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Sunday, June 11, 2017

Let's Make This Post go Chiral: From Amino Acids to Zwitterions

      A recent RadioLab story inspired this week's post on chirality; we certainly hope this Partial Ellipsis of the Sun post goes chiral





      Chirality is the property of having a structure that is non-superimposable on its mirror image. The term chirality is derived from the Greek word for hand, χειρ (kheir).




      The mirror images of a chiral molecule/ion are called enantiomers or optical isomers.



     Most DNA (B-DNA) double-helix molecules are right-handed, though there are some DNA molecules called Z-DNA that are left-handed. Thus, the labels on the following diagram are correct for most DNA.





     The chirality of molecules has much importance in biomolecules and in pharmaceuticals where left-handed molecules are more often the norm; the toxic version in right-handed molecules (like thalidomide) are the abnormal and destructive ones. Ironic that the handedness of molecules caused so much hand/arm (and foot/leg) deformities in thalidomide babies.



      On earth, amino acids characteristic of life are all left-handed in shape (Levo), and cannot be exchanged for their right-handed (Dextro) counterparts.  However, all sugars characteristic of life on Earth are right-handed, hence, dextrose. The opposite hands for both amino acids and sugars exist in the universe, but they just aren’t utilized by any known biological life form.




      A zwitterion is a neutral molecule with both positive and negative electrical charges. The image on the right (above) is a zwitterion.







     Thus, amino acids in earth's life forms go left, sugars go right, DNA double helixes go right. What's the Chirality Winner? ;-)

Please hand in your Chiral thoughts. . .
Steph

(And here's Telluride, CO, this weekend to clear your head and hands from all those chiral molecules):


31 comments:

  1. Chirality would be a good spelling bee word, or definition stumper on "Says You".

    This Smithsonian article goes into further depth about the study and implications of chirality (which begins at home, of course).

    I get a weird headache from left handed sugars. I can't rule out that it's psychosomatic, but I usually check labels, and only realize I've eaten Splenda or Aspertame after I get the headache.

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    1. Chirality is a delightful word.

      Thanks for the Smithsonian link, eco.

      And I can't handle the right-handed amino acids in Mono-Sodium Glutamate (as in I have not made it to the restaurant restroom when MSG was accidently in food).

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    2. I can't say thank you for sharing.

      Even in my more resilient 20's MSG gave me a kind of indescribably weird feeling all over, kind of like bugs crawling in my bloodstream. Fortunately most restaurants in the Bay Area either don't use MSG or offer food without. Though it sometimes seems to sneak in, especially in cheap Asian places.

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  2. Random thoughts:
    Paul Simon was nearly branded Communist because he was left-handed! I think Roy Cohn and Joe McCarthy, the senator from the great state of Wisconsin, might have been involved.

    A puzzle -maker's query: How would chirality, "the property of (being) a structure that is non-superimposable on its mirror image" apply to capital letters of our alphabet? R, Q and C have no chirality? A, W and O have a whole boatload of chirality?

    Forget chirality. What about Twitterion!... the non-neutral social media vehicle which in the hands of egomaniacal yet insecure twits manifests both unfounded and ad hominem negative and even more negative charges.

    LegoWhoThanksToStephAndPEOTSNowAbidethInFaithHopeChirality,TheseThree;ButTheGreatestOfTheseIsChirality

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  3. Hey Lego, R and Q are chiral, C is symmetric along a horizontal axis, A and W are symmetric along a vertical axis, and O, X, H and I are symmetric along both vertical and horizontal axes.

    It makes me think a "HI, OX" book would be good for new readers as none of those letters are chiral. It is easier to learn letters with one or two axes of symmetry, especially for anyone with dyslexia.

    Zwitterion makes me happy and Twitterion makes me smile :-).

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  4. Drawing Circles: Wonderful synchronicity to this week's PEOTS topic. Try your hand at drawing circles and check out the "C" worksheet. Do you remember completing early handwriting worksheets?

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    1. Handwriting? I print in block caps, and it's still barely legible. Cursive lasted only as long as it was required, from 3rd through 6th grades, at most.

      Drawing circles reminds me of Leo Rosten's probably apocryphal explanation for the ethnic slur, "kike". Illiterate Jewish immigrants at Ellis Island would refuse to sign their names with an "X", since it resembles a cross, and drew a circle instead (no report of how they drew circles). The Yiddish word "kikel" for "circle", became the derogatory term for the immigrants themselves. But, is "kikel" really Yiddish for "circle"? I'm skeptical.

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    2. Interesting. I did not know about the possible origin of the word kike. I don't see a Christian cross as much in "X" as I do in "t," though I do understand about the history of the Chi Rho , which sure sounds similar to "Chiral."

      All this O and X talk makes me ready for a game of Tic-Tac-Toe or Noughts and Crosses, using those two symmetric-along-at-least-two planes letters.

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    3. Reminds me of an assignment as a freshman: on an 18" x 12" piece of paper write a word, in cursive, backwards and forwards simultaneously with each hand (i.e. left hand writes it backwards, right hand writes it forwards), starting at a single point. And don't do this once, do it over and over, in neat rows and columns, to fill up the whole page, and don't write super large words, or use guidelines to make the words line up, it had to be by eyeball.

      I chose the word "line", and got a good grade not because I wrote it several hundred times, or that my rows and columns lined up reasonably well, but because they liked the proportion of the white space left in between where the words were written. The best grade went to a person who wrote "fun", because in cursive the "f" extends above and below the lines, and the spaces in between the lines were almost perfect squares.

      We were not told the criteria in advance, and we were all very cursive after this was done.

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    4. Very cursive--hahaha. Sounds scripted to me.

      "Line" seems easy and almost "fun."

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  5. Remember the Volkswagen Quantum? It never sold well, probably because most people didn't understand or didn't believe their Quantum Mechanics.

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    1. eco, quantum mechanics--bwahaha. . .

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    2. A favorite old bumper sticker:

      QUANTUM MECHANICS DO IT WITH UNCERTAINTY

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    3. Is quantum communication kind of like letting the cat out of the bag?

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    4. Schrödinger is smiling for sure, Paul.

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    5. Schrödinger always makes me think of Pat Schroeder, (D) Colorado House of Representatives from 1972-1997. In her memoir, 24 Years of House Work and the Place is Still a Mess, she mentioned Richard Nixon, who wore makeup all the time, by saying "I had an incredible urge to wash his face". Ah, history repeats itself. . .

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  6. The smell test: glad I can still smell perfumed people or smokers the minute they enter the swimming pool.

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  7. Glad you didn't post this three days ago when a rotten head cold/ flu wreaked havoc on my olfactory senses. But they're back, and I can tell the world still stinks.

    Would be nice to have an early, inexpensive indicator of potential Alzheimer's/ Parkinson's. I wonder if it would also apply to other neurological disorders, say Huntington's?

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  8. How can you resist a fruity headline like this?

    Grand Theft Avocado

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    Replies
    1. Did they need a major pit stop?

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    2. Surprisingly, not the first avocado theft story I've heard. I remembered hearing this one on the radio last year.

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  9. New post on "Celebrate Cephalopod Week: Squid, Octopuses, Cuttlefish, and Nautiluses" is now up.

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