Cell Division – What, When and How? [Facts]

In this article, we will discuss cell division in a simple and easy way and also look at interesting facts related to it, so stay tuned till the end of this article.

To understand cell division it is necessary that you have a good understanding of the cell, for a better understanding of the cell, you can read the given article.

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What is a Cell?

Cells are the basic building blocks of all living things. The human body is made up of several trillion cells. Cells provide a structure to the body. Cells also contain the body’s hereditary information (what we call DNA ) and can also make copies of themselves.

There are many such organisms, which are made up of only one cell, they are called unicellular organisms such as bacteria. And such organisms which are made up of many or many thousands, millions, millions or billions of cells are called multicellular organisms, such as plants and animals.

Most plant and animal cells are visible only under a light microscope, which ranges in size from 1 to 100 micrometers. (1 micrometer i.e. one millionth of a meter).

Also read – Basics of Cell in Hindi

What is cell division called?

When the skin is cut or peeled, we see that it refills within a few days and becomes the same as before. That is to say, in our body every day, every hour, one of the most important events of life is happening i.e. our cells are dividing.

When cells divide, they form new cells. A single cell divides to form two cells and these two cells divide to form four cells, etc. This process is called “cell division “ or “cell reproduction”.

Overall, new cells are formed when old cells divide. This ability of cells to divide is unique to living organisms. Because if it were not for this then life would not be possible the way it is now.But the question comes that why does the cell keep dividing?

Also read – Difference between prokaryotic and eukaryotic cells [illustrated]

Why does the cell divide?

Cells divide so that living things can develop. It is one of the basic things that living organisms have got by nature by default. When organisms grow, it does not mean that the cells are getting bigger. Rather organisms grow, as cells are dividing to produce more and more cells.

You can guess what the scale of cell division is from the fact that about two trillion (two trillion) cells divide daily in the human body. When it gets divided so much, then the question is, then how many cells are there in our body?

We all start out as a single cell, (what we call an egg) and by the time we’re adults, our bodies have trillions of cells. Although this number depends on the size of the individual, biologists believe that this number ranges from about 37 to 40 trillion .

Also read – DNA Test [Genetic Testing]: What, How, Meaning and Benefits..!

How do cells know when to divide?

In cell division, the cell that divides is called the parent cell. This parent cell divides into two daughter cells. Then this process repeats, which is called the cell cycle .

Cells control their division by communicating with each other using chemical signals from special proteins called cyclins. These signals act like switches to tell cells when to start dividing and when to stop dividing later.

As important as cells divide, it is equally important for cells to stop dividing at the right time. If a cell cannot stop dividing, it can lead to a disease called cancer.

Some cells, such as skin cells, are constantly dividing. We constantly need to make new skin cells to replace the skin cells we have lost. Did you know that we lose 30,000 to 40,000 dead skin cells every minute?

This means that we lose about 50 million cells every day. It is also worth remembering that nerves and brain cells divide very rarely.

Also read – DNA and RNA [DNA and RNA]: Differences and Similarities

How do cells divide?

Depending on the type of cell, cells divide in two ways – mitosis and meiosis . Each of these methods of cell division has special characteristics.

In mitosis, a single cell divides into two cells that are replicas of each other, and have the same number of chromosomes. This type of cell division is good for basic growth, repair and maintenance.

In meiosis, a cell divides into four cells that have half the number of chromosomes. Half the number of chromosomes is important for sexual reproduction, and provides genetic diversity.

Let us understand both types of cell division [ mitosis and meiosis ] in detail;

Mitosis Cell Division

First we have to understand that somatic cells and reproductive cells are different. Somatic cells make up most of the tissues and organs of our body, including skin, muscles, lungs, intestines, and hair cells. Whereas reproductive cells make eggs.

What is meant to be said here is that mitotic cell division divides somatic cells and not reproductive cells.

In mitotic cell division , each of the daughter cells has the same number of chromosomes and DNA as the parent cell. The daughter cells produced by mitosis are called diploid cells.

Diploid cells have two complete sets of chromosomes. Since daughter cells contain exact copies of their parent cell’s DNA, no genetic variation is created through mitosis in normal healthy cells.

कोशिका विभाजन — Credit – Arizona state university (Askabiologist)

The Mitosis Cell Cycle

Before a cell divides, it is in ” Interphase “. There are 2 trillion cell divisions in our bodies every day, but each cell actually spends most of its time in interphase.

