Why Do Cells Use Mitosis or Meiosis? Understanding Each Process
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 Overview
Cell duplication and distribution is 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.
Differences Between Mitosis and Meiosis in Detail
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 in Tabulated Form
MITOSIS | MEIOSIS |
During the Interphase stage, genetically identical sister chromosomes formed, due to the replication of each chromosome. | At Interphase, the DNA will be duplicated but the chromosome is not visible. |
Homologous sister chromosomes appear in pairs at Prophase 1. Chiasmata is the term used to refer to the crossing-over of non-sister chromatids. | At Prophase, Mitotic spindle forms after the development of 2 identical sister chromatids. |
Chromosomes get arranged and adjusted with the Metaphase plate. | Chromosomes get organized at the Metaphase plate’s equator. |
At Anaphase, homologous pairs move away as reverse poles. | Contraction of sister fibers being at Anaphase and sets of daughter cells are observed at each pole. |
4 daughter cells with half the count of parent chromosomes. | 2 daughter cells with the same count of parent chromosomes. |
In case of time constraints, students can refer to this table directly. This table will also come in handy while revising the topic. You may get information about many such topics of Biology on Vedantu's website for free.
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.
Fun Facts about Mitosis
Some very interesting facts about Mitosis are given below to make the learning process interesting for you:
Mistakes made during mitotic cell division can result in changes in the DNA
Two genetically identical daughter cells are generated as a result of mitosis
Mitotic cell division takes place in four phases namely
Prophase
Metaphase
Anaphase
Telophase
The structure responsible for moving the chromosomes during the process of mitosis is known as the spindle
Fun facts about Meiosis
Some facts about meiosis that you may find interesting are given below:
Meiotic cell division takes place during reproduction only
Chromosome numbers are halved during meiotic cell division
Every individual is unique due to genetic variation that takes place during meiosis
In meiosis, diploid cells are converted to haploid and again converted back to being diploid.
Even a minor error during the meiotic cell division can result in a permanent impact on human development
A mutation is possible during meiotic cell division
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 vs Meiosis: Main Differences for Students
1. What are mitosis and meiosis in simple terms?
In simple terms, mitosis is a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth. Meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information. These cells are our sex cells – sperm in males, eggs in females.
2. What are the key differences between mitosis and meiosis?
The key differences between mitosis and meiosis are based on their purpose, process, and outcome:
Purpose: Mitosis is for growth, repair, and asexual reproduction. Meiosis is exclusively for producing gametes for sexual reproduction.
Number of Divisions: Mitosis involves one cycle of cell division. Meiosis involves two consecutive cycles (Meiosis I and Meiosis II).
Daughter Cells: Mitosis produces two genetically identical daughter cells. Meiosis produces four genetically unique daughter cells.
Chromosome Number: Mitosis maintains the chromosome number; daughter cells are diploid (2n). Meiosis halves the chromosome number; daughter cells are haploid (n).
Genetic Variation: Mitosis produces no genetic variation. Meiosis introduces genetic variation through processes like crossing over.
3. How does the chromosome number change in mitosis compared to meiosis?
In mitosis, a parent cell that is diploid (2n) produces two daughter cells that are also diploid (2n). The chromosome number remains the same, which is why it's called equational division. In meiosis, a diploid (2n) parent cell undergoes two divisions to produce four haploid (n) daughter cells. The chromosome number is halved, which is why Meiosis I is known as reductional division.
4. What are the five substages of Prophase I in meiosis?
Prophase I of meiosis is a complex phase and is broken down into five distinct substages. These are:
Leptotene: Chromosomes start to condense and become visible.
Zygotene: Homologous chromosomes begin to pair up in a process called synapsis.
Pachytene: Crossing over occurs, where genetic material is exchanged between homologous chromosomes.
Diplotene: The paired chromosomes begin to separate but remain attached at points called chiasmata.
Diakinesis: The chromosomes fully condense, and the nuclear envelope breaks down, preparing for Metaphase I.
5. What is the final outcome of mitosis and meiosis in terms of the cells produced?
The final outcome of mitosis is the production of two genetically identical somatic cells, each with a full set of chromosomes (diploid, 2n). The outcome of meiosis is the production of four genetically distinct gametes (sex cells like sperm or eggs), each with half the number of chromosomes of the parent cell (haploid, n).
6. Why is meiosis called 'reductional division' while mitosis is 'equational division'?
These terms describe the effect on the chromosome number. Mitosis is called equational division because the number of chromosomes in the daughter cells is equal to that of the parent cell (e.g., 46 to 46 in humans). Meiosis is called reductional division because the first of its two divisions (Meiosis I) reduces the chromosome number by half (e.g., from 46 to 23 in humans). This reduction is essential for producing haploid gametes.
7. What are the important similarities between mitosis and meiosis?
Despite their differences, mitosis and meiosis share several fundamental similarities. Both processes:
Begin with a diploid parent cell.
Involve DNA replication during the preceding Interphase.
Follow the same basic sequence of phases: Prophase, Metaphase, Anaphase, and Telophase (though meiosis goes through them twice).
Utilise a spindle apparatus to separate chromosomes.
8. What would be the consequence if crossing over did not occur during meiosis?
If crossing over failed to occur during Prophase I of meiosis, it would severely limit genetic variation. The homologous chromosomes would not exchange genetic segments. Consequently, the gametes produced would contain chromosomes that are purely maternal or paternal in origin, drastically reducing the genetic diversity of offspring. This genetic recombination is a key driver of evolution and adaptation.
9. Where in the human body do mitosis and meiosis occur, and why is this difference in location important?
Mitosis occurs in almost all somatic (body) cells throughout the body, such as skin, muscle, and bone cells. It is essential for growth, replacing old or damaged cells, and tissue repair. In contrast, meiosis occurs only in the germline cells within the gonads (testes in males and ovaries in females). This strict localisation is critical because it ensures that only gametes (sperm and eggs) receive a reduced set of chromosomes, a prerequisite for sexual reproduction to restore the diploid number upon fertilisation.
10. What is the overall biological significance of having two different types of cell division?
The existence of two distinct division types serves two separate, vital functions for an organism. The significance of mitosis is ensuring genetic continuity and stability for the growth and maintenance of an individual organism. Every somatic cell gets an identical, complete copy of the genome. The significance of meiosis is creating genetic diversity for the species through sexual reproduction. By producing unique haploid gametes, meiosis ensures that offspring are genetically different from their parents and each other, which is crucial for adaptation and long-term species survival.
