TABan Posted October 21, 2015 Share Posted October 21, 2015 There's something scientifically inaccurate on the Alamy front page image featuring the two scientists and DNA molecule. Can anyone guess what it is? Link to comment Share on other sites More sharing options...
TABan Posted October 21, 2015 Author Share Posted October 21, 2015 There's something scientifically inaccurate on the Alamy front page image featuring the two scientists and DNA molecule. Can anyone guess what it is? Sure! Even a 5-year-old Belgian could see it: There's a mismatch in the DNA-dependent DNA polymerases which make copies of DNA polynucleotide chains. A 3′ to 5′ exonuclease activity is activated and the incorrect base removed which now functions in a large complex called the replisome that contains multiple accessory subunits, such as the DNA clamp or helicases. Another flaw are the Nucleases which are enzymes that cut DNA strands by catalyzing the hydrolysis of the phosphodiester bonds. And last but not least, the chemical modifications of these basic amino acid residues include methylation, phosphorylation and acetylation. Cheers, Philippe It's way simpler than that.Hint, DNA polymerase wouldn't ever encounter DNA as pictured. Link to comment Share on other sites More sharing options...
TABan Posted October 21, 2015 Author Share Posted October 21, 2015 There's something scientifically inaccurate on the Alamy front page image featuring the two scientists and DNA molecule. Can anyone guess what it is? Sure! Even a 5-year-old Belgian could see it:There's a mismatch in the DNA-dependent DNA polymerases which make copies of DNA polynucleotide chains. A 3′ to 5′ exonuclease activity is activated and the incorrect base removed which now functions in a large complex called the replisome that contains multiple accessory subunits, such as the DNA clamp or helicases. Another flaw are the Nucleases which are enzymes that cut DNA strands by catalyzing the hydrolysis of the phosphodiester bonds. And last but not least, the chemical modifications of these basic amino acid residues include methylation, phosphorylation and acetylation.Cheers,Philippe It's way simpler than that.Hint, DNA polymerase wouldn't ever encounter DNA as pictured. He forgot to add the unit formulae of each base, just substracted PO3H (because there is no phosphate linkage at the 3′-end), and added H2 (because both 3′-end and the 5′-end are protonated) to give the formula of the oligonucleotide C[/size]39[/size]H[/size]47[/size]O[/size]22[/size]N[/size]15[/size]P[/size]3[/size]-[/size]Cheers,Philippe I think you're just being silly. Come on, you know the answer, RIGHT? Link to comment Share on other sites More sharing options...
punkmuffin Posted October 21, 2015 Share Posted October 21, 2015 No Idea Link to comment Share on other sites More sharing options...
John Richmond Posted October 21, 2015 Share Posted October 21, 2015 The helix is clockwise, rather than anti-clockwise. Mind you, my biochemistry is 40+ years out of date so I could well be wrong. Link to comment Share on other sites More sharing options...
TABan Posted October 21, 2015 Author Share Posted October 21, 2015 Bingo. John's the smartest boy in class. Yes, B-DNA, which the form pictured, has a right-handed helix. In other words, if you look along the molecule, it twists to the right, or clockwise. The model in the photo has a left-handed helix. There is a left-handed form of DNA, called Z-DNA, but the two sugar-phosphate backbones have a zig-zag to them, they're not smooth like in the model. The front page image could still be used if flipped to a mirror image, although it's still not quite accurate as far as B-DNA's structure goes. Here's an illustration on Wikipedia of the three forms of DNA: https://en.wikipedia.org/wiki/Z-DNA#/media/File:A-DNA,_B-DNA_and_Z-DNA.png In the '90s, I was a photo researcher for Custom Medical Stock Photo (which has, unfortunately, closed its doors). We had a local illustrator I had to explain this to as she came in with a wonderful illustration of B-DNA and how it's packed into a chromosome but she drew a left-handed helix. It was an easy fix, we just made a master duplicate transparency and then flipped it for all subsequent dupes. We had to crop out her signature for obvious reasons. I'm not the only one with this pet peeve: http://users.fred.net/tds//leftdna/ Link to comment Share on other sites More sharing options...
