Difference Between Mitosis and Meiosis

The growth of cells happen in two ways; replication and expanding in volume. Skin and blood tissues actively divide while fat tissues expand. Cell replication happens in two ways; producing identical copies leading to two cells or making four half copies for sexual reproduction. The genetic content is made whole again through fertilization. Such two processes are mitosis and meiosis.

(Mitosis results in two identical daughter cells while meiosis results in four haploid daughter cells as seen in the image above.)

These two processes have various purpose although they have common features too. Let us take a look at their similarities.

• They occur in multiple stages and share common steps such as:
  • Replication and condensation of DNA
  • Degradation of nuclear membrane
  • Formation of spindle
  • Segregation of chromosomes
  • Nuclear reformation
• Both of them are cell division process.
• They share a common goal and that is to split the nucleus and DNA content between two daughter cells.
• The action where chromosomes are pulled apart is the same for both processes. (1, 2, 3, and 4)

The fundamental stages of meiosis and mitosis

• Interphase – The cell grows and replicate as it prepares for cellular division.
• Prophase – The process in which the nuclear membrane degrades.
• Metaphase – In this phase, the chromosomes align in the middle of the cell.
• Anaphase – In this phase, the chromosomes are pulled apart.
• Telophase – The cell splits and separate into two cells.