What are we made of?

This is a very interesting question that most people couldn't answer. As a chemist, I am absolutely fascinated by the complexity of what goes into making our bodies.

Essentially, the human body is composed of water, protein, connective tissue, fats and bones as well as carbohydrates, and DNA. Most of these contain carbon, oxygen, hydrogen, nitrogen, calcium and phosphorus. There are tiny amounts of sulfur, sodium, potassium, chlorine, and magnesium as well as tiny amounts of other elements. Obviously, the main element in our body, other than the hydrogen and oxygen in water, is carbon, hence the reason that we're considered a carbon-based life form. Most of the mass of our body is composed of Oxygen, Carbon and Hydrogen, in that order.

Remember that the human body is composed of individual cells in the tens of trillions, and they comprise some basic tissue types, including muscle, fat, bone, nerves, hormones, blood, and lymph.

Okay, now that we've seen the big picture, we have to get down into the micro world to really understand how we're constructed. All human cells have DNA (contained in chromosomes) in the cell nucleus, and DNA has the blueprint for every thing that goes into constructing us. You could think of DNA as a parts manual, a list of the things that go into a complicated machine, which is our body.

There are 22 different human chromosomes, plus two sex chromosomes for a total of 20 thousand to 25 thousand genes, over 3 billion base pairs and over 2.5 billion sequenced base pairs. Each cell in our body has these and a copy, making it a total of 46 chromosomes. That's a lot!

DNA has the code for the construction of proteins. Proteins are essentially the materials that make up our tissues or the molecules that can be converted into what's needed. Upon cursory observation proteins don't seem all that complicated. A protein is essentially a polypeptide, a chain of various amino acids connected together by means of the peptide bond, which is carbon (double bonded to an oxygen as in C=O) linked to nitrogen that has hydrogen attached as in N-H. The chemical bond in peptides is accomplished by removing an O-H from the acid group of an amino acid and the H from the amino group of another amino acid. The result is that a water molecule is released and a peptide bond created. An enzyme catalyzes this chemical bonding as in the case of most biochemical reaction in our bodies.

The chemical structure of a peptide (a short chained protein) depends upon the sequence of amino acids in its chain. There are 20 different amino acids that can be used to make a protein. All amino acids have the amino group (NH2 - two hydrogen connected to a nitrogen) and the carboxylic acid group (C=O with a OH) linked by a carbon that has a hydrogen atom attached. Each amino acid has a specific group attached to the common carbon atom. I won't go into the structure of all of them except to say that some have aromatic groups and other heterocyclic structures. In other words, they're not simple.

DNA, when split into RNA, is capable of constructing proteins. This is known as biosynthesis, or more specifically, translation, and it does this by creating messenger RNA strands that contain the proper arrangement of base units on the RNA that are needed to create a specific protein. The amino acids are attached to special t (transfer) RNA molecules by means of an enzyme. These transfer molecules act like workers to make it easier for the messenger RNA to do its job. Basically, the t RNA molecules with their attached amino acids line up on the messenger RNA strand and when it's ready, the bonds between the amino acids are linked by means of an enzyme and the protein is released. This is a simple explanation of a much more complicated process.

This is how the tissues of our body are constructed. It's chemistry at its finest complexity. However, proteins are not so simple as one might think. They are complicated 3D structures that are twisted and coiled into specific arrangements that resemble those coiled up ribbons you see at a kid's birthday party. In the case of proteins, they're mixed together to make a ball that resembles a clump of coiled ribbons. It's amazing that chemists have devised ways to see these structures in three dimensions. They use X-ray crystallography to do this, but it's very complicated.

What's really fascinating about the human body is that everyone's body is created from two cells, a sperm cell and an egg cell. These two cells are microscopic, yet they end up creating all of the complex tissues and components of our bodies. The chromosomes from the mother and those from the father are split to create a unique individual. Wow!

I wrote this to convey how complicated our bodies are and the exquisite manner in which it was constructed from DNA. If anything could reflect the brilliance of a creator this amazing biochemical process certainly does. I believe that it proves that we are the ultimate example of God's creation.

Thanks for reading.