TABan Posted October 21, 2015 Author Share Posted October 21, 2015 Are you by any chance family of Sheldon Cooper? Cheers, Philippe Just kidding Sheldon is on the spectrum. I'm closer to Leonard. I did photograph Martin Cooper once. And I was business acquaintances with Johnny Galecki's mother Lou a couple decades ago. Link to comment Share on other sites More sharing options...
John Richmond Posted October 21, 2015 Share Posted October 21, 2015 Bingo. John's the smartest boy in class. Finally, recognition of my genius. Though my wife might have different thoughts. Link to comment Share on other sites More sharing options...
Robert Brook Posted October 21, 2015 Share Posted October 21, 2015 Thanks. I couldn't see anything wrong with it, although I know the cytosine isn't dayglow green, and nor is guanine the same colour as Kylie's handbag. They never seem to explain that in kids' science books. I was puzzled by the researchers' look of near consternation. You never have worried looking people in commercial shoots (well bit of a shoot plus a bit of cgi) unless something is really wrong. I thought it definitely has a sci-fi look about it (Rosewell - The UFO Cover-up). Or even Solaris (the Russian version), although in that film the only females are made of neutrinos (but they are sad). So, that the only thing wrong with it is that the helix is the wrong way round (both of them) came as a great disappointment. However, thanks anyway - for me, one of the most useful posts for a while. My next project is on DNA. It would be so easy to spend half a week constructing a great model, only to find I had constructed it the wrong way round. Happens all the time. Link to comment Share on other sites More sharing options...
TABan Posted October 22, 2015 Author Share Posted October 22, 2015 Thanks. I couldn't see anything wrong with it, although I know the cytosine isn't dayglow green, and nor is guanine the same colour as Kylie's handbag. They never seem to explain that in kids' science books. I was puzzled by the researchers' look of near consternation. You never have worried looking people in commercial shoots (well bit of a shoot plus a bit of cgi) unless something is really wrong. I thought it definitely has a sci-fi look about it (Rosewell - The UFO Cover-up). Or even Solaris (the Russian version), although in that film the only females are made of neutrinos (but they are sad). So, that the only thing wrong with it is that the helix is the wrong way round (both of them) came as a great disappointment. However, thanks anyway - for me, one of the most useful posts for a while. My next project is on DNA. It would be so easy to spend half a week constructing a great model, only to find I had constructed it the wrong way round. Happens all the time. Glad it's useful! You'll share the model with us when complete? Link to comment Share on other sites More sharing options...
Robert Brook Posted October 22, 2015 Share Posted October 22, 2015 Thanks. I couldn't see anything wrong with it, although I know the cytosine isn't dayglow green, and nor is guanine the same colour as Kylie's handbag. They never seem to explain that in kids' science books. I was puzzled by the researchers' look of near consternation. You never have worried looking people in commercial shoots (well bit of a shoot plus a bit of cgi) unless something is really wrong. I thought it definitely has a sci-fi look about it (Rosewell - The UFO Cover-up). Or even Solaris (the Russian version), although in that film the only females are made of neutrinos (but they are sad). So, that the only thing wrong with it is that the helix is the wrong way round (both of them) came as a great disappointment. However, thanks anyway - for me, one of the most useful posts for a while. My next project is on DNA. It would be so easy to spend half a week constructing a great model, only to find I had constructed it the wrong way round. Happens all the time. Glad it's useful! You'll share the model with us when complete? If images are distributed to Alamy - depends whether it is RM or RF. Only RF get sent here - usually a month after it is first up. Like this: http://tinyurl.com/odqpp3l Link to comment Share on other sites More sharing options...
Guest Posted October 22, 2015 Share Posted October 22, 2015 Sans Blender or other CGI, there's always a quick way https://www.indigo.com/molecular_models/dna-rna/#.Vii96Wsvm8g Link to comment Share on other sites More sharing options...
Robert Brook Posted October 22, 2015 Share Posted October 22, 2015 Sans Blender or other CGI, there's always a quick way https://www.indigo.com/molecular_models/dna-rna/#.Vii96Wsvm8g Avec Blender but sans coloured beads. And tres realiste! Link to comment Share on other sites More sharing options...
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