Introduction
Cell division is a fundamental process for life. It is useful not only to generate new cells but also to help in growth and development. This cell division can take place through 2 different modes - Mitosis and Meiosis. We are about to look at a few characteristics, the basic definitions, and the difference between mitosis and meiosis.
Cell reproduction is the process of creating new species using a single-parent cell. However, this process is different in unicellular and multicellular organisms.
Unicellular organisms perform cell reproduction or division to generate daughter cells. Multicellular organisms perform cell division to enhance growth and replace worn-out cells from the body.
To put it straight, mitosis creates new body cells, whereas meiosis generates sperm and egg cells.
Mitosis and Meiosis
Mitosis is a core process that replicates all of its content, including duplication of its chromosomes. The result is two identical daughter cells. Mitosis is a critical process to life, and hence this is controlled by several genes.
If the genes are not regulated properly, it might cause serious health issues in humans, such as cancer.
Meiosis, on the other side, will create copies that have the same number of chromosomes in humans (in all generations). Meiosis is a two-step procedure, reducing the chromosome number by half. The result of this process is the formation of egg and sperm cells, with chromosome counts from 46 to 23. This is a reason why the human embryo has 46 chromosomes from birth (conception of egg and sperm).
Chances are likely in meiosis to exhibit genetic variations from DNA shuffling.
Following is a table to quickly describe the differences in mitosis vs meiosis.
Difference Between Mitosis and Meiosis Table
Mitosis Overview
Cell duplication and distribution are the aim of Mitosis.
This is an asexual mode of reproduction.
Nuclei form in 4 stages namely prophase, metaphase, anaphase, and telophase.
2 diploid cells are formed.
Spindle fibers disconnect after sister chromatids get separated.
Meiosis Overview
Meiosis is a form of sexual reproduction.
The resulting daughter cells are reduced in their chromosome number by half.
Eukaryotic chromosomes are formed.
Similar to mitosis, S-Phase is dominant in the meiosis form of cell replication.
A cell undergoing meiosis will either become human sperm or an egg.
Similarities Between Mitosis and Meiosis
Apart from its cell division or reproductive processes, there are 3-4 similarities between meiosis and mitosis. DNA synthesis is primarily common to both. If already formed, the cardiac tissues and nervous system cells will never replicate their daughter/sister cells either through meiosis or mitosis. Both these methods of reproduction are visible under an electron microscope.
The Cell Division Cycle
A cell cycle is a sequence of events that occur in a cell as it develops and divides. A cell stays the majority of its time in what is known as interphase, which is when it grows, copies its chromosomes, and prepares for cell division. The cell division cycle has four stages:
G1 Phase: G1 refers to the time between cell division and the beginning of DNA replication. Cells develop and monitor their surroundings to determine whether or not they should initiate another round of cell division.
S Phase: S is the time when cells replicate their chromosomes and DNA is synthesized. It also repeats the centrosome, a structure that organizes microtubules. During the M phase, centrosomes help in the separation of DNA.
G2 Phase: G2 refers to the time between the completion of DNA replication and the beginning of cell division. Cells double-check that DNA replication has occurred effectively and perform any required repairs. Mitosis begins when the G2 phase ends.
Interphase is the combination of the G1, S, and G2 phases. The word inter- signifies "between," implying that interphase occurs between mitotic (M) phases.
M Phase: M is the actual cell division period, which includes prophase, metaphase, anaphase, telophase, and cytokinesis.
M Phase
The cell splits its copy DNA and cytoplasm to form two new cells during the mitosis (M) phase. During the M phase, two distinct division-related processes occur mitosis and cytokinesis. During mitosis, the cell's nuclear DNA condenses into visible chromosomes that are dragged apart by the mitotic spindle, a specialized structure formed of microtubules. Prophase (also known as early prophase and prometaphase), metaphase, anaphase, and telophase are the four phases of mitosis. During cytokinesis, the cell's cytoplasm is split in two, resulting in the production of two new cells. With some overlap, cytokinesis usually begins just as mitosis is coming to an end. Cytokinesis varies between animal and plant cells.
Significance of Cell Division
Cell division is crucial in all living creatures since it is required for growth, repair, and reproduction. Cell division is used to reproduce cells in both unicellular and multicellular organisms. The method by which unicellular creatures reproduce is known as binary fission. Cell division aids in the creation of gametes, which unite to create the organism in multicellular organisms. This procedure aids in:
Renewing of damaged cells.
Production of new cells from older ones.
Maintains the total number of chromosomes.
Increases the number of cells available for growth and development.
Repairs and controls damage caused to the cells.
Also helps in the survival and growth of living organisms.
It is responsible for an individual's form, size, and healthy growth and development.
In plants, mitosis helps in the formation of new parts and in repairing the damaged parts.
Most Important Stage of the Cell Cycle
Interphase is the most crucial step of the cell cycle. The cell stays most of the time in interphase. The cell prepares for division during this phase. During this phase, the cell undertakes cell growth and replication.
Chromosomes
These are thread-like structures that contain tightly packed DNA within the nucleus. The structural support is provided by histone proteins, which are coiled around DNA. Chromosomes help in the replication and distribution of DNA during cell division. Each chromosome includes a centromere that splits it into two sections: the p (short) arm and the q (long) arm. The centromere is found at the cell's constriction point, which may or may not be the chromosome's core.
In humans, 46 chromosomes are organized into 23 pairs, including 22 pairs of autosomes. For reference, autosomes 1-22 are labeled. Each chromosome pair is made up of one chromosome inherited from the mother and one chromosome inherited from the father.
Conclusion
Both mitosis and meiosis have their roles in human development and genetic message transmission. Credits to ‘Walther Flemming’ for the discovery of mitosis and helping new cells grow and nurture. Also, thanks to the brain of ‘Oscar Hertwig for uncovering meiosis and making continuity of required cells possible with definite DNA variants.
FAQs on Mitosis and Meiosis
1. What is Mitosis and Meiosis?
Mitosis and meiosis are cell division processes that occur either sexually or asexually to create new cells and help in the growth of existing cells.
2. Give 1 Significant Factor for Mitosis and Meiosis Difference.
The core of mitosis is to repair non-existent cells and meiosis is focussed to create new daughter cells with half the count of parent chromosomes.
3. What are the 5 Stages under Prophase 1?
Prophase 1 is divided into 5 stages namely Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis.
4. Is There any Genetic Difference in the Results of Mitosis vs Meiosis?
Yes. Much genetic variation is not changed in Mitosis. But in the case of meiosis, genetic variation is increased.
5. State an Example of Genetic Errors that Occur from Meiosis and Mitosis.
An error in the process of meiosis might lead to Down Syndrome (trisomy 21). Disturbances during mitosis may lead to cancer mutations and aneuploidy.
6. Can I get relevant study material for the Biology topic “Mitosis and Meiosis”?
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