You might already know that proteins are a fundamental part of your diet, but proteins
aren’t just nutrients you need for building muscles and running around.
Proteins are much more interesting than that, however before explaining what proteins really
are, and what they're made of, we need to talk briefly about one of my current favorite
topics: molecular representation.
You see, a protein is a molecule, which might not be evident to most people because molecules
are usually represented like this or this.
It turns out, however, that this diagram, aptly named a ""ribbon diagram"", is just
one of the many ways to represent proteins.
And look, initially, I wasn’t super happy with all of the freaking ways to represent
the same exact thing, but when you consider that humans consistently use several representations
for the same concept, and that proteins are so small they’re literally invisible (or
at least challenge what “visible” is), then you start to understand the need for
different models.
Each model captures only some of the features of the molecule, but in the end they’re
all simplifications.
In a ribbon diagram, you don’t see the individual atoms or the surface of the protein, however
you can see how a protein is a single chain that folds into a specific structure.
The path of the chain is where the backbone of the protein is located.
Side chains are attached to the backbone, but they aren’t displayed in the ribbon
diagram because that would obscure the structure.
If you took the backbone, unfolded it and labeled the different atoms in it, you’d
quickly identify a repeating pattern; that’s because the chain is actually a sequence of
special molecules called amino acids, all of which share a common set of atoms that
make up the backbone.
There are 20 different amino acids, each with a side chain that has a different shape and
different properties.
Thousands of amino acids can combine to form a single chain, which depending on its length
and the order in which the amino acids are clicked together, can fold into different
and unique structures.
This folding happens because in the molecular world, everything is constantly jiggling,
which exposes different amino acids on the chain to each other, allowing them to interact
by attraction and repulsion, just like magnets.
These interactions can make the chain fold into rigid helical shapes, or smooth, flat
sheets, which can interact with each other too, resulting in a stable configuration:
what we know as a protein.
And the different properties of the amino acids, and the incredible diversity of protein
structures are what make it possible for proteins to play central roles in almost every biological
process: some proteins can attach to other proteins to build precise infrastructure;
others will identify and neutralize invading pathogens; others will function like molecular
factories and transform raw materials into finished products; and there are even proteins
that can harvest energy from sunlight, which are the ones plants use during photosynthesis;
because yes, plants are full of proteins too!
In fact, every cell in every living organism is full of proteins, and when an organism
eats another, the proteins in the unlucky one will be split back into amino acids, which
will then be recycled to create all sorts of new proteins for the lucky organism, including
special proteins that will allow muscles to contract and organisms to move toward their
next protein-rich meal.
And, of course, protein-rich meals are critical for people too!
That’s why, with the help of Tab for a Cause, we’re supporting Action Against Hunger,
a nonprofit organization that’s been treating undernutrition in children and their families
in 45 countries for 40 years.
Right now, Tab for a Cause will donate $1 to Action Against Hunger for every MinuteEarth
viewer who downloads their browser extension at tabforacause.org/MinuteEarth2.
That’s in addition to the money raised for Action Against Hunger and other great charities
every time you open a tab when you have the Tab for a Cause extension.
Thanks, Tab for a Cause!