What are CHNOPS? These Chemical Elements = 98% of Life | Biology | Biochemistry


CHNOPS are the most common elements in living
organisms. Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus,
and Sulfur. These elements make up 98% of living matter
on Earth. Why should you study CHNOPS? If you understand the chemical behavior of
these 6 elements, you’ll understand almost all of biochemical reactions. CHNOPS make up 99.7% of bacteria. And they make up 97.9% of humans. It takes just 4 elements: Oxygen, Carbon,
Hydrogen, and Nitrogen – to make up 96.2% of humans. Let’s start with CARBON. Carbon is about 18% of humans, by mass. We say Earth has carbon-based life forms. Why do we say that? Because of the carbon backbone. Carbon makes up the skeleton of most biological
molecules, including Proteins, carbohydrates, lipids, and nucleic
acids. Carbon has 4 valence electrons – this lets
it make a variety of bonds. 4 single bonds, 2 double bonds, a single bond
and a triple bond… So, as a result, you can make lots of different
stable structures. Imagine we were talking about legos, or tinker
toys. If you can join together a piece in 4 different
ways, you could make a lot more structures than something with only one connection or
two connections. Silicon has similar chemical behavior. It also has 4 valence electrons. So maybe….we might find a planet one day
that had a slightly different start in life, and wound up with silicon-based life forms. Now, HYDROGEN. Hydrogen makes up about 10% of humans. We find Hydrogen in water, H2O, so it’s
not surprising it makes up so much of living matter. We are about 60% water. Some organisms are as much as 90% water. We’ll address this idea – how vital water
is to life – in another video. Hydrogen is especially active in its ionic
form, H+. Acids increase H+ concentration, while Bases decrease
H+ concentration. So Hydrogen plays an important part in acid-base
behavior, which is involved in a lot of biochemical reactions. NITROGEN. This is an essential component of DNA – think
of those nitrogenous bases that make up the rungs of the DNA ladder. Also be on the lookout for nitrogen in amine
groups, like on the ends of amino acids. These amine groups confer basic (as opposed
to acidic) behavior. Nitrogen makes up about 3% of humans. Nitrogen is also especially abundant in the
air that we breathe (about 78%). OXYGEN. Oxygen is also found in water, H2O, so you’d
expect a lot of oxygen in living matter. Oxygen makes up about 65% by mass of the human
body. We also breathe oxygen, O2. In chemistry, Oxygen is important in oxidizing
reactions. It’s going to grab electrons and become
negatively charged. Some people think antioxidants are important
to slow down our internal oxidizing, or rusting, if you will. PHOSPHORUS is found in the backbone of DNA. Remember the backbone goes “sugar-phosphate-sugar-phosphate.” We also find those phosphate groups in ATP,
which is the key form of energy currency in biochemical reactions. Phosphorylation and dephosporylation events
are really important in biochemistry. This is often used as a signal or as a trigger
for conformation changes in biological molecules. We also find phosphates in phospholipids,
which are an important component of cell membranes. Phosphorus makes up about 1% of humans. And finally, SULFUR. Sulfur is found in two amino acids – cysteine
and methionine. You’ll learn that amino acids string together
to form proteins, and these are 2 of the 20 amino acids. The sulfurs from these amino acids tend to
bind together, forming disulfide bridges. This is part of what holds a folded protein
together in its final 3D shape. A few organisms use selenium instead of sulfur. But for most organisms, it’s a fundamental
part of what makes us. 0.25% of humans are sulfur. Another significant element for humans is
CALCIUM. Calcium makes up 1.5% of the human body – almost
all of it found in mineral compounds in bones and teeth. But its chemical behavior as an ion is where
we see its most dramatic functions, acting – for instance, in neuron signalling and muscle
contraction. All the elements used in very small amounts
are called TRACE ELEMENTS. These include:
Iron – we need that for hemoglobin Sodium and potassium, important as electrolytes,
used in signalling/ neuron function. Iodine, needed for your thyroid hormones. I think the details of all the trace elements
probably belong in their own video. Next we’ll look at how these elements interact
with each other, forming bonds and making the great variety of biological molecules. Here’s a challenge for you – name a biological
molecule that contains only the elements in CHNOPS. For example, any given sugar is made up of
Carbon, Hydrogen, and Oxygen. Like glucose: C6H12O6. Your job is to find another molecule containing
only CHNOPS or a subset of those elements, and write it in the comments. If you have something else you’d like to
talk about, write it in the comments as well. Keep it clean, and let’s focus on the science. If you found this video helpful, please give
it a like and share it with your friends. Post it on Reddit. Twitter it. That’s how we grow as a channel. You can get even more friendly with Socratica
by joining our Patreon Team. Patreon lets you support your favourite creators
for as little as $1 a month. It’s a huge help for us to make more videos,
and it lets us really know you’re with us. Thank you.