Hey it's professor Dave, let's learn about pharmaceuticals.
We all get sick from time
to time. Whether it's just a cold, or
something more serious, and there's great
controversy amongst the public about how
to treat disease.
Some argue that conventional medicine is
best suited to address the health needs
of the human body, while others are
skeptical, avoiding the entire system in
favor of some kind of alternative. But
before anyone discredits Western
medicine, they must understand that all
disease has a molecular basis. Whether
the cause is bacterial infection, a
genetic mutation, or anything else, any
proposed treatment that does not address
this fundamental cause for the disease
is very unlikely to have any merit. So
let's examine a few types of diseases
and the methods that science has come up
with to combat them, which we can refer
to as drugs. One category of disease is
genetic disorder.
These can be hereditary, passed down from
parent to offspring or they can be the
result of a mutation sustained during a
person's lifetime.
These will always involve some change to
DNA that affects the product of gene
expression, resulting in a protein with
behavior that deviates from what is
normal. If we need to shut down a
particular biochemical process that has
gone awry, one solution that we have
stumbled upon in science is the concept
of an inhibitor. We know that there are
enzymes and receptors that mediate so
much of what goes on in the cell, and
sometimes we may need to silence one of
these. An inhibitor is a molecule that
will fit into the active site of, say, an
enzyme, and bind either reversibly
through electrostatic interactions or
more permanently through covalent bonds,
such that the normal substrate is unable
to enter. This kind of inhibition, called
competitive inhibition, prevents the
substrate from coordinating and
therefore also prevents the enzyme from
performing its function. There is also
noncompetitive inhibition, where a
compound binds to the enzyme in some
other location and causes a
conformational change that decreases the
active site's affinity for the substrate.
This also disrupts enzymatic function.
Many poisons work this way, and are
dangerous because of the important
cellular processes they inhibit. But when
an irregular cellular process is doing
harm to the organism, an inhibitor can
stop this activity. Inhibitors are
therefore a huge part of the
pharmaceutical industry. We have to
recognize that if a disease such as some
form of cancer is the direct result of a
genetic mutation and results in either
a misbehaving or non-functional
protein, then that is the fundamental
cause of the disease. Any potential
solution or cure must specifically
address that cause, by somehow
inhibiting the expression of that gene,
inhibiting the resulting protein, or some
other similar biochemical strategy.
When the cause is this specific, there is
nothing about diet or exercise that can
have any impact whatsoever, since your
general health, as important as it is,
is not linked to the highly specific origin
of such a disease. That's why skepticism
towards the pharmaceutical industry,
which can certainly be legitimate from a
social or economic standpoint, if
misplaced onto the science itself, can
have disastrous consequences on the
health of an individual or an entire
population. Another application for
inhibitors can be found in the domain of
mental health. We learned about
neurotransmitters, and it is the case
that molecules like serotonin, dopamine,
and norepinephrine will dictate your
mood by transmitting signals through the
synaptic cleft. If these
neurotransmitters exist in insufficient
concentrations, it can lead to depression.
One solution to this problem is to use a
reuptake inhibitor. This is a molecule
that blocks the receptors that reabsorb
some of the neurotransmitter molecules
which results in a greater
concentration of neurotransmitters in the
synaptic space, and therefore more
effective transmission. Once again, the
fundamental cause of the problem is that
not enough of a particular molecule is
being transmitted, so a drug that
addresses that problem by increasing the
transmission of that molecule one way or
another is going to be best suited for
solving that issue. In this way, those who
criticize antidepressants as being
merely a chemical solution to a deeper
problem are not fully aware of the
specific chemical nature of the problem
in the first place.
This does not mean psychotropic drugs
are the solution for every mental health
issue, but they can be very successful
for certain people. Some diseases are the
result of some kind of deficiency in an
essential vitamin or mineral.
Take vitamin C, for example. As we now
understand, this molecule, also called
L-ascorbic acid, acts as a coenzyme in
certain enzymatic pathways, such as
collagen synthesis. Collagen, a structural
protein present in connective tissue, is
the most abundant protein in the human
body, and vitamin C is needed to activate
the enzyme that performs one of the
steps in synthesizing collagen. If we do
not consume enough vitamin C, collagen
synthesis is impaired and we get scurvy,
like a pirate on the high seas.
The reason this would happen is that
vitamin C is predominantly found in
fruits and vegetables, and these tend to
spoil during a long journey. A vitamin is
therefore just a molecule that we need
to ingest for proper cellular function
because we can no longer synthesize it
ourselves, as the ability was lost
somewhere over the course of biological
evolution. But plants still make all
these nutrients, so as long as we eat the
plants we will be just fine.
