As science fans, you probably heard that this year’s Nobel Prizes were announced last
week!
And if you’re a regular SciShow Space viewer, then you’re probably familiar with the research
on gravitational waves that won the physics prize.
But the work being honored in the fields of physiology and chemistry deserve some love
too, so let’s dive right in.
The Nobel prize in physiology or medicine went to Jeffrey Hall, Michael Rosbach, and
Michael W. Young for their work on biological clocks.
Many living things, including humans, have internal clocks that help them stay synced
with the rotation of the Earth.
You can see this in flowers that open and close at specific times of the day, or animals
that become more active at sunrise and sunset.
All sorts of human bodily functions, from your metabolism to your hormones, fluctuate
over the course of a day according to this internal timer.
And for a long time, no one was exactly sure how it all worked.
In the 1980s and 1990s, though, these scientists isolated a series of genes in fruit flies
that started to clear things up.
Previous work had identified a gene named 'period' in fruit flies that seemed to throw
their daily behavioral cycles out of whack when it was mutated.
And Hall, Rosbach, and Young managed to isolate and figure out the DNA sequence of this gene.
The gene encodes a protein, called PER.
And Hall and Rosbach found that PER builds up in every single cell at night and then
gets broken down during the day.
Later, they discovered a couple more fruit fly genes that help regulate this daily PER
cycle.
Young found a gene named 'timeless' that produces a protein that binds with PER and lets it
enter the cell nucleus, where all the DNA is stored.
Here, the two proteins can interact with the period gene, stopping it from producing more
PER.
Scientists call this a negative feedback loop, where the output of a process causes the process
itself to slow down.
Young also found a third gene, called doubletime, that encodes a protein that slows down the
buildup of PER.
By controlling the switch between PER production and breakdown, 'doubletime' allows the timing
of the feedback loop to adjust to the planet’s 24 hour cycle.
These clock proteins tell all sorts of other genes in cells to dial their activity up and
down, which in turn affects what different organs are doing in something’s whole body.
Now, the research to identify these genes may have been done in fruit flies, but the
same process is at work with slightly different molecules in most organisms -- including humans.
These discoveries have helped spur a whole new field of research of circadian biology,
which influences our health and wellness in ways we’re only starting to understand.
In chemistry, meanwhile, the Nobel Committee awarded this year’s prize to Jacques Dubochet,
Joachim Frank, and Richard Henderson.
Over the 1970s, 80s, and 90s, they developed a technology that let scientists freeze organic
molecules and examine them up close, called cryo-electron microscopy.
And this technique has helped us reveal how some of the smallest processes of life work.
Electron microscopes can theoretically be used to image tiny things that light microscopes
can’t, like cell structures or proteins.
But, in the 1930s, they only used to be good for looking at things like the structures
of crystals or dead cells.
There are a couple different types of electron microscopy, but they both rely on a powerful
beam of electrons shooting at or through a sample to make an image.
That beam can destroy organic material, so you couldn’t really look at whole proteins
or viruses, for instance.
These microscopes also need to be in a vacuum to work, because the electron beam can run
into gas molecules floating around.
But in vacuums, any liquid water around biological molecules has room to escape and become water
vapor, which makes cells break down.
These three researchers have made it possible to use this powerful technology to study the
molecular machinery of life.
First, Henderson figured out how to use a weaker electron beam that wouldn’t destroy
a cell sample, although the images had a lower resolution.
Not only that, but he realized he could coat a protein sample he was studying in a glucose
solution, which protected it enough to keep it from drying out in a vacuum.
Even though this technique made fuzzy images, Frank developed a way to combine multiple
fuzzy 2D images taken from different angles to produce a sharp 3D model.
Frank’s other contributions came in refining the computer programs used to process microscopy
images.
The final breakthrough came when Dubochet found a way to freeze different kinds of samples
in water to fully protect them from the vacuum’s dehydrating effects.
Chunky ice crystals don’t work because they mess with the microscope’s electron beam…
but the ice you throw in your lemonade isn’t the only form of frozen water.
Using liquid nitrogen at around negative 196 degrees Celsius to cool ethane, Dubochet was
able to plunge water molecules inside and freeze it so rapidly that it formed a smooth
glass-like solid called vitrified water.
This form of water lets electrons pass through as easily as liquid water, but it keeps cells
frozen in time and intact, even in a vacuum.
Today, these techniques let scientists map receptors in cell membranes that sense temperature,
identify proteins that let bacteria resist antibiotics, and peek at the structure of
viruses to look for new ways to target them with drugs.
Among /many/ other applications.
So congrats to all of this year’s Nobel honorees from all of us at SciShow -- your
work helps introduce all of us to the wonders of the universe, massive and microscopic.
And thanks to all of you for watching this episode of SciShow!
If you haven’t seen our videos on gravitational waves, you can check them out on SciShow Space.
And if you just want more of all kinds of science, we’re at youtube.com/scishow.