A Unique Creation: Self-Replication of DNA

As we know, cells multiply by dividing. While the human body is initially composed of a single cell, this cell divides and reproduces itself many times over in a ratio of 2-4-8-16-32...

What happens to DNA at the end of this dividing process? There is only one DNA chain in the cell. However, it is evident that the newly formed cell will also require a DNA. In order to fill this gap, DNA completes an interesting series of operations, every phase of which is a different miracle. Finally, soon before the cell divides, it makes a copy of itself and transfers this to the new cell.

Observations of cell division show that the cell has to reach a specific size before dividing. The moment it exceeds this particular size, the division process automatically starts. While the shape of the cell begins to get smoother so as to accommodate the division process, DNA starts to replicate itself as mentioned earlier.

This means that the cell "decides" to divide as a whole and the different parts of the cell start to act in accordance with this decision. It is evident that the cell is devoid of the consciousness to accomplish such a collective action. The division process starts with a secret order and the entire cell, including DNA, acts on this order.

First, DNA divides into two to replicate itself. This event takes place in a very interesting manner. The DNA molecule which resembles a spiral ladder divides into two like a zip from the middle of the rungs of the ladder. From now on, DNA divides into two portions. The missing halves (replicates) of both of the two portions are completed with the materials present in the milieu. In this way, two new DNA molecules are produced. In every phase of the operation, expert proteins called "enzymes" that function like advanced robots take part. Though it seems simple at first sight, the intermediary processes taking place throughout this operation are so many and so complicated that to describe the whole event in detail would take pages.

One thing must not be forgotten here. The enzymes that form as a result of atoms coming together examine one half of the DNA spiral, identify those parts that are missing, take the missing parts from the appropriate places and add them where needed. In this way, the copying of DNA comes about. The way that tiny unconscious, unreasoning structures can flawlessly carry out such complex processes, that require consciousness, knowledge and reason is not to be glossed over by just reading about them. There are important truths revealed here that need to be considered.

The new DNA molecules that emerge during replication are checked repeatedly by inspector enzymes. If any mistake is made-which can be quite vital, it is immediately identified and corrected. The erroneous code is removed and replaced by the correct one. Although all these processes take place at such a dazzling speed-3,000 base pairs are produced in a minute,-all these pairs are checked repeatedly by the enzymes in charge and the necessary amendments are made.

DNA synthesis begins at a specific base sequence, known as the origin of replication. Here, DNA strands are separated by an enzyme known as DNA helicase, following which single stranded DNA binding proteins attach to the unwound strands, preventing them from winding back together. At the same time, an RNA molecule known as RNA primer is synthesised between the strands as they detach themselves. This molecule helps DNA polymerase read nucleotides and initiate replication. DNA polymerase binds to one strand of the DNA, reads the sequence of bases on the template strand and then synthesises the complementary strand. Thus, it reforms a double helix. DNA synthesis proceeds on both single strands in opposite directions. When the process comes to an end, two new daughter molecules emerge, each containing one newly synthesised strand.

Thanks to the information within DNA, the proteins that undertake countless tasks in our bodies are produced with all the features they need.

The following facts, which are particularly revealing will give a better understanding of the great speed at which DNA multiplies. The division of one cell lasts between 20 and 80 minutes, and the information on DNA needs to be copied and multiplied within that time scale. In other words, the 3 billion pieces of information in DNA can be copied in between 20 and 80 minutes with no faults or omissions. That is as miraculous as the perfect reproduction in such a short space of time as all the information in a library, or 1,000 books, or a million pages. And note carefully, it is not technological equipment or advanced photocopiers that do this, but enzymes formed by collections of atoms.

In the newly produced DNA molecule, more mistakes can be made than normal as a result of external factors. In this case, the ribosomes in the cell start to produce DNA repair enzymes as per the order given by DNA. Thus, as DNA protects itself, it also guarantees the preservation of the generation.

A special enzyme, called telomerase directs the replication of telomeres. Telomere is the end of a chromosome, which consists of repeated sequences of DNA that perform the function of ensuring that each cycle of DNA replication has been completed.

The cells are born, they reproduce and die just like human beings. Yet the life spans of cells are much shorter than the life of the human they constitute. For instance, the majority of the cells that used to make up your body six months ago do not exist today. However, you are now able to survive because they have divided on time to leave their places to the new ones. For this reason, highly complex operations like multiplication of the cells and replication of DNA are vital processes which cannot tolerate even a minor mistake when it comes to man's survival. However, the multiplication process runs so smoothly that the rate of error is only one in 3 billion base pairs. And this one error is eliminated by the higher control mechanisms in the body without causing any problems.

The most interesting point is that these enzymes which help in the production of DNA and control its composition are actually proteins produced according to the information coded in DNA and under the command and control of DNA. There is such an intertwined, perfect system at work that it is by no means possible for such a system to have attained this state by gradual coincidences. Just as DNA has to exist for the enzyme to exist, so the enzyme has to exist for DNA to exist, and for both to exist, on the other hand, the cell has to exist completely, down to its membrane and all the other complex organelles it contains.

DNA repairs itself and permits no errors. When the DNA synthesis is complete, an error occurs in one nucleotide in a thousand. Yet such errors have been prepared for. There is a special group of enzymes charged with repairing errors that occur during the DNA synthesis. These enzymes identify the error in a conscious manner and remove the defective nucleotide. They synthetise a new nucleotide and insert it back during the process.

All through the day, quite without your being aware of it, numerous operations and controls are carried out, and many measures are taken in your body in an incredibly fastidious and responsible manner so that you may lead your life without any problems. Every single thing carries out its duty successfully and completely. God has placed at your service countless atoms and molecules, from the biggest to the smallest, from the simplest to the most complex, so that you may live a good and healthy life. Such favour and blessing alone are enough to deserve our constant thanks.

It was God who made the night for you to rest in, and the day to give you light. God pours out His favour on mankind, yet most people do not give thanks. (Qur'an, 40:61)

Many enzymes have to exist alongside DNA during replication and protein synthesis. The red and yellow areas in the picture show enzymes that work with DNA.