The cell - a miracle of cooperation

In one corn plant there about a billion of cells. They are the building blocks of all the structures of the plant. Textbooks commonly give the impression that science knows most of what is worth knowing about them. No doubt a lot is known. But what textbooks commonly don't tell is that this knowledge is very fragmented and incomplete, especially when it comes to the "heart of the matter", the DNA, the molecule carrying the blueprint of life in a sequential code. I wrote this to give you an idea how the cell works and how incomplete the knowledge is.

According to molecular biology, DNA controls what happens in the cell by regulating the manufacture of proteins. This manufacture occurs by linking amino-acids, (small molecules) into long chains. It is DNA that decides the amino-acid sequence. The piece of DNA deciding the sequence of a whole protein is called a "gene". The amino-acid chains, the proteins, are multipotent molecules that can perform many different functions. They are the very key molecules of life.

The proteins

The properties of a protein are decided by its form. The form of a protein is decided by its amino acid sequence. There are twenty different amino acids. They have different chemical and electrical properties. These give rise to forces that will make the amino acid attract or repel each other in different directions and with different stregth. When amino acids are linked in a chain, the chain will fold in accord with these attracting and repelling forces. This folding pattern will mold the protein into a globular, oblong, spiraling or almost any other form. There may be folds with such electrical properties that a specific molecule, for example a mineral is attracted into it. This will give the combined molecule+mineral complex very special new properties. Othe folding patterns make proteins combine with other molelules that contribute to the diversity of properties. So the possibilities to create molecules with very diverse properties just from various folding patterns are practically innumerable.

Let us now learn more concretely what proteins may come out of the various folding patterns:

The structural proteins are the basic building material of all the many structures constituting our body. Proteins may have the form of long spiraling fibers like in hairs, connective tissue or muscles. They form the semipermeable cell wall and the wall of the different vesicular or tubular structures in the cell. In some cases some mineral is accumulated in the cell, like in bone, or large amounts of fat or other substances are deposited in the cell. But these processes are all regulated by the proteins and it is the proteins that lay out the matrix and constitute the forming material of these structures.

The enzyme proteins is the other major category. They work as promoters of biochemical reactions. By making chemicals combine that would not otherwise do so, they provide an elegant and powerful key to the regulation of chemical processes n the cell. Their presence will increase the rate of such reactions enormously. And their absence will reduce them to a low or zero level. This is why DNA can govern the chemical activities in the cell by controlling the amount of different enzymes produced by the ribosomes.

In addition, there are many proteins with special functions. Among the most important are the DNA-regulator proteins, the potent hormones, the antibodies of the immune system, and the peptide neurotransmitters of the nervous system.

The regulator proteins are an important part of the system that controls the activity of the DNA. They decide if a certain part of DNA shall be active or not.

The hormones stimulate the activity of DNA, often only in certain categories of target cells, like the sexual organs in the case of sex hormones.

The antibodies identify foreign substances and hook onto them, guiding the cells of the immune system to destroy the intruder.

The peptide neurotransmitters were first believed to act only in the brain by stimulating different activities. Now it has been found that many cells in the body including the immune system can be stimulated by these, that represent a global signal system of the body.

This brief description is by no means exhaustive. It just gives some idea of the enormous diversity of proteins.

So the DNA can, just by commanding the making of different amino-acid sequences, create an enormous diversity of structures and regulatory molecules. This is why a single embryonic cell, born at conception, can differentiate into all the different structures of the body. So all the cells in the body have identical sets of chromosomes. But because different parts of their chromosomes are active, producing different proteins, the cells will have very different appearance and function.

Cellular function

When we see a picture of a cell, we loose an important dimension - the intense and dynamic flow of materials that constantly goes on throughout the lifetime of the cell. Thousands of different chemical reactions occur every moment.

As explained above, the protein synthesis is a means for regulating all the innumerable biochemical reactions inside the cell through enzymes and regulator proteins. It is also a means for communication with other cells by means of peptide signal molecules. It provides building materials for the cell. It provides also substances that can be excreted to influence other parts of the body like hormones.

Synthesis of all other substances like nucleic acids, amino acids, carbohydrates and fats all occur in different specialized parts of the cell through the action of different enzymes, as always under the control of DNA.

Extraction of energy from fats, sugars and amino-acids occurs in the powerhouses of the cell, the mitochondria. They are considered to be relicts of bacteria that invaded the cells billions of years ago and established a symbiotic cooperation with the cells. Therefore the mitochondria have an own DNA different from the DNA in the cell nucleus.

This is just a very brief and incomplete description to convey some idea of the rich variety and complexity of the multitude of events that occur every moment in the cell.

