Hey, chemistry nerds!
Do you have any special plans for this Sunday?
Because it’s Mole Day!
Mole Day is celebrated on October 23rd, starting at 6:02 AM.
It’s a play on Avogadro’s number, which is 6.022 times 10 to the 23rd power.
That’s a very big number,
and it’s used to describe huge amounts of very small things
like atoms or molecules.
Each atom has a unique atomic weight.
And if you have that number of grams of an atom, then you have a mole of them!
This is really useful in chemistry,
because two moles of any two compounds will have the same number of molecules.
That way, you can talk about how many moles of stuff you have,
which is usually a much easier amount to wrap your head around,
and plan out balanced chemical reactions.
But you might be wondering – how did Avogadro come up with such a number?
It’s simple, actually.
He didn’t.
The Italian scientist Amedeo Avogadro
actually described what we now call Avogadro’s Law in the early 1800s.
Avogadro proposed that two gases of equal volume
at the same temperature and pressure contain the same number of molecules.
But he didn’t have a way to count them, and prove his hypothesis.
That came around a hundred years later,
long after Avogadro had gone to that great Bunsen burner in the sky.
The key piece in the puzzle was when the physicist Robert Millikan
discovered the charge of an electron.
See, scientists knew the charge of one mole of electrons already,
which is equal to a constant called one Faraday.
And the charge of one mole of electrons divided by the charge of one electron
gives you the number of particles in a mole: 6.022 times 10 to the 23rd.
But it was another scientist, Jean Baptiste Perrin,
who first called the constant Avogadro’s number in his honor.
Estimates of the number have improved over time,
because with better technologies comes more accuracy.
But the mole has been on high school chemistry tests for a long time.
So if you want to pay tribute to Avogadro this Mole Day,
maybe tell some chemistry jokes, or make some liquid nitrogen ice cream,
or get yourself some avocados and make guacamole.
In other biochemistry news, researchers may have reached
a new milestone in producing a drug that treats malaria.
And taking the medicine might be as simple as eating your vegetables.
We all know that malaria is a huge problem, infecting millions of people every year.
So researchers are doing everything they can think of to stop this parasite
from spreading, and to cure anyone with the disease.
One of the most effective treatments today is a drug called artemisinin,
which quickly binds to important proteins in the parasite, and kills it.
The discoverer of this compound, Chinese scientist Youyou Tu,
netted a half share of the Nobel prize in medicine in 2015
that’s how important it is in the fight against malaria.
But there’s one major problem:
only small amounts of the compound occur naturally
in the sweet wormwood plant, which is hard to grow in the first place.
That makes the drug really expensive,
and many of the people who need it the most don’t have that kind of cash.
Now, this week in a study in the journal Molecular Plant,
Indian and American researchers have made the drug much easier to get,
by genetically engineering tobacco plants to make artemisinin.
Tobacco might seem like a weird choice, but it’s a common model organism
for plant researchers because it’s easy to grow and genetically alter.
Plus, the chemistry of artemisinin is finicky,
so only plant cells are really good at making it.
That rules out other methods that we use to synthesize drugs,
like growing them in genetically-modified yeast or bacteria.
To be clear, these aren’t the first scientists to try
and make artemisinin in different plants.
But their tobacco plants grew much more of the drug than previous studies.
Even better, they found that that the drug works when it’s left inside plant cells.
They fed some crushed leaves from the engineered tobacco plants to mice,
and those mice had fewer malaria parasites swimming around in their blood.
That means there’s no need to spend time and energy
purifying the drug from the tobacco.
Plus, the drug actually seems to perform better
encapsulated in plant cells than as a pure compound.
The researchers think that the plant cells act as protection
from the mouse’s digestive system,
which gives the drug extra time to enter the bloodstream and do its job,
instead of getting digested.
Now, you might be thinking, “Okay, but it probably isn’t great
to start feeding sick people a bunch of tobacco leaves.”
It seems like trading one serious health risk for another.
And that’s why the researchers are trying to duplicate this feat
in more traditionally edible plants, like lettuce.
Imagine that – someday, we could have an artemisinin-filled salad that cures malaria.
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