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Al Stahler: Playing with building blocks

Al Stahler
Columnist

Doing chemistry is like playing with kids’ plastic building blocks. You take little blocks (chemists call their tiny blocks “atoms”) and stick them together to make sculptures (chemists call their sculptures “molecules”).

Atoms are like building blocks with rules:

Four white blocks stick to one black block, but only two white blocks can stick to a red, and those two whites stick a lot harder to that red than to the black. And there are more rules, for blue blocks, yellow blocks, greens, and purples … rules for different atoms.

Candles are jam-packed with black and white blocks — carbon and hydrogen atoms. And floating in the air are gazillions of red blocks — oxygen atoms. Air is chock-full of oxygen.

(White block) hydrogen atoms stick harder to (red block) oxygen atoms than to (black block) carbon atoms.

Strike a match and light that candle. The energy of the match shakes up the atoms, gives the atoms a chance to follow their “druthers.”

Hydrogen atoms detach from carbon atoms in the candle, and link up to oxygens in the air, which gives the carbon atoms a chance to follow their druthers — carbons, too, prefer to link up with oxygen. Burn a candle and we get carbon bound to two oxygens (carbon dioxide), two hydrogen atoms linked to an oxygen (H2O — water).

At the risk of confusing atoms with people, the atoms are so “comfortable” with this re-arrangement, they give off energy — heat and light.

Burn a candle and we’re doing chemistry. Our bodies do chemistry, too: Biochemistry. And the same rules apply — four white blocks stick to one black, but whites prefer to stick to reds. What makes biochemistry different from ordinary chemistry is, mainly, the size of the sculptures our bodies make with their atoms.

Putting toy building blocks together, we wind up with sculptures some inches, maybe a foot across. Doing ordinary chemistry also results in modest sculptures.

Biochemistry with toy building blocks would result in lots of small sculptures. But — using those little toy building blocks — we’d also get sculptures the size of a car, sculptures the size of a house.

Doing biochemistry with atoms, our bodies make sculptures — molecules — that are humongous, compared to the molecules made with ordinary chemistry. With lots of these special molecules, we put together muscles, eyeballs, brains.

And yet the same old rules apply: Four whites to one black … whites hold tighter to reds.

Attempting to design drugs that could knock down coronavirus, researchers explore ways to trick the virus into building mistakes into their humongous molecules. If a virus were to build its “house” with “doors,” but no “doorknobs,” the bug would be doomed.

Problem is, our own bodies use the very same “doors” and “doorknobs” as the virus. Injecting a patient with defective parts, in hopes of assembling a defective virus, results in a patient with defects, too. Using this strategy, early attempts to design a drug killed off the virus, all right, but it also killed off the lab mice.

There is, though, something about the coronavirus that is different from us. When the virus hijacks our bodies, it commands our cells to make a “machine” — an enzyme — to put new viruses together. And that enzyme/machine is different from any of the enzyme/machines we use to put our bodies together. So the plan now is to inject COVID-19 patients with a defective part for the viral enzyme — a defective part our bodies have no use for.

As drug companies race to invent defective parts to insert into the viral machine, the leader (thanks to university research done years ago) is a molecule called remdesivir (“rem-DEH-sih-veer”). The last three letters — “-vir” — are a tip-off that remdesivir is an anti-VIRal drug.

We’ll no doubt be seeing more drugs ending in “-vir” in the very near future.

looking up

For months, now, planet Venus has been shining bright — brighter and brighter — in the west, every night after sunset. Completely covered in cloud, Venus reflects a lot of sunlight.

As Galileo discovered, centuries ago, Venus imitates the moon: Through a telescope, Venus shows phases. When Venus first appeared in our western sky, last autumn, it was full. Since then, night by night, it’s been getting skinnier. A telescope tonight reveals Venus as a thick crescent.

The full moon is bright. Then, as the moon shrinks — first to a D-shaped quarter-moon, then to an ever-skinnier crescent — the moon sends us less and less light.

For months now, Venus has been growing thinner — from full to quarter to crescent — yet, for all these months, Venus has been growing brighter — the exact opposite sort of behavior we see in the moon. This weekend, and early next week, Venus will reach its absolute brightest.

The trick is that, as the moon orbits the Earth, its distance doesn’t change too much. Two weeks ago, the full moon got about as close as it ever gets, and that “supermoon” was noticeably larger, noticeably brighter than usual … but the extra brightness was nothing like the change we see in Venus … because Venus orbits, not Earth, but the sun.

When Venus was full, last autumn, it was on the far side of the sun from Earth — pretty far away. Since then — even as it’s been shrinking down toward crescent — Venus has been growing closer. And closer means brighter.

Closer = brighter … right up to this weekend. Beginning next week, crescent Venus will grow so skinny, it won’t matter how close the planet gets to us … it’s going to grow dimmer.

So check out Venus, in the west, after sunset … especially next Sunday night, when planet Venus — at its brightest — will share the sky with the crescent moon … the moon within the horns of the Bull.

Al Stahler enjoys sharing science and nature with friends and neighbors on KVMR-FM, and can be reached at stahler@kvmr.org.


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