All these very different activities must be very closely monitored and coordinated, otherwise chaos would appear in the hectic and very multifaceted cellular processes. This requires an incredibly complex, precise timing and tight regulation by the DNA of the cell. The knowledge about this regulatory system is yet very incomplete. This was recently put quite drastically by a world leading expert on how genes function, Dr. Craig Venter who has spent many years to map all the genes of the human body attempting to understand how they work. He said ""We know far less than one per cent of what will be known about biology, human physiology, and medicine. - My view of biology is 'We dont know shit.' " (Source: "The Genome Warrior", The New Yorker Magazine, June 12, 2000.)

Only a fraction of DNA is known

The genes, the protein coding stretches of DNA, constitute only a few percent of the DNA. The rest has been called "Junk DNA" by molecular biologists, since they were unable to attribute any function to this DNA. However, a decade ago some scientists found that this "Junk" was arranged in an orderly manner, with a structure indicating som kind of language. Research has since indicated that this DNA may have important functions, but very little is yet known about it and its language code is unknown (for more, see "Junk DNA").

Microtubles - another regulatory system?

A recent idea is that the tubular scaffolding that radiates from cell nucleus in all directions, the microtubules, might have a regulatory function, perhaps mediated through laser-like light impulses generated within the tubules. This is a speculation today, supported only by indirect evidence, but it is seriously considered as a possibility by some scientists. This I want to mention just to indicate that there might be additional important but yet very incompletely known or unknown aspects of the regulation of cellular functioning.

The outdated physics of Molecular biology

Molecular biology treats the molecules of life like micro-objects. However some leading physicists have pointed out that there is a deeper dimension of life that has been addressed very little by biological sciences. It is the quantum mechanical field aspect.

In studying nature, biological science generally applies the "classical mechanical" aspect of physics. This stems from classical physics, that was created by Isaac Newton 300 years ago. In Newton's classical mechanics, matter was believed to be made of solid particles. This view was very successful in describing the gross behavior of physical systems. But in the end of the last century it was found to to be seriously inadequate for describing the behavior of the finest constituents of matter. This insight lead to the emergence of quantum physics that appeared in the beginning of this century. According to quantum physics, there is actually no solid matter at all. Matter is actually a field phenomenon (QM calls it "matter fields").

This is may seem unfamiliar and abstract to many. So let me explain with an analogy: Magnets have two poles, called North and South. When you take two strong magnets and try to bring the North poles together, you will find it impossible, because their fields repel each with increasing strength the closer they are. If you were blindfolded and did not know that you held a magnet in your hand, you would get the feeling that you brought the magnet into a solid elastic object with a hard core. Similarly matter actually is nothing but fields attracting and repelling each other.

In some conditions these fields act in a concentrated way behaving like particles and in other situations they behave like waves. This is called the wave-particle duality. Classical physics deals only with aggregates of particles as if they were solid objects. In most cases this is a good approximation of reality, as long as one studies objects visible to the eye. But it is not adequate when studying very small (ultra-microscopic) objects like molecules. At that level, the wave aspect cannot be ignored. Still it has, largely not been considered in molecular biology, the basis of genetic engineering although it deals with ultra-microscopic objects.

The Nobel Prize laureates, Niels Bohr, Erwin Schroedinger and Brian Josephson are among the most famous scientists who have pointed out this deficiency of biological science. They have stated that no adequate knowledge of life processes can be acquired if the quantum physical aspect is not considered. Without such knowledge our understanding of the cellular processes probably remains incomplete and superficial.

In the last few decades increasing evidence has been gathered confirming that quantum phenomena are involved in key phenomena of life. Science is now taking the beginning steps in exploring this field, called "Quantum Biology". For more, see: Quantum phenomena in biology.

Conclusion

The cell is an incredibly complex structure performing a myriad of processes every moment that are finely attuned to each other under the tight and precise control of DNA. It is very incompletely known how DNA actually is able to manage all the innumerable cellular events in a co-ordinated and balanced way. Recent research indicates that important aspects of the cellular processes occur on a profound level, the quantum level, that has been very little studies so far.

As the knowledge about DNA and the nature of cellular processes is very incomplete, it is impossible to know what actually happens when DNA is manipulated. It is impossible not only to foresee what happens in the organism, but also what effects the release of artificially manipulated genes may have on the environment. This is the more serious as genes released into nature cannot be recalled.

There is ample experience from biology that manipulations of incompletely known complicated systems are invariably bound to have unexpected and potentially problematic results.

Jaan Suurkula M.D.

Related articles

• "Is our knowledge sufficient for safe use biotechnology?""  [EL].
• "Incomplete knowledge about DNA"  [ML]
• Pedagogical pages about cells, chromosomes and DNA [ML]
• Cellular organization [ML] A more advanced text about cells with good illustrations.