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Wikipedia:Featured picture candidates/Cell membrane (diagrammatic)

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Cell membrane (diagrammatic)

edit
 
Original - The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes.
 
Edited
 
Edit 2 (Dhatfield)
 
Edit 3 (Dhatfield)
Reason
adding value to article and other reasons as given in typical animal cell
Articles this image appears in
Cell membrane, Lipid bilayer
Creator
Mariana Ruiz


  • Support as nominator --Alokprasad84 (talk) 08:06, 12 June 2008 (UTC)[reply]
  • Comment Perfectionism alert. This is technically above average and a lot of work has clearly gone in, but the layout is cramped and confusing. Technical One of your cholesterol molecules projects into a protein. Are the glycolipids at the bottom (dark green) different from the top ones? (My school biology is very rusty). Is the glycoprotein also a type of globular protein? I know it's a pain, but it would be better if your helix overlapped correctly. None of the alpha-helices other than the front one has a coil showing, making their type ambiguous. Your 'phospholipid molecule' is at an odd angle, seemingly projecting into the plane of the image - you could move it out to the side. Layout Overall, the third dimension is adding confusion (and not much else). For example the 'phospholipid bilayer' could refer to the height or depth dimension (corner to corner is the only dimension that fits visually). The dimension line should not be at an angle. It may be better to stick to Transport, Integral, Globular, Peripheral and Surface proteins (or similar classification) in the image and make finer distinctions in the text. Two diagrams, one showing bilayer detail with a monolayer in the third dimension and another showing the bilayer as a 3D 'layer' with filaments, cytoplasm, and clear intracellular / extracellular separation would have improved my comprehension when I was doing biology. Dhatfield (talk) 16:55, 12 June 2008 (UTC)[reply]
    • Response to technical concerns. Cholesterol can bind to proteins covalently (e.g. hedgehog protein). Each leaflet can have a different glycolipid composition, as well as phospholipid composition (see Flippase). A large fraction of membrane proteins are glycoproteins, globular or no. Agree re the helix looking clunky, but overall it looks technically good to me, though it might be nice to show more features, such as lipid rafts. de Bivort 21:14, 12 June 2008 (UTC)[reply]
  • Should we assume that a student knows about covalent cholesterol - protein bonding and variable leaflet lipid composition before looking at this image and therefore understands all of its nuances? In my opinion if it is impossible to tell whether there is bonding (never mind a change in protein composition), or if the author just accidentally overlapped the two, there's something wrong with the image. Same argument holds for the glycoproteins. Dhatfield (talk) 00:42, 13 June 2008 (UTC)[reply]
  • Made a new version to address my main objections. Still needs minor work on colours, layout, spacing, alignment, overlap of proteins. Since the source is in question (and therefore all derivatives), I am going to hold on working on this further until status is clarified. Dhatfield (talk) 14:48, 13 June 2008 (UTC)[reply]
  • Suspend Not sure what a 'traditional zoom box' looks like, an example would be very useful. None the less, I am suspending work and think that the candidate should be suspended. Until I see evidence to the contrary I will assume that in matters of copyleft on WP one is guilty until proven innocent. Dhatfield (talk) 09:34, 14 June 2008 (UTC)[reply]
  • Edit 3 uploaded Standard zoom boxes tend to obscure the labels, but if there is a consensus to change to those, I'll give it another try. Dhatfield (talk) 20:29, 16 June 2008 (UTC)[reply]
  • Strong oppose There are only unsaturated tails on the phospholipids, for a reduced structure diagram of a cell membrane's lipid bilayer there should be one unsaturated and one saturated tail on each phospholipid. Also, they're usually shown kinking outward, not inward. --Blechnic (talk) 05:05, 17 June 2008 (UTC)[reply]
I'm confused about what we're voting on now. Is it Edit 3 that is being considered? Then my comment goes to the phospholipids on the lower left--although often shown like this in illustrations, they should be shown with the unsaturated fatty acid tail kinked and making space, like the cholesterol, while the saturated fatty acid tail allows for close packing. Also the cholesterol appears to have a hydrophilic head, it should just be a cholesterol, you could bring it forward, or make it higher with that head missing. The hydrophobic tail label appears to apply only to the unsaturated fatty acid, it should apply to both fatty acids, and probably you could label by running a line right below the glycerol to make it clear that hydrophobic tail is both fatty acids. --Blechnic (talk) 23:16, 17 June 2008 (UTC)[reply]

Not promoted . --John254 01:54, 18 June 2008 (UTC)[reply]

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