The amazing feat of modern chemistry is
to recognize the link between a disease
like scurvy and a molecule like ascorbic
acid, and furthermore to know the
structure of this molecule such that we
can build it ourselves, and
offer it in the form of supplements to
those who do not have access to the
whole foods that contain them.
Contrary to popular belief, there can be
absolutely no difference between a
molecule of ascorbic acid found in a
fruit and one made in a lab, because they
are identical arrangements of precisely
the same atoms. It is the shape of a
molecule that causes its bioactivity, not
its source. Another category of disease
is the pathogenic. A pathogen is any
microorganisms that can cause disease
like bacteria or viruses. Most bacteria
are harmless or even beneficial to the
human body, but there are some that cause
infectious diseases, like tuberculosis or pneumonia.
It was not that long ago that we were
completely unaware that these organisms
even existed. But once we realized that
they were responsible for certain
diseases, our studies of these organisms
led to the invention of antibiotics,
which can kill certain bacteria. Many of
these operate on the basis of a
difference between bacterial cell
structure and human cell structure.
Bacterial cells possess a cell wall made
of a substance called peptidoglycan,
which human cells do not possess. The
first antibiotic ever discovered,
penicillin, inhibits a bacterial enzyme
that is used to regenerate the cell wall.
So in the presence of the drug the cell
wall of bacterial cells will rupture,
spilling their contents and thus killing
the bacteria. Antibiotics like penicillin
and others that followed have almost
single-handedly doubled the human
lifespan. Viruses, however, have different
structures and mechanisms of survival
from bacterial cells, as viruses are not
cells at all, they are much tinier and
operate by inserting their genetic
material into a host cell, hijacking the
cellular machinery, and forcing it to
generate more viruses, while typically
destroying the cell in the process. Thus,
antibiotics do not work on viruses.
Instead, vaccines have proven effective
in training the human body to prepare
a response to certain types of viruses
by introducing a piece of the virus so
that the immune system can recognize and
remember it for optimal future response.
This is how we have largely eradicated
many diseases like smallpox, polio, and measles.
However, again, skepticism of vaccination
threatens to facilitate the return of
some of these diseases. For other viruses
a more complex approach is required, but
any legitimate antiviral drug will
disarm some biochemical process that the
virus relies on. For example, in order to
invade a host cell, receptors on the
virus must recognize certain receptors
on the cell. If inhibitors are introduced
that block either of these receptors, the
virus will not be able to enter and
reproduce. Other drugs can inhibit the
transcription of viral DNA once it is
inside the cell. And ribozymes are
specially designed enzymes that can
target viral DNA and chop it up so it
can't be transcribed. Whatever the case
may be, any legitimate treatment must be
preceded by a sophisticated knowledge of
the biochemistry involved.
By contrast, some diseases are strictly
physiological, like many forms of
cardiovascular disease. These involve the
heart or blood vessels and can occur
because of poor diet, lack of exercise, or
other lifestyle factors. These are the
ones in which a holistic approach to
general health can be effective in
preventing, but there are also
medications that offer some assistance.
All of these systems will be covered in
greater detail in the upcoming biology series.
So we must understand that in
order to treat a disease, it is
imperative that we understand how it
operates on the cellular and molecular
level, and then come up with a strategy
that addresses some detail on one of
these levels. That is the approach of
pharmaceutical drugs, which are specially
designed molecules that can inhibit
specific biochemical processes.
This allows us to eliminate pathogens,
silence mutant enzymes, and more. If by
blind chance an
ancient tradition has discovered a food
or plant that has legitimate medicinal
properties, which is certainly possible
since humans have been curious and bold
enough to try things far before we
understood chemistry, that substance has
those medicinal properties because it
contains an active ingredient, some
molecule inside it that performs a
biochemical function similar to the
strategies we have discussed, not because
the plant as a whole is sacred or magic.
Everything in your body is made of
molecules, and every biological process
involves the interaction of those
molecules. Unfortunately, most people do
not have a background in chemistry and
biochemistry
so when trying to make assessments about
health and medical treatment they must
simply go by what they have heard. But
there is a lot of misinformation out
there, whether it is genuine
misunderstanding or deliberate
manipulation for financial gain. A
vilification of Western medicine is a
popular meme that leads people away from
legitimate medical treatment, as they
instead opt for alternative medicines
with no real impact other than a placebo
effect, which can be enough to cure your
headache, but will never cure your cancer.
Luckily, as you continue to build your
understanding of science, you won't be so
easily manipulated.
Thanks for watching, guys. Subscribe to my channel for more tutorials, and as always, feel free to email me:
