What Is DNA? Chapter 16th, The Nobel Laureates On Physiology Or Medicine In 2013, What Is Cell?(1)
What Is DNA? Chapter 16th, The Nobel Laureates On Physiology Or Medicine In 2013, What Is Cell?(1)
[ ইংরেজীতে প্রকাশিত করা হল কিছু কিছু বাংলাদেশী বংশোদ্ভূত বিদেশে অবস্থানরত ছাত্র পাঠকেরা যারা বাংলা ভাষা পড়তে পারেনা, তাদের অনুরোধে, দুখিত ]
The Nobel Laureates On Physiology Or Medicine In 2013.
Figure source- http://www.nytimes.com/2013/10/08/health/3-win-joint-nobel-prize-in-medicine.html?_r=0
From left: Randy W. Schekman, Thomas C. Südhof and James E. Rothman
1।Randy W. Schekman
Birth: December 30, 1948, St. Paul, MN, USA
2। Thomas C. Südhof
Birth:December 22, 1955, Goettingen, Germany
3। James E. Rothman
Birth: November 3, 1950, Haverhill, MA, USA
The Nobel Prize Organization declared the Nobel Award for the scientist-trio on Physiology or Medicine for 2013 on Monday, October 7.
Their discovery was upon cell function.
What is cell?
Cell is the basic alive micro unit of the body of living creature. An adult human body contains about 100 trillions of cells that grow from only one primary cell called Zygote in the uterus of mother।
It means that this big body of ours that contain 100 trillions of cells having extra ordinary power and capacity grew copying from only a microscopically visible cell through Mitotic division. (See figure-2) (To see Mitotic division see the chapter 6 & 7).
What did they discover?
Our body has always to produce innumerous types of chemical materials to operate the body. These chemical matters are produced inside a very micro factory called “Cell”.
What are these chemical substances? These are hormones, enzymes, neurotransmitters, signals, cytokines, antibodies etc.
The cell is not responsible only for synthesizing the chemicals.
Moreover the cell has also to transport the product from one organelle to another organelle inside the cell, one cell to another cell and sometimes also to a distant cell. To transport these, cell requires trucks of different sizes like small, medium or large sizes. The cell also does have those.
In some places cell requires shuttle trucks or trucks using in between carrier. The cell also has these.
Not only that, the cell also has bags as the businessman uses plastic bags to pack soybean oil to transport to remote stores, that is called “vesicle”
Moreover the cell has also to assure that the material can reach only to the remote target cell not to the non-target cell that is performed by a complex compound called “Receptor”.
Not only that, the cell has also to assure that the target cell can receive the material just time when it needs. If the target cell cannot receive the materials in time due to delay on the way for traffic jam, the cell would not be able to function and the body will collapse.
To avoid such hazards, the cell has set earlier arrangements since there is no guarantee that there would never occur traffic jam on the way.
To solve this problem, the cell stores the required product near the target cell somewhere nearby at a well-controlled and safe place in vesicles. And whenever the target cell requires the materials, brain transmits signal to release the materials from the vesicle to the receptor of the adjacent target cell.
If the cell would not arrange for instant supplying to the target cells while they require it in exact time, their emergent function would hamper, and the body would sick. The person would suffer from many complicated diseases like Diabetes, Parkinsonism, and Myasthenia gravis etc.
The brain cell performs this function.
This is why the cell assures that the target cells can receive the materials for their urgent work period.
This scientist- trio has discovered exactly this matter how the cell arranges to reach their product to the target cells promptly without any delay. They have also proved how this cell function is directly related to DNA function.
So, to understand their discovery, it is necessary to have some preliminary knowledge about cell beforehand or it may be difficult to understand their discovery clearly for some readers.
For this, I want to give some idea about cell earlier. Look today, how a simple cell operates its function. The specialized cells like heart cell, nerve cell, kidney cell, liver cell ctc. have also to do their own special functions despite their general functions just like an engineer or a doctor has to do their especial duties despite their general functions.
Now let us enter to the cell world and observe their strange functions.
Moreover, it will also be easier to understand if you revise the chapter 11 and see how the cell synthesizes protein through the organelle Ribosome and to the chapter 12 and see how DNA Mutation affects body functions .
A general animal cell-
Figure source- http://waynesword.palomar.edu/lmexer1a.htm
Figure-2, the cross section of a general (unspecialized)animal cell.
Our body is constructed by about 100 Trillion of cells. Each of them is as like as a complex world although they are microscopic-size. Not only that, our body has also 220 types of different specialized types of cells and each of this different specialized cell has different specialized type of function.
Look at the figure-1 above, a non-specialize cell. Look what it contains.
1) CELL MEMBRANE-(SEE FIGURE-1) - It is the outer covering wall of cell. The cell membrane protects the cell as like as our skin protects our body from various types of exposures. But the cell membrane not only protects the cell, but it has also to serve many types of important cell functions through it.
This is a semi permeable membrane through which the liquid of high and low density can pass and mix with one another via pressure gradient. The materials produced inside the cell are transmitted towards other cells very tactfully without rupturing the cell wall.
Very strange is not it!!
Yes, it is.
The materials are put into plastic bag-like vesicle that passes out perforating the cell wall causing no damage to the cell wall. Look at the figure-3 to see how they perforate the cell wall (5). These vesicles then travel towards and reach at their destination cell.
Then these vesicles enter the specified RECEPTOR of the target cell and transmit signal to the interior of the cell. Then the cell starts functioning according to the signal.
WHAT IS “RECEPTOR”?
Receptor is a specific type of protein compound on which only another specific type of compound can sit that can match to it. The compound can sit upon it is called “LIGAND”. The LIGAND attaching to the receptor sends signals to the cell and the cell then starts functioning according to the signal.
You can compare a Receptor with a lock and of a gate. Just like as if the appropriately matching key introduced into its appropriately matching hole of the lock, then the key can enter into the hole and can do its function upon the lock. Similar way, if a Receptor cannot find its proper key, it cannot allow entering into its hole and cannot produce any signal for work.
Or the specified messenger compound or Ligand (Ligand) holds the specified key for the specified Receptor.
So the cell can start work if the key of the messenger fits with the cell receptor.
It can be compared by the zippers of the both sides of a pant. One zipper works like a ligand and another one like the Receptor. If one zipper matches with the other one then work can start, otherwise not.
Various types of Receptors remain on a cell wall. Receptors also remain inside the cell and also in nucleus.(13,17)
So you can assume a Receptor as a locked gate of a cell.
What is the function of this gate?
Different types of gate are created for entering different types of materials. One can enter only through its own gate not through others’ gate. There is no way for one to enter through others’ gate.
Why one cannot enter through others’ gate?
Answer- everyone has different types of key for its own lock.
Who did create this specified lock and key?
DNA has created these different types of lock and key. Then the DNA has fixed these different types of locks as different types of Receptors.
Do you know what does then the DNA do?
when the DNA produces any material like hormones, enzymes etc. in cell, puts it into vesicles and sends to the specific target cells, at the same time DNA also hands over the specific key of that target cell Receptor directly to this vesicle, so that it can open the door when it arrives there.
Everyone must enter into its own door. One can never enter through others’ door.
DNA does never hand over one’s key to another one. If the DNA would make such error, the life would collapse immediately. But sometimes it occurs when DNA mutates, and then the person becomes sick. (for MUTATION see chapter 12.).
Did you see how intellect the DNA is!!
It is just like as, suppose you three emplo
yees work under a company in Dhaka city. Your boss asked you to go to Cox’s Bazar to perform some duties assigned individually for each of you. Your duties are of different types. Your boss asked you to stay there in separate rooms in a building and to work there separately. Each room is locked with different types of lock and has different keys. Only your boss has those keys.
Then your boss handed over the separate keys to each of you that match with your lock of the gate of your room only that you are assigned individually. In such case, one cannot enter others room. Each of you has to enter your own room and has to perform your individual types of duty there separately. One cannot hamper others duty.
You can understand now, how much the DNA takes care seriously to perform its complicated functions like this way nicely through its specific Receptors on cell wall supplying specific keys to each vesicle.
Yes, you can see how the vesicle enters its Receptor along with its materials unlocking the door and transmitting signals inside the cell, in figure 4 (7, 8, 9, 14).
What is that lock?
What is that key?
Yes, these are the subject of the discovery of this scientist-trio.
It will be cleared in next chapter.
Look the figure 3 below.
Fiure source- http://learn.genetics.utah.edu/content/cells/vesicles/
Figure-3, the cell wall.
Look here how the vesicle containing material perforates and comes out of the cell wall to transport the content to nearby or distant cell. There, it will enter into Receptor and perform the necessary work.
Now look how this vesicle enters the cell Receptor and works through transmitting signals inside the cell in figure 4.
Figure source- http://hubpages.com/education/How-drugs-act-tyrosine-kinase-receptors-hormone-receptors
Figure-4, Receptor working on cell wall.
Look here, how the cell wall transmits signal for working inside the cell via Receptor.(14)
Thus far, only the cell wall has been described. Now the other micro parts of the cell will be discussed (See figure-2)
2) CYTOPLASM- The greater jelly like part that resides in between the cell wall and nucleus is called Cytoplasm or Cytosol.(12)
3) Nucleus- The dense round part surrounded by a wall at the center of the cell is called Nucleus. Inside the Nucleus there remains another round part without wall is called Nucleolus. The Nucleolus synthesizes Ribosome and RNA.
This is the Nucleus which contains our most important substance the 23 pairs of Chromosome that controls all the functions of our body.(12)
4) Mitochondrion-A lot of Mitochondria remain inside the Cytoplasm. Mitochondria produce energy for the survival of the body and for our activities. Energy is stored in the form of a chemical compound called ATP or Adenosine Triphosphate. Despite cell’s DNA, mitochondria have also own DNA that they can divide themselves. The food that we eat and digest is used as raw materials for producing energy.
5) Ribosome- It is a micro unit organelle having no wall remains inside the Cytoplasm. Its function is to synthesize protein according to the instruction given by the DNA to operate body. DNA synthesizes all the protein of the body here, and then transmits them through Endoplasmic reticulum, Golgi apparatus and vesicles to the target cells. It can move inside the cytoplasm freely and work in together with Endoplasmic reticulum residing side by side (12). See the chapter 11 how Ribosome works.
5) Endoplasmic reticulum (ER)- there are 2 types, Rough ER and Smooth ER.
The Rough ER remains in-touch with Ribosome. It helps synthesizing membrane and secretory proteins like enzymes and hormones. It also helps in synthesizing antibody in WBC, and hormone Insulin in Pancreas.
The Rough ER and Smooth ER remain in-touch with one another.
Smooth ER has also many functions. It helps producing carbohydrates and fats. The materials produced in Rough ER, are carried first at Smooth ER within vesicles(plastic bag like container). For this, this vesicle is called the Transitional Vesicle.
It is just like, as we pack the materials before we pick up on a platform and load on goods- carrying train.
The ER in liver cells produces an enzyme that de-poisons the action of some poisonous chemicals.
The ER in brain cells produces male and female hormones. (11).
6) Golgi apparatus- It looks somewhat like Pancake. The Transitional vesicle prepared in ER enters into Golgi perforating its wall (see figue-3). Then the materials inside the vesicle enlarged and folded inside the Golgi. Now this material is packed into a large vesicle.
This large vesicle is now called the secretory vesicle. It now emerges from the Golgi at the opposite side where there remains cell wall. (Figure-3).
The Secretory vesicles now cross the cell wall and start for their own destination.
How these vesicles cross the Golgi and cell wall?
They cross just like budding without making any hole on the wall. How do they perform it? See figure-3 above (5).
7) Cytoskeleton- it is some micro fiber like substance inside the cell. It supports to hold the shape and size of the cell. It helps cell division and cell movement (see the chapter 6, 7, . It is also used as truck line for the movement of organelle from one place to another place inside the cell. (12)
Lysosome and Peroxisome – Cell uses these organelle as dustbin, digesting and detoxicating organelle. They digest if any microbe enters inside the cell. They also de-poison if any poison material enters inside the cell. The cell throws its waste product into it (12).
Then the Lysosome keeps the cell healthy digesting them in particular a tri-sugar fat named Globotriaosylceramide with the enzyme Alpha-galactosidase A. A gene called “GLA” produces the enzyme Alpha-galactosidase A. The cytological location of this gene is Xq22. If this gene is mutated the cell becomes sick depositing fat inside. Then the person is attacked with a disease called Fabry. This disease can attack any organ like heart, liver, and kidney ctc. (15)
9) Vacuoles- it balances the internal pressure of the cell. It collects the waste products of cell and emerges outside. It also maintains PH of the cell inside.(13)
The chapter is shortened here so that it would not harden the readers if lengthened more. And it is also not possible to discuss al things here. Those who want to learn more can see the references.
Keep in- touch to know the mystery of human body.
See the other chapters here- https://dnaandthemystryofhumanbody.wordpress.com/
UPDATED ON- 1/11/2016
References of chapter 16th.
Nobel prize org.
2. Science Daily
4.function of cell wall
5. FUNCTION OF VESICLESS
10. ANATOMY OF NUROMUSCULAR JUNCTION
11, ENDOPLSMIC RETICULUM