What Are Antibiotics Made Of?


What are antibiotics made of?

Drew Smith:

Most antibiotics are based on natural products synthesized by bacteria and fungi. Quinolones (like Cipro) and sulfa drugs (like sulfamethoxazole) are the major exceptions to this rule.

Antibiotics belong to a class of natural compounds called secondary metabolites. These are molecules that are not essential to normal growth and metabolism (like sugars, amino acids, and nucleic acids) but perform specialized roles. Secondary metabolites enable creatures that can’t move or speak to communicate, control their environments and defend themselves.

Bacteria, plants, and fungi are much better than human chemists at creating complex molecules. These biosyntheses are often accomplished in factories within cells, large complexes of enzymes in which various precursors and intermediates are assembled, modified, and passed on.

Vancomycin, the most commonly prescribed antibiotic in U.S. hospitals, is a good example:

Although total synthesis of vancomycin has been accomplished in labs, I believe that it is still produced commercially by fermentation of the bacterium Amycolatopsis orientalis from which it was first isolated.

The thing to keep in mind about these secondary metabolites is that anything that is made by an enzyme can also be broken down by an enzyme—often the same one that made it. Small tweaks to these enzymes, or just putting them in a different environment, can cause them to degrade antibiotics. Antibiotic resistance is thus an intrinsic and inevitable feature of antibiotic use.

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What's the Difference Between Straw and Hay?


The words straw and hay are often used interchangeably, and it's easy to see why: They're both dry, grassy, and easy to find on farms in the fall. But the two terms actual describe different materials, and once you know what to look for, it's easy to tell the difference between them.

Hay refers to grasses and some legumes such as alfalfa that are grown for use as animal feed. The full plant is harvested—including the heads, leaves, and stems—dried, and typically stored in bales. Hay is what livestock like cattle eat when there isn't enough pasture to go around, or when the weather gets too cold for them to graze. The baled hay most non-farmers are familiar with is dry and yellow, but high-quality hay has more of a greenish hue.

The biggest difference between straw and hay is that straw is the byproduct of crops, not the crop itself. When a plant, such as wheat or barley, has been stripped of its seeds or grains, the stalk is sometimes saved and dried to make straw. This part of the plant is lacking in nutrients, which means it doesn't make great animal fodder. But farmers have found other uses for the material throughout history: It what's used to weave baskets, thatch roofs, and stuff mattresses.

Today, straw is commonly used to decorate pumpkin-picking farms. It's easy to identify (if it's being used in a way that would be wasteful if it were food, chances are it's straw), but even the farms themselves can confuse the two terms. Every hayride you've ever taken, for example, was most likely a straw-ride.

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How and Why Did Silent Letters Emerge in English?


Kory Stamper:

The easy answer is “"because English can’t leave well enough alone."

When we first started speaking English around 600 AD, it was totally phonetic: every letter had a sound, and we sounded every letter in a word. But English—and England itself—were influenced quite a bit by the French, who conquered the island in 1066 and held it for a long time. And then later by Dutch and Flemish printers, who were basically the main publishers in England for a solid two centuries, and then by further trading contact with just about every continent on the planet. And while we’re shaking hands and stealing language from every single people-group we meet, different parts of the language started changing at uneven rates.

By the 1400s, English started to lose its phonetic-ness: the way we articulated vowels in words like “loud” changed slowly but dramatically, and that had an effect on the rest of the word. (This is called “The Great Vowel Shift,” and it took place over a few hundred years.) Somewhere in the middle of the GVS, though, English spelling became fixed primarily because of the printing press and the easy distribution/availability of printed materials. In short: we have silent letters because the spelling of words stopped changing to match their pronunciations.

This post originally appeared on Quora. Click here to view.