DNA (deoxyribonucleic acid) is a highly complex molecule and holds the key to the secret of life.
To carry out its function of creating and sustaining life, it requires another set of complex molecules, proteins. Understanding how DNA and proteins work at a cellular level, it is useful to compare the human body to a house although it is much more intricate. While DNA may be considered to be the plan of what the design of the house should be, the proteins are like the building material and the workmen to construct the house. Similarly, DNA present in our cells contains the information how to build a human body from scratch while the proteins are the building blocks of bone, muscle, nerves etc and carry out functions such as regulating blood sugar, transporting oxygen in the blood, protecting us from infections, making us smile, swallow, digest food and many more.
THE AMAZING DNA
Precisely how does DNA accomplish its mammoth task of storing billions of bits of information and how does it control protein activity of which there are 200 000 different types. Unlocking its mechanism means venturing into the heart of the cell where DNA resides. Inside the nucleus of the cell there are 46 chromosomes of which 23 come from your mother and the other 23 from your father. Chromosomes are made of long strands of DNA. DNA is present in almost all of your 10 000 trillion cells and each cell (about 200 times smaller than a millimetre), contains two metres of densely packed DNA. Disentangling all your DNA (collectively known as the genome), and stretching it out, it would cover a distance of twenty million kilometres. According to Francis Collins, head of the genome project, a live reading of the entire genome (all the DNA in your 46 chromosomes) at a rate of one letter per second, would take thirty one years.
STRUCTURE OF THE DNA
The most pressing issue in the mid 1900’s was to determine the chemical structure of the DNA molecule i.e. the internal arrangement of its constituent atoms. The architecture of DNA was finally unravelled in April 1953. Francis Crick and James Watson presented to the scientific community a 3-dimentional picture of the overall structure of their interpretation of the DNA molecule. DNA is described as double helix, like a spiral staircase or twisted rope ladder. The two arms of the ladder are made of recurring sugar phosphate units and each step of a base pair. There are four of these bases known as guanine, cytosine, thymine and adenine abbreviated GCTA (see figure). What is remarkable of these bases is the manner in which they combine with one another; A on the one strand always pairs with T on the other strand, and G always with C. Human DNA contains about 3.1 billion of such base pairs.
A SEGMENT OF DNA SHOWING BASE PAIRING
Run your eyes down the left arm of the ladder. Looking from top to bottom, the order of the bases is GAGTA. This is known as the base sequence and describes the DNA molecule; a particular DNA is recognised by its specific base sequence. We humans share 99.9% of this base sequence since we belong to the same species. But we are not identical hence the 0.1% difference.
The unique base pairing system enables DNA to make an exact copy of it self since each strand can act as a template for the production of a new one. This is exactly what happens in nature when DNA divides. Enzymes split the DNA molecule (in steps) in the centre separating the bases on the one strand from their corresponding partners on the other strand. With the help of enzymes again, bases obtained from the cellular soup are attached to the exposed unpaired bases on each of the separating DNA strands. As always, G latches on to C and T on to A. In this way two new strands are formed, each complementary to the parent strands. While you started off with a single DNA, you end up with two identical to the parent molecule.
HOW DOES DNA SUPERVISE PROTEIN ACTIVITY?
To rephrase, how is DNA information translated into protein information? Just like DNA owes its uniqueness to the specific arrangement of its bases on its strands (its sequence), so protein individuality depends on the order of the amino acids on its chain (a protein is a chain of a large number of amino acids). There are twenty amino acids, but joining them up in different combinations is more than sufficient to account for the thousands of different proteins. DNA directs protein synthesis in the following manner: Three neighbouring bases on one of the DNA strands represent the code to make a certain amino acid. For example, the triplet code GCA may be the code for amino acid X, another combination, say ATA, the code for amino acid Y and so forth. It follows that a group of adjacent triplets specifies a particular sequence of amino acids i.e. a specific protein. The segment of DNA doing this is called a gene. DNA can therefore be divided into genes, each gene containing a code for a particular protein (several genes may however be involved in constructing a protein). It is helpful to think of DNA in terms of letters, words and sentences. Individual bases may be thought of as letters whereas the codons are likened to words (each triplet combination example GAT represents a word). Larger sections are like sentences; the meaning of the sentence (the genetic instructions) depends on the order of the words i.e. the sequence of the triplet codes. Chromosomes are like book volumes of information.
Just using four bases in various triplet combinations, 64 combinations are possible, enough to specify 20 amino acids. Varying the sequence of the amino acids thousands of proteins can be manufactured. This simple but elegant code system explains the formidable information-carrying capacity of DNA and how information is transmitted from one cell to another. It is ultimately the DNA that determines the species type and their members’ individual differences. You are human because of human DNA; chimps have chimp DNA and plants have plant DNA. Through DNA cells somehow conspire so that trillions of them come together in a cohesive unit and look and behave like human beings, elephants, plants – an astonishing concept.
DNA IN THE QURAN
Several points were highlighted in the above discussion. To summarize:
- DNA is shaped as a spiral staircase or twisted rope ladder.
- Its unique base pairing system-adenine always binds to thymine and guanine to cytosine. This base pairing rule enables the one strand of the DNA to act as a template for the creation of a new matching strand. In this way DNA can reproduce making exact copies of itself which in turn enables it to transmit information from parent to daughter cells.
- The translation of DNA information into protein information through a code system explains how DNA regulates protein synthesis and
- It is ultimately DNA that determines the design of the body of the organism and hence the species type.
DNA is referred to in the Quran in the following verse: “O mankind! Be conscious of your Sustainer’s (knowledge) Who evolved you out of a single (stranded DNA type- molecule) and from a similar (molecule) evolved its complementary partner; And from the (complete) pair (through repeated replication) multiplied you into large numbers of men and women” (4-1). Commentators influenced by the Adam and Eve creation story have loosely translated the word nafs (an Arabic word which occurs in the Quran) as self, soul or spirit, meaning man was created from a single soul which is devoid of sense. The most appropriate translation of nafs in the above verse is its other meanings, life essence or vital principle. The latter is defined as the chemical constituents of the earth which I have further interpreted as DNA or RNA for the following reasons. It is plausible from the context and definition of vital principle that the proposed DNA (or RNA-molecule) must be a complex chemical entity that evolved from the fundamental elements of the Earth through gradual chemical build-up. This is supported by other passages in the Quran which state that complex life on Earth evolved from simpler units on the Earth: “He evolved man from water” (25-54), “He evolved man from an extract of clay” (23-12), “He evolved man from the chemical constituents of the Earth arranged in layers” (40-67). Verse 4-1 above states that the complex chemical entity emerged as a single (stranded) complicated molecule; its corresponding partner evolved subsequently or perhaps concurrently from a similar molecule. The two chains linked up forming a double stranded self-replicating molecule – DNA.
Let us develop the interpretation of vital principle as DNA. Remember vital principle is defined as the chemical elements of the Earth. Both living and non-living matter are made up of the same atoms, like carbon, nitrogen, oxygen, iron, and so forth. How does non-living matter become alive? When ‘dead’ atoms combine in the right manner and create life, it must at some stage or stages during the process switch from non-life to life. The critical transition step or steps are most likely reached at the DNA level. Why? Along the continuum of existence moving from simplicity to complexity, the simplest chemical structure which reveals the first identifiable signs of life (replication and reproduction), but still lacking its higher essential attributes (energy production, reaction to stimuli, locomotion), is DNA. Based on this understanding and the fact that it is at the heart of all cellular activity, DNA is the best candidate for representing the transition stage from non-life to life (it is the vital principle), and hence my rendering nafs as the DNA molecule. The word multiply in the above verse supports this interpretation. The property of multiplication or replication is a pivotal ingredient of cumulative selection (gradual development) which is one of the principle mechanisms of evolution.
Let me briefly explain the concept of cumulative selection.
During evolution species do not appear from another in a single step, but there is a gradual step by step cumulative transformation. Normally as stated DNA replication is carried out with stunning accuracy so that daughter copies are identical to the original. However, sometimes a copying error occurs which is called a mutation. The wrong base is inserted into the newly manufactured DNA strain so that the triplet code is altered and a different amino acid is added to the growing protein chain. In most cases such a protein is dysfunctional. But occasionally the modified protein improves adaptation for instance giving rise to sharper teeth or an improved camouflage. If the beneficial mutation ends up in the sex cells of the affected organism, its off-spring who inherits the altered gene is more likely to survive and reproduce successfully and eventually become the dominant form. It is conceivable that a series of such adaptive mutations over many thousands of years will slowly change the organism and produce a new species. Remember that DNA is a set of instructions that determines the features of an organism. It follows that a number of mutations (changes in the DNA sequence) may lead to a change in the design of an animal. It is the property of replication of DNA which through cumulative selection creates complexity and the formation of new species.
The word ‘evolve’ in the above verse means to fashion, shape and adapt, and such changes are controlled by the genetic material, i.e. DNA. It is DNA that is the main replicator which underlies cell division and all ongoing evolutionary processes.
Let’s further develop our evidential argument to show that the Quran really does describe the DNA molecule. Consider the following verse: “He it is who creates1 man from a minimal quantity of (sperm2) liquid, then lays down the (genetic) plan3 which would decide its (future) features and (embryonic) stages” (80–19). The interpolation of ‘sperm’ in this verse is justified by another verse: “Was (man) not a small quantity of liquid sperm which has been poured out?” (75–37). The small volume of liquid is clearly identified as sperm.
|1. Khalaqa – to bring into existence according to measure (referring to ‘creates’ in 80–19).
2. Nûtfa – droplet, minute quantity of liquid (referring to ‘sperm’ in 80–19).
3. Qaddara – to exercise thought in arranging and preparing a thing or affair (to plan or programme); decide its stages; to measure or determine its quantity , size , correct relation of parts to one another or to a point a particular time for it (referring to ‘plan’ in 80–19).
The word ‘nutfa’ in 80-19 can be interpreted as the fertilised egg derived from following three verses: Verse 7–189 states: “When he embraces her and she conceives (what is at first) a light burden, and continues to bear it (unborn child).” This verse states a biological principle: conception requires the involvement of both male and female. Note the phrase ‘light burden’. Many women experience mild abdominal discomfort with ovulation and implantation. Verse 86–6 states: “He creates man from a mixture of fluids emitted from between the genitals (of man), and the pelvic arch (of a women)”. The essence of sexual fluid issues from the testes in the male and the sexual organs situated in the pelvis of the female. The production of a new individual, which requires the participation of both male and female, is also expressed in 76–2: “Surely it is We that created man from a drop of sperm intermingled (with the ovum)”. The bracketed phrase is deduced from the previous two verses. Verse 80–19 also conveys the principle that the fertilised egg contains the genetic plan, which is a set of instructions or, in fact, DNA. DNA governs embryonic processes and determines the features of the individual and, therefore, of the species. If cells divide as stated in the following verse: “Have you considered the seed that you sow in the soil? Is it you who causes it to grow and divide or is it Us?” (56-64), which is complemented by a 7–189: “It is He who originated and evolved you from a single living entity”, then the DNA must also divide to ensure that it is present in the descendant cells. This division of the DNA allows information to be transmitted from the fertilised egg to the descendant daughter cells, so that these new cells can continue their vital functions. Therefore, in order to carry out these functions, DNA must have the ability to replicate and carry information.
Consider the following verses: “(Thy Sustainer is He) who originates (every living thing); thereupon forms and proportions1 it symmetrically with a just adaptation of its body parts to the performance of its functions. He who determines the nature2 (of such living things) and evolves3 it in accordance with that nature” (87-2, 3).
|4. Fasowwâ: From the root ‘sawiya’ – to fashion, to shape, to make uniform or symmetrical; to fashion in a suitable manner; just adaptation of its component parts, to adapt creation to the exigencies (performance of its functions) or requirements of wisdom.
5. Qaddara: From the root ‘qadara’ – to compute or determine the quantity, size, mass; measurement (hence the interpretation as nature).
6. Hadâ – to guide or determine the evolutionary path of a thing, which is intimately linked with its peculiar qualities.
This verse speaks of fashioning and shaping living organisms so that their body structures suit the functions they are meant to perform. In short, the verse refers to the process of adaptation, which is fundamental to evolution.
Verse 80–19 mentioned earlier states that DNA dictates body design. But, according to 87–2 and 3 the organs that undergo adaptation are being constantly reshaped and resized. Therefore, the conclusion is that in order for a body to change and adapt, its DNA must continuously change as well – in other words, it must mutate.
The only molecule that reveals these features (a paired structure and the ability to replicate, transmit information and mutate) is DNA. An interesting fact is that if DNA determines the features of an individual (80–19) and if these features are unique for every person, then his or her DNA also must be unique. This special feature of DNA deduced from the Quran is an indispensable tool in modern forensic science.
My insertion of knowledge in verse 4 -1 above is based on the context and the Quranic principle that DNA (and atoms, gravity, space-time, energy, mutations, the whole shebang), is not nature’s invention, but the outcome of divine ingenuity.