
- alephnil 9y agoWhen I did my Phd in bioinformatics about 10 years ago, most of the molecular biologists and biochemists I talked with expected that something similar to what these researchers found was what happened, but the details was of cause not known. Thus this is maybe the least surprising result they could get. In Kuhnian terms, this is puzzle-solving rather than a paradigm shift.
- saagarjha 9y agoHmm…possibly there's some other process going on during those "slowdowns" that we haven't observed yet?
- deleted 9y ago[deleted]
- KasianFranks 9y agoI agree, that's part of the import here.
- deleted 9y ago[deleted]
- ekianjo 9y agoFor anyone interested in the molecular process of DNA replication, here's a pretty cool video that explains what happens at the protein level. It's always amazing to watch what is in practice a molecular-sized machine: https://www.youtube.com/watch?v=OjPcT1uUZiE https://www.youtube.com/watch?v=OjPcT1uUZiE
- haskman 9y agoThat was amazing! Especially the machinery of the second part where the DNA strand is replicated backwards!
- im3w1l 9y agoThat looks more error-prone, wonder if that copy has more mutations...
- ekianjo 9y agoyeah I am wondering if there is any research on that particular matter.
- Palomides 9y agoyes, e.g. [1], but there are specialized repair mechanisms that operate at the same time, so the 'final' error rate is much lower than the 'initial' rate. [1]: http://www.nature.com/nature/journal/v518/n7540/abs/nature14183.html http://www.nature.com/nature/journal/v518/n7540/abs/nature14...
- deleted 9y ago[deleted]
- pfd1986 9y agoHave a look at this lecture. It's really well explained, at a undergrad level, how the cell keeps the error rate low. Quite impressive, imo. https://youtu.be/DRBREvFL19g https://youtu.be/DRBREvFL19g
- rwmj 9y ago
- sidcool 9y agoThis is amazing. I can't wrap my head around the fact that some brilliant people discovered this long back. Scientists and Physicists are so talented! And I can't center a <div> without googling. Sigh...
- ValleyOfTheMtns 9y agoSomething I've never understood is how the nucleotides arrive to be included in the DNA strand. These animations always just show them appearing in perfect sequential order when they're needed, which is of course not what happens. How are they delivered to the polymerase in the first place? How do they "know" where to be? Are there just so many of them in the cytosol that through sheer numbers, there's enough random chance they'll just shuttle into place when the polymerase needs them?
- tsotnet 9y agoAs you said there are a lot of them, and they move randomly at crazy speeds (see Brownian Movement), accidentally coming together.
- fdej 9y agoYes, and indeed, this is why life as we know it only works in a narrow temperature range: high enough for Brownian motion to drive reactions, low enough not to unravel the results too quickly.
- dflock 9y ago> Are there just so many of them in the cytosol that through sheer numbers, there's enough random chance they'll just shuttle into place when the polymerase needs them? Yes. Everything at that scale is very small, very close together and moving very, very fast. This kind of thing is very common at the cellular level: have a receptor/channel/process/thing that only one precise 3d molecule can fit into - and then just wait. As long as there's a process somewhere to make/acquire that molecule, then one will be along in a few nanoseconds or so, depending on the concentration. In the meantime the recipient will just wait. In this way otherwise independent processes can regulate each other, and respond in a concentration dependant way to changing conditions without any central control.
- api 9y agoI always thought of it as a probability field of molecules.
- Angostura 9y agoI really appreciate science journalists who can explain accurately and clearly in this manner. Good job.
- cortic 9y ago- "Almost all life on earth is based on DNA being copied, or replicated" - Can anyone tell me what they are referring to here? (life on earth that isn't based on DNA)
- kittiepryde 9y agoRNA I believe. ( Which I only existed at one time, in theory? Or some people think viruses count as life )
- cortic 9y agoi did spend an embarrassing amount of time trying to find an example of RNA life after reading your initial reply lol. I suppose viruses do count as 'life' in some sense, so fair enough, thanks for clearing that up.
- dekhn 9y agoviruses don't count as life. they have no metabolism (but satisfy the other requirements).
- jcims 9y agoMy mind always boggles at the sophistication of this little machinery, and what forces drove random chemicals into the first primitive forms of encoding and reproducing heritable traits subject to selective pressure. The bootstrapping of evolution.
- inetknght 9y agoAs someone who works in the DNA analysis software industry... #neat
- Companion 9y agoNot sure if the apparent stop start observation, and also one strand sometimes getting synthesized while the other isn't would actually occur in-vivo. This is a pretty cool technology but a heavily artificial in-vitro system at the end of the day.