We perceive several problems related to the functions in many situations in life and develop solutions accordingly. The function shows the effect of one (or more) variable(s) on another variable. In simple terms, one factor can be called the transformation of another factor. When you send a piece of mail by cargo, you pay according to the weight of your cargo. Or imagine using an hourly Internet service in a library or airplane; the more hours you use the Internet, the more you pay.

A group of people want to rent a bus. The number of people does not affect the cost of rent for a bus. However, the cost per person could change depending on of the number of people. The more passengers, the less fee they pay for each passenger. Conversely, if the number of passengers is less, the cost of the bus fee could be more.

The examples are given above help to understand the mathematical function more easily. We perceive several problems related to the functions in many situations in life and develop solutions accordingly. The function shows the effect of one (or more) variable(s) on another variable. In simple terms, one factor can be called the transformation of another factor.

Consider shipping by mail. There are actually two situations here; the weight of the cargo sent and the amount of money paid based upon the cargo’s weight. This gives us a hint for the payable amount. For example, we may know how many pounds of cargo can be sent for $10. We also may calculate how much money is needed to ship 5 pounds of cargo. We can formulate this shipping problem:  Let x be the weight of the cargo and let y be the amount to be paid. In addition, for each parcel sent, including taxes, let us assume that it costs $3. In this case, we get an equation such as y = 2x + 3. Here, the number 2 given in front of the variable x is the money paid per pound. We calculate how many dollars we will pay for a 4-pound cargo: (2×4) + 3 = $11. If 2 dollars per pound is received, a 4-pound package shipping fee is 11 dollars.

Another example would be the use of the Internet. If 40 cents is requested per hour, $1.2 will be given for 3 hours of internet usage. Thus, the equation can be written as y=40x, where x is internet usage time per hour, y is amount to be paid.

The bus rental example is slightly different from the above two examples. Although this example specifies the function, this time there is a reverse situation. In the first two examples, like (x or) input increases, (y or) output will increase. In the case of bus rental, the bus rental fee is fixed and as the number of passengers increases, the payment per person will decrease. Let’s say $400 is required for the daily rental of a bus. 40 people pay $10 per person while 8 people pay $50 per each person.  This equation would be; y=400/x, where x is the number of people, y is the amount of money paid per person. Functions are important in understanding the relationship between two variables.

Life is a function. In mathematics first, what is the function in its simplest form? Let us give the known definition in schools.

Function: Let A and B be two sets different from the empty set and there is a relation f from set A to set B. If the relation f associates each element of the set A to one and only one element of the set B, this relation is called the function from set A to set B. It is shown as f: A→B or A→B. A is called the definition set of the function and B is called the set of values. A set of elements that match the elements of set A in set B is called the set of images of the function and is denoted by f (A).

In this case, if we clarify the definition a little, a relationship from A to B to be defined in order to function f; the following conditions must be met:

1. There should be no elements in the definition set that do not have an image. However, the element can remain exposed in the value set.
2. Each element in the definition set must not have more than one image.

Let us try to find the reflections of the definition in our lives. We assume that A is the world in which we live. If we say “World” for Set A (Definition Set), we would call Group B “the Afterlife” (Value Set). Because there is a connection from this world to the other world. We will see our values in the afterlife against what we do in this world. As someone who fits the definition of a “good” person will be of high value, the definition of a “bad” person will consequently result in a lower value. So, set A considers the world and its elements as ‘living people’. We can think of all the people in the world and include them in this group since life is finite for all of us. The mathematical meaning of this reality is the following:  all elements will be moved from set A to set B (Let A and B be two sets different from an empty set and a relation f from set A to set B.). There is such a connection (or relation) that one who leaves the world cannot go to two places at the same time. Destinations are clear: abode of reward or abode of punishment. We will all be eventually placed into one of these two groups. In some cases, the last stop of the people will be paradise, even if there are those who go to hell first and purify their sins. Consequently, in the last case, no one will be in two places at the same time (If the relation f associates each element of the set A to one and only one of the set B, this relation is called the function from the set A to the set B).

Just because everyone has one final destination does not mean that that destination can only hold one person. If the levels of Heaven and Hell are considered correctly, it is possible that there is more than one person for each level or that no one has come to that level. It is possible that there are those who have sinners at the same level. We can speculate that there may even be such a level that is inaccessible to all people. The Creator creates such places in order to show His grace, mercy, and power. (In the definition set, there should not be any elements without an image. But in the value set, there may be exposed elements.)

Life itself is a function. God created life according to certain rules. We should do our best to explore, find, and use these rules. Seeing the beauties of life and being amazed by the astonishment and capturing happiness in both worlds is achieved by seeing the manifestations of God everywhere.

It is worth contemplating that humans are in need of microorganisms to survive and that living things as insignificant (!) as bacteria are necessary to synthesize B12 vitamin. Why our so-called bacteria ancestors (!) from which we evolved – as some claim – lost this ability to synthesize B12 vitamin which was, and still is, vital for survival, is a challenging question for those scientists who support the theory of evolution.

The journey of B₁₂ in our body

Cobalamin, which is taken in with food, is absorbed by the final section (ileum) of the small intestine and transported into the blood by receptors on the cell membrane. For B12 to be absorbed into the blood, it is necessary to have an “intrinsic factor” bound to this vitamin. The intrinsic factor is a glycoprotein produced in parietal cells that secrete gastric acid. After the absorption, the vitamin binds to transcobalamin, a carrier protein found in the blood, and it is then being bound with transcobalamin II so that it can penetrate the cells. B12 can be stored in the liver to meet the needs of our body for a long time. A deficiency in cobalamin due to a poor diet (e.g., vegetarians) or a failure to produce the intrinsic factor in the stomach may result in pernicious anemia, which is fatal. Cobalamin deficiency negatively affects DNA synthesis, which is necessary for production of new cells, particularly in the division of the stem cells that are assigned to construct new red blood cells. This is followed by the circulation of cells that will generate underdeveloped red blood cells; these cells will not be able to function properly and will have larger diameters.

The training of parietal cells

If the stomach is removed or cannot produce the intrinsic factor, it is impossible for B12 to be absorbed. It is worth reflecting on the wisdom of why an organ like the stomach, the main duty of which is to partially digest food and convey it to the intestines, synthesizes intrinsic factor. How can the stomach know that our body is in need of this protein? How did it become able to synthesize this very special composition of glucose and protein which is so necessary to absorb intrinsic factor through the gastrointestinal tract? Why doesn’t our body produce the vitamin in the first place, instead of binding it to such a complex molecule? And how do the parietal cells know what is necessary to bind this vitamin, the use of which they cannot understand, although they have never been trained in bio-chemistry, physiology, or pharmacology? In which laboratory did these cells synthesize and test this compound?

The intrinsic factor

In order to decompose proteins into amino acids, the stomach secretes hydrochloric acid and an enzyme called pepsinogen. Parietal cells that secrete acid also produce a protein (intrinsic factor) which is not damaged by the acid or the pepsinogen enzyme. How were these cells able to develop a synthesis in which proteins do not decompose, which can protect them from the acid in the stomach, and bind themselves to a vitamin like B12, which is absorbed only in very small quantities?

The hydrochloric acid secreted in the stomach is like bleach and it irritates anywhere that it goes other than the stomach. Should even the slightest quantity of this acid pass into esophagus (reflux, diaphragm boiling) it can cause severe burning. It is amazing that B12 is found and bound in a cauldron like the stomach, but is not damaged by the acid produced when the stomach is filled with food and drink.

The intrinsic factor bound with the vitamin goes on its journey and it reaches the absorption region in the last section of the small intestines. During absorption, the gates on the cell membrane of the intestines open up only to allow the B12 intrinsic factor compound. Maintained in the intestinal cell for a while, the B12 vitamin binds to the transporter transcobalamin and is conveyed to the cells through the blood. After reaching a cell, the vitamin, needed by the entire body, is bound to another transporter: transcobalamin II.

Some components, although they appear to be very simple, must be supplied from outside our bodies if we are to survive. B12 vitamin is one such component, and it certainly deserves to be studied well.