In fact, interphase is the period when a cell is getting ready to start dividing. During this time the cells are collecting nutrients and energy. Also the parent cell is making a copy of its DNA so as to be shared equally between the two daughter cells.

The process of mitosis consists of several phases of the cell cycle—interphase, prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis. As can be seen in the picture below;

Prophase is the first official stage of mitosis. Remember, the parent cell has already copied its DNA during interphase. During prophase, chromatin in cells,condense or gather together in preparation for cell division. By compaction, DNA and chromosomes can be more easily controlled to prevent mistakes during cell division.

Prometaphase – When chromosomes condense, the nuclear membrane and nucleolus begin to break down and disappear. This makes it easier for the cell to divide all its components equally. At the same time, centrioles,The filaments begin to migrate to opposite ends of the cell and elongate.

Metaphase – When cells reach metaphase, the spindle fibers from the centrioles are fully elongated. The spindle fibers draw the chromosomes in a line in the middle of the cell. Each chromatid is attached to a spindle fiber at the opposite end of the cell. This sequence of chromosomes is important in ensuring that each new cell that is formed will have the same and equal number of chromosomes.

Anaphase – Now that the chromosomes are well lined up, they are ready to separate. In this phase the chromatids (half of the chromosomes each containing the same information) begin to travel in opposite directions and new daughter cells are formed.

Telophase – In this phase, the chromatids now move to opposite ends of each other. The fibers from the centrioles tend to retract or break off and disappear as soon as division begins. In addition, a new nuclear envelope is formed around each set of chromosomes.

Cytokinesis – Cytokinesis is the final step of mitotic cell division and occurs when proteins in the middle of the cell begin to pinch the larger cell into two separate cells. Each of the new cells are now identical copies of the one they came from.

When a cell divides during mitosis, some organelles split between two daughter cells. For example, mitochondria are able to grow and divide during interphase, so daughter cells each have enough mitochondria. However, the Golgi apparatus breaks down before mitosis and is reassembled in each of the new daughter cells.

Meiosis Cell Division

Meiosis is the second main way cells divide. Meiosis is cell division, producing sex cells like female egg cells or male sperm cells.

In meiosis, each new cell contains a unique set of genetic information. After meiosis, sperm and egg cells can join to form a new organism.

Meiosis is the reason we have genetic diversity in all sexually reproducing organisms. During meiosis, a small part of each chromosome breaks off and attaches to another chromosome. This process is called ” crossing over ” or ” genetic recombination “.

Genetic recombination is the reason why perfect siblings made up of egg and sperm cells from the same two parents can look so different from each other.

The Meiosis Cell Cycle

Meiosis consists of two cycles of cell division, simply referred to as meiosis-1 and meiosis-2.

Meiosis-1 halves the number of chromosomes. Meiosis-2 halves the amount of genetic information in each chromosome of each cell.

The end result is four daughter cells, called haploid cells . Haploid cells have only one set of chromosomes i.e. half the number of chromosomes as the parent cell.

Before meiosis-1 begins, the cell goes through interphase. Like mitosis, the parent cell uses this time to prepare for cell division by gathering nutrients and energy and making a copy of its DNA.

During the next stages of meiosis, this DNA is changed during genetic recombination and then splits among the four haploid cells .

Overall this was cell division, hope you understand. Other important articles related to cell are given below, must also read them. Share and Like Facebook Page

Also read – What is DNA Sequencing ?

What is Chromatin ?

Chromatin is a complex mixture of DNA and proteins that makes up chromosomes within the nucleus of eukaryotic cells. Nuclear DNA does not appear in free linear strands; It is highly condensed and wrapped around nuclear proteins to fit inside the nucleus.

What is centriole?

Centrioles are paired barrel-shaped organelles located in the cytoplasm of animal cells near the nuclear envelope. Centrioles play a role in organizing the microtubules that serve as the skeletal system of the cell. They help determine the locations of the nucleus and other organelles within the cell.

What are diploid cells ?

Diploid cells have two complete sets of chromosomes. Since daughter cells contain exact copies of their parent cell’s DNA, no genetic variation is created through mitosis in normal healthy cells. In humans, cells other than human sex cells are diploid and contain 23 pairs of chromosomes.

What are haploid cells ?

Haploid cells have only one set of chromosomes i.e. half the number of chromosomes as the parent cell. The term haploid also refers to the number of chromosomes in the egg or sperm cells, also called gametes. In humans, gametes are haploid cells containing 23 chromosomes, each containing one of the chromosome pair, which is present in diploid cells ((diploid cells)).

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