How Does Protein Get Made?

by Farkel 4 Replies latest jw friends

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  Farkel

  Not being a science guy (my "higher education" came from being a pioneer and reading countless piles of Awake! shit) I have a question for you bio-chemists out there:

  I recently heard this syllogism:

  Assertion: "Humans who eat meat claim that they get their best source of protein from eating animals like cattle."

  Assertion: "Cattle are a source of protein, and all they eat is vegetation."

  Conclusion: "Vegetation provides all the protein we need. Cattle meat is merely the provider of that original protein that first came from plants."

  I was a lacto-ovarian vegetarian (being a true vegan was just too much to ask of me: I still ate milk products, eggs and fish) for three-and-a-half years but went back to being a meat-eater for two reasons:

  1) My former wife and I decided that by becoming vegetarians we did not have the right to impose the same on our children, and so gave them the choice of joining us, or not. They said "NO!" They wanted MEAT! She therefore had to cook TWO separate meals each evening for us all. The veggie meals got boring and she lost interest in being creative about the food she was offering for the two of us, so we both went back to the horrors of prime rib, rib-eyes, pork loins and other terrible foods.

  2) I came to realize that my ancestors didn't fight long and hard for people like me to rise to the top of the food-chain to eat stuff at the BOTTOM of the food-chain! (Tongue-in-cheek, here!)

  I've heard arguments about vegetables being "incomplete" protein, whereas meat is "complete" protein and I've heard counter-arguments about that, too.

  While I'm waiting for you chemists to enlighten me, I think I'll chaw on a hunk of meat from a deal animal.

  In short my question is: "Can a plant which might not contain protein, be converted to protein in an animal which is in fact a source of protein?" If so, how does protein get created then?

  Farkel, the curious
  "Shakin' the Bush, Boss. Shakin' the Bush" Class
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  Thirdson

  All life contains protein (plants, animals, bacteria). Proteins are long chains of amino acids and serve multiple purposes. We think about muscle as being protein but enzymes, antibodies, hormones, hemaglobin and ferrtin (iron storage) are all sorts of proteins. When it comes to meat and plants, plants contain a lot more structure in the form of things that we (humans) can't digest such as cellulose.

  When it comes to obtaining protein, think about how much grass a cow eats in the course of maturity. We can't eat grass because we don't have multi-chamber stomachs. We can simply acquire the protein from meat by eating beef. However, during digestion protein, from whatever source, is broken back down into amino acids to be reassembled in opur own cells for our own use.

  Does any of that help?

  Thirdson

  'To avoid criticism, say nothing, do nothing, be nothing'
• 

  TD

  Farkel,

  Briefly, the digestive system breaks the food you eat down into soluable materials that can pass through the cell membrane – simple sugars, fatty acids, amino acids, trace elements and water.

  Proteins are essentially long chains of amino acids assembled within the cell in various combinations. Insulin for example is formed from 16 different amino acids. Some proteins are long, thin fibers, such as those of hair or silk while others are “folded” into three-dimensional shapes like hemoglobin and other blood proteins.

  The source of the protein consumed is not particularly relevant as it all gets broken down into its constituent amino acids anyway. Problems arise when one is restricted to a diet deficient in one or more essentialamino acids.

  Strict vegens need to give special attention to their diet for the simple reason that plant tissue generally contains much less protein than does animal tissue. A pound of hamburger contains 107 grams of protein whereas a pound of potatoes contains only 10. With the proper diet, vegetarianism can be a perfectly healthy lifestyle though.
• 

  terraly

  So, our bodies actually need the amino acids from proteins. There's like 20 odd amino acids, and our bodies are incapable of producing some of them (I don't remember how many). These we need to get from our diet.

  Vegetables contain plenty of proteins supplying these amino acids. However, as Thirdson points out, some of the best sources are digestively unavailable to us. Others, nuts and beans for example, contribute many of the necessary amino acids, but not all of them

  In some sense then, meat is a "superior" protein. Many forms of meat have the full range of necessary amino acids, which make them an easy way to get a full complement. However, some vegetables do too (notably spinach and soy), and in general protein derived from plants will provide you with the full necessary range, as long as you eat at least a small variety of different protein sources.

  So in answer to your syllogism:
  Where does the protein come from in the plants in the first place? Answer: they are able to make the component amino acids (they're just simple molecules made up only of C,H,O, and N) and stick them together (in fact, amino acids can also be made in interstellar space, but that's another fascinating tale*).
  Cows can do the same thing, and so can humans, but we can't make all of the ones we need, so we have to capture some intact, and meat is a good way to capture them all at once.

  * As a matter of act, you can get chiral** amino acids in outer space, which is a pretty cool and amazing fact.

  ** chiral refers to the "handed-ness" of something. Basically, your hands are exactly the same shape, but they're not the same, ie, you can't exactly superimpose one on top of the other. The same thing happens with the geometry of some molecules. Now, the cool thing is that most processes are achiral, making the same amount of "left" and "right" molecules. However, biology is often chiral- we only have "left-handed" kinds of some molecules. For this reason, scientists sometimes assumed that a chiral signal indicated life.

  A recent result by Pizzarello and Cronin showed that interstellar dust is chiral in at least one amino acid (2-amino-2-methyl-butanoic acid). That is, some process is causing one "hand" of this molecule to be preferentially created or destroyed. That process is unknown (although there are some guesses).
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  terraly

  duplicate post deleted