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!
