Why DNA Is So Hard to Visualize

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iStock

Picture a strand of DNA and the image you see will likely be similar to the artist’s rendering above. The iconic twisted ladder, or double-helix structure, was first revealed in a photo captured by Rosalind Franklin in the 1950s, but this popular visualization only tells part of the story of DNA. In the video below, It’s Okay to Be Smart explains a more accurate way to imagine the blueprints of life.

Even with sophisticated lab equipment, DNA isn’t easy to study. That’s because a strand of the stuff is just 2 nanometers wide, which is smaller than a wavelength of light. Researchers can use electron microscopes to observe the genetic material or x-rays like Rosalind Franklin did, but even these tools paint a flawed picture. The best method scientists have come up with to visualize DNA as it exists inside our cells is computer modeling.

By rendering a 3D image of a genome on a computer, we can see that DNA isn’t just a bunch of free-floating squiggles. Most of the time the strands sit tightly wound in a well-organized web inside the nucleus. These balls of genes are efficient, packing 2 meters of DNA into a space just 10 millionths of a meter across. So if you ever see a giant sculpture inspired by an elegant double-helix structure, imagine it folded into a space smaller than a shoe box to get closer to the truth.

[h/t It’s Okay to Be Smart]

Why Is Pee Yellow?

Chloe Effron
Chloe Effron

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Your body is kind of like a house. You bring things into your body by eating, drinking, and breathing. But just like the things we bring home to real houses, we don’t need every part of what we take in. So there are leftovers, or garbage. And if you let garbage sit around in your house or your body for too long, it gets gross and can make you sick. Your body takes out the garbage by peeing and pooping. These two things are part of your body’s excretory system (ECKS-krih-tore-eee SISS-tem), which is just a fancy way of saying “trash removal.” If your body is healthy, when you look in the toilet you should see brown poop and yellow pee.

Clear, light yellow pee is a sign that your excretory system and the rest of your body are working right. If your pee, or urine (YER-inn), is not see-through, that might mean you are sick. Dark yellow urine usually means that you aren’t drinking enough water. On the other hand, really pale or colorless pee can mean you might be drinking too much water! 

Your blood is filtered through two small organs called kidneys (KID-knees). Remember the garbage we talked about earlier? The chemicals called toxins (TOCK-sins) are like garbage in your blood. Your kidneys act like a net, catching the toxins and other leftovers and turning them into pee.

One part of your blood is called hemoglobin (HEE-moh-gloh-bin). This is what makes your blood red. Hemoglobin goes through a lot of changes as it passes through your body. When it reaches your kidneys, it turns yellow thanks to a chemical called urobilin (yer-ah-BY-lin). Urobilin is kind of like food coloring. The more water you add, the lighter it will be. That's why, if you see dark yellow pee in the toilet, it's time to ask your mom or dad for a cup of water. 

To learn more about pee, check out this article from Kids Health. 

Scientists Discover How to Snap Spaghetti Into Two Perfect Pieces

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iStock

Important news for pasta lovers: Researchers at MIT just figured out how to snap a strand of spaghetti into two perfect pieces, according to New Scientist. The days of having to sweep up the tiny fragments that fly in all directions when you break spaghetti into two pot-ready portions are over.

In 2005, researchers in France figured out why spaghetti cracks into bits: The strand flexes in the opposite direction after the initial snap, creating a “snap-back effect” that causes it to break a second time.

Now, after snapping hundreds of spaghetti sticks, MIT mathematicians have the solution. The researchers used a pair of clamps to twist individual strands of spaghetti almost 360 degrees. Next, the two clamps were slowly brought together to bend the stick, resulting in a perfect fracture. This worked for two kinds of spaghetti with different thicknesses—Barilla No. 5 and Barilla No. 7, to be precise.

The process was recorded using a high-speed camera (which can be viewed on MIT's website). While reviewing the footage, researchers realized that adding a twist is key because it prevents the spaghetti stick from forcefully flexing backwards. Their findings were published in the Proceedings of the National Academy of Sciences.

Even without equipment, you can can try this at home. It might take a bit of practice, though, so have a couple of boxes handy. Ronald Heisser, a former MIT student who is now a graduate student at Cornell University, came up with the technique for how to manually snap spaghetti in two.

“I would start with my hands opposite each other—one hand upside down and the other right side up—and then make both of them right side up while twisting the spaghetti so you can work your arm strength into it,” Heisser tells Mental Floss.

“You know you're twisting it right when you feel it really trying to untwist itself. Then, you can carefully bring the ends together, trying not to change the twist at all.”

He noted that your hands should also be dry, because oiliness can make the strand slip in your fingers.

However, it's unlikely that anyone has the patience to sit there and snap one strand of spaghetti at a time. So does this trick work for a whole handful of pasta? Dr. Jörn Dunkel, who led the study, says it’s difficult to predict how a handful of spaghetti would fracture, but he believes this technique would reduce the number of pieces you end up with.

“When many spaghetti [strands] become bunched together, they can transfer energy between them, which can change their bending and fracture behavior significantly,” Dr. Dunkel tells Mental Floss. “Very roughly, as a rule of thumb, one would expect that splitting the energy between bending and twisting should always help to reduce the fragment number compared to pure bending.”

Of course, if you want to cook the true Italian way, you’ll leave your spaghetti unsnapped and intact. (Longer pasta is said to wrap around your fork better, making it easier to eat.)

But if you want to try this bend-and-snap technique for yourself, the purists would probably give you a pass.

[h/t New Scientist]

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