Another difference between mitosis and meiosis is that:
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Most important difference is that Mitosis results in 2 daughter cells with same number of chromosomes( Takes place in somatic cells) whereas Meiosis is a reduction division where the chromosome number is halved in the daughter cells (takes place in reproductive cells).
Mitosis is a process of asexual reproduction in which the cell divides in two producing a replica, with an equal number of chromosomes in each resulting diploid cell.
Meiosis is a type of cellular reproduction in which the number of chromosomes are reduced by half through the separation of homologous chromosomes, producing two haploid cells.
Following are the differences between Mitosis and Meiosis:
S.N.
Differences
Mitosis
Meiosis
1
Type of Reproduction
Asexual
Sexual
2
Genetically
Similar
Different
3
Crossing Over
No, crossing over cannot occur.
Yes, mixing of chromosomes can occur.
4
Number of Divisions
One
Two
5
Pairing of Homologs
No
Yes
6
Mother Cells
Can be either haploid or diploid
Always diploid
7
Number of Daughter Cells produced
2 diploid cells
4 haploid cells
8
Chromosome Number
Remains the same.
Reduced by half.
9
Chromosomes Pairing
Does Not Occur
Takes place during zygotene of prophase I and continue upto metaphase I.
10
Creates
Makes everything other than sex cells.
Sex cells only: female egg cells or male sperm cells.
11
Takes Place in
Somatic Cells
Germ Cells
12
Chiasmata
Absent
Observed during prophase I and metaphase I.
13
Spindle Fibres
Disappear completely in telophase.
Do not disappear completely in telophase I.
14
Nucleoli
Reappear at telophase
Do not reappear at telophase I.
15
Steps
Prophase, Metaphase, Anaphase, Telophase.
(Meiosis 1) Prophase I, Metaphase I, Anaphase I, Telophase I; (Meiosis 2) Prophase II, Metaphase II, Anaphase II and Telophase II.
16
Karyokinesis
Occurs in Interphase.
Occurs in Interphase I.
17
Cytokinesis
Occurs in Telophase.
Occurs in Telophase I and in Telophase II.
18
Centromeres Split
The centromeres split during anaphase.
The centromeres do not separate during anaphase I, but during anaphase II.
19
Prophase
Simple
Complicated
20
Prophase
Duration of prophase is short, usually of few hours.
Prophase is comparatively longer and may take days.
21
Synapsis
No Synapsis
Synapsis of Homologous chromosomes takes place during prophase.
22
Exchange of Segments
Two chromatids of a chromosome do not exchange segments during prophase.
Chromatids of two homologous chromosome exchange segments during crossing over.
23
Discovered by
Walther Flemming
Oscar Hertwig
24
Function
Cellular reproduction and general growth and repair of the body.
Genetic diversity through sexual reproduction.
25
Function
Takes part in healing and repair.
Takes part in the formation of gametes and maintenance of chromosome number.
Cells of living organisms divide and reproduce genetically in a process called the cell cycle. This cell cycle is made up of four major phases: G1, S, G2, and M phase.
During G1, the cell evaluates the initiation of cell division. S phase is when the cell synthesizes the DNA and replicates its chromosomes. G2 is the phase where the cell checks whether the replication was done correctly and, if not, initiates necessary repairs. Lastly, the M phase is the actual cell division.
In eukaryotes, two types of cell divisions exist: mitosis and meiosis. While these processes are similar in terms of principles, they also have distinct characteristics. Below, we’ve tabulated the 16 major differences between mitosis and meiosis.
Type of cell division and occurs in what type of cells
Asexual division; Mitosis occurs in somatic cells.
Somatic cells (or vegetative cells) are cells that make up the bodies of living organisms, other than the sex cells.
Somatic cells include muscle cells, bone cells, skin cells, nerve cells, etc. (collectively known as body cells)
Sexual division; Meiosis occurs in sex cells or gametes.
In animals like humans, meiosis takes place in male sperm cells and female egg cells in order to prepare them for sexual reproduction.
In plants, sex cells are located in the pollen in the stamen and egg cells in the pistil.
Duration
Mitosis involves only one cell division that is composed of four major phases: prophase, metaphase, anaphase, and telophase.
Meiosis is quite longer as it involves two successive divisions that results to the reduction in chromosome number.
Basically, it is divided into two: meiosis I and meiosis II. Meiosis I and II have the same phases like mitosis, only different in some events.
