Karyokinesis : Defination, Stages and Importance

Karyokinesis: Definition, Stages, and Importance

What is Karyokinesis

The term karyokinesis Means etymologically consists of two words from the Greek language: káryon, which is translated as the nucleus, and kínēsis, which refers to movement or division. Therefore, in a biological context, karyokinesis refers to the process by which the nucleus of a cell divides.

Also known as mitosis, karyokinesis, astral mitosis, or amphibian mitosis. This is the first stage of mitosis, which involves the precise distribution of genetic material from one stem cell to the two daughter cells.

In biology, the word cell division is often used to describe the longitudinal division of chromosomes and the division of the nucleus and cytoplasm, resulting in two new cells with the same number of chromosomes and the same genetic information as stem cells. Two processes occur in cell division: nuclear division or karyokinesis, and cytoplasmic division or cytokinesis.

These two transformations can take place, one after the other, or independently, the first and the other after a while. However, for the nuclear division to take place, deoxyribonucleic acid (DNA) replication must first have taken place.


Karyokinesis : Stages, Importance


Stages of Karyokinesis

Karyokinesis is continuous, uninterrupted, and relatively fast, and its main function is to distribute chromosomes evenly among daughter cells. It occurs in four phases: prophase, metaphase, anaphase, and telophase.

In the initial prophase, the cell begins to break down some structures and elevate others, setting the stage for chromosome division. The chromosomes undertake their condensation, which facilitates subsequent separation. At this point, the formation of the mitosis begins. It is a structure made up of microtubes and strong fibers that are part of the cells. Organizes chromosomes and moves them during mitosis. The nucleolus, part of the nucleus where ribosomes form, disappears. An indication that the nucleus is preparing to divide. In late prophase or prometaphase, the nuclear envelope breaks down and chromosomes condense and are released.

At this stage, the chromosomes on the metaphase plate align under the rigidity of the mitotic spindle. The two sister chromatids on each chromosome are trapped by the microtubules at the opposite poles of the spindle, while all the chromosomes are aligned, ready to divide. Before anaphase continues, the cell will ensure that all chromosomes are on the metaphase plate, with their kinetochore properly attached to the microtubules. If a chromosome is not organized, the division will stop until the problem is resolved.

Anaphase: In Anaphase the sister chromatids separate and are attracted to the opposite poles of the cell. The microtubules separated from the chromosomes lengthen and push the Central poles in opposite ways.

Telophase: In this stage, The spindle disappears, the nuclear membrane forms again around each group of chromosomes, and a nucleus is repeated in each new nucleus. Chromosomes also begin to condense. In telophase, the cell is almost complete and begins to regain its normal structure while cytokinesis, the segmentation of the cell compound, occurs.

Read: Cell Structure and functions


Importance of karyokinesis

Karyokinesis is a process of significant importance for living beings, because it guarantees every cell of the organism, except the sex cells, sperm, or oocyte, can regenerate themselves, ensuring the proper functioning of both cells and tissues, which can develop, grow and regenerate within a few hours.

It means that karyokinesis allows the growth and development of the multicellular organism, body growth, and the regeneration of tissues exposed to cell destruction. That is why this complex process allows cells to survive over time, transmitting their characteristics from one generation to another. Day by day the dying cells are replaced.

Karyokinesis, about organic life, comprises the division of cells through the transformation of their nucleus, which examines the division by budding, that is, the stem cell develops a protuberance or gem that will originate another cell. Sporulation also gives rise. It is here when the stem cell breaks its nucleus many times and the nucleoli are wrapped in cytoplasm creating spores that are thrown outside. Each will form a new cell. These two techniques are exhibited by single-celled organisms such as yeasts or lower vegetables, such as hydras.

The bipartition breakdown of cells usually occurs in higher beings, such as man, which includes the so-called amitosis; the arbitrary division of the nucleus, and the cytoplasm.

Animal cells consist of an organelle devoid of a membrane called the aster or call center, which is made up of a pair of centrioles, which, when fractionated in early prophase, are located at opposite poles of the cell, creating the mitotic spindle apparatus, macrosomic or achromatic.

Frequently Asked Questions On Karyokinesis

What Happens During Karyokinesis?
Answer: Karyokinesis is the division of the nucleus that occurs in four phases. These are prophase, metaphase, anaphase, and telophase. During prophase, the chromatin condenses to form chromosomes. During metaphase, the chromosomes arrange on the equatorial plane and the formation of Central fibers takes place.

What is Karyokinesis in Biology?
Answer Definition of Karyokinesis in Biology
Karyokinesis is the division of a cell’s nucleus into daughter cells.

Is Karyokinesis the Same as Mitosis?
Answer: Karyokinesis (mitosis) Karyokinesis, also known as mitosis, is divided into a series of phases (prophase, prometaphase, metaphase, anaphase, and telophase) that lead to the division of the cell nucleus.

In which phase of mitosis does Karyokinesis occur?
Answer: DNA replication takes place during the S phase; chromosome secretion (karyokinesis) occurs during the M phase, and is followed by cell division (cytokinesis); G1 and G2 are gaps or growth phases.

What comes first Karyokinesis or cytokinesis?
Answer: Karyokinesis is defined as the division of the nucleus during the M phase of the cell cycle. This is the first step in the M phase. Cytokinesis, on the other hand, is defined as the division of the cytoplasm during the M phase of the cell cycle. This is the second step in the M phase.

What is the shortest phase of Karyokinesis?
Answer: Prophase
Prophase is the shortest phase where condensation of the chromosomes takes place.

Who Discovered Karyokinesis?
Answer: Dr. Schleicher, one of the pupils of Van Bambeke in Ghent, invented the name ‘Karyokinesis’ in 1878 (179) —i.e. nuclear motion, for the range of phenomena in question; while Mayzel (133, 134), of Warsaw, and especially Strasburger (190-1994).

Where does mitosis occur in the body?
Answer: Mitosis occurs in every part of the body, except in germ cells that are produced from meiotic cell division.

What is the longest phase of Karyokinesis?
Answer: The synthesis of DNA in interphase takes the longest due to the complexity of the genetic material being duplicated. During the interphase, nuclear DNA remains in a semi-condensed chromatin configuration.

What are the five stages of cell division?
Answer: The five phases of mitosis are interphase, prophase, metaphase, anaphase, and telophase.

What will happen if a cell completes Karyokinesis but not cytokinesis?
Answer: Cytokinesis is usually the last phase in mitosis in which the contents of the cell (cytoplasm and nuclei) are divided over two separate, identical daughter cells. The result of mitosis without cytokinesis is a cell with more than one nucleus.

What is the difference between cell cycle and cell division?
Answer: Cell division is only one of the different phases that a cell goes through during its lifetime. The cell cycle is a recurring sequence of events that includes growth, DNA synthesis, and cell division.

What phase is Karyokinesis?
Answer: Karyokinesis is the division of the nucleus that occurs in four phases. These are prophase, metaphase, anaphase, and telophase. During prophase, the chromatin condenses to form chromosomes. centrioles develop into asters and move to opposite poles.

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