Number of chromosomes
Only one division results to diploid (2n) offspring
Two divisions results to haploid (n) offspring
Number of daughter cells produced
Two. The resulting daughter cells are genetically the same because no recombination occurred during the process.
Four. The chromosome number of the resulting daughter cells is reduced by half (becomes haploid, n).
It is only during reproduction process that such diploid state is restored in the offspring.
Interphase
Before undergoing through the four phases, the cell first needs to grow and replicate its chromosomes in a preliminary stage called interphase.
A sex cell will only undergo interphase once. No interphase will happen before meiosis II.
Prophase
After interphase, the cell proceeds to prophase where the nuclear membrane disintegrates and the chromatin condenses to form the chromosomes.
The mitotic cell undergoes prophase only once.
Prophase in meiosis is relatively longer than that of mitosis. Prophase I in particular is composed of five stages: leptotene, zygotene, pachytene, diplotene, and diakinesis.
During prophase I, homologous chromosomes form a tetrad that is composed of four chromatids. The homologous chromosomes that make up tetrads are not genetically identical because they came from two different parents.
Prophase II will begin without having to undergo interphase. Again, the nuclear membrane disintegrates and the chromatin condenses.
Bouquet Stage
None
Bouquet stage is the event wherein animal and plant chromosomes converge toward one side of the cell. This occurs during prophase I.
Crossing over
None
Occurs during Pachytene of meiosis I. During crossing over, the chromosomes of each pair are exchange among each other.
Metaphase
During metaphase, the chromosomes align at the equatorial plate of the cell. This event is due to the presence of kinetochore microtubules that pull these chromosomes back and forth.
Metaphase I and II of meiosis are quite similar to mitotic metaphase. During metaphase I, homologous chromosomes begin to align themselves at the equatorial plate as they bind to the mitotic spindle.
During metaphase II, single chromosomes align at the equatorial plate after each cell is done forming the spindle fibers.
Anaphase
During this stage, each (single stranded) chromosome pair is segregated toward the opposite poles of the cell. This activity is initiated by the mitotic spindle.
During anaphase I, (double stranded) chromosomes are separated toward each cellular pole.
On the other hand, (single stranded) chromosomes are the ones being segregated during anaphase II.
Telophase
Telophase is where the the complete transfer of genetic material from the parent cell to the daughter cells occurs. During this stage, the nuclear membrane is reformed.
Cytokinesis, the division of the cytoplasm, occurs simultaneously with telophase.
At the end of telophase I, each resulting daughter cell bears a haploid set of chromosomes. Telophase II is quite similar to the telophase in mitosis. In the same manner, the genetic material from the parent cell is transferred to the daughter cells.
Spindle Fibers
Spindle fibers are gone in telophase.
Spindle fibers are still present after telophase I.
Genetic Variation and Recombination
None. Daughter cells are exact copies of one another.
Meiosis contributes to genetic variation since recombination and crossing over occur as a result of the random separation of homologous chromosomes and the transfer of genes among them.
Function
(a) Occurring in somatic cells, the main goal of mitosis is to facilitate growth, repair, and replacement. Since mitosis involves the division of somatic cells, it is really needed to produce more cells, especially during the early stages of development.
(b) Aside from growth, it is also important to regenerate damaged and lost cells. For instance, damaged tissues can be repaired by mitosis by producing new ones (i.e., scar tissues). Interestingly, some organisms utilize mitosis to replace entire body parts.
(c) Mitosis also occurs in prokaryotes as an essential form of asexual reproduction. Prokaryotes like bacteria reproduce through binary fission, wherein they simply make duplicate copies of themselves. As a result, genetic variation is scarce.
(a) Meiosis occurs only in the sex cells of living organisms as a means to maintain the chromosome number of the offspring. Since fertilization involves the fusion of cells to produce a new cell, the number of alleles in their gametes should be regulated in order to avoid genetic defects.
(b) Another function of meiosis is the maintenance of genetic diversity on which the process of natural selection acts upon. Without it, the perpetuation of species would not be possible.
– “Pearson – The Biology Place”. Accessed October 06, 2017. Link.
– “metaphase | Learn Science at Scitable”. Accessed October 06, 2017. Link.
– “Pearson – The Biology Place”. Accessed October 06, 2017. Link.
– “anaphase | Learn Science at Scitable”. Accessed October 06, 2017. Link.
– “telophase | Learn Science at Scitable”. Accessed October 06, 2017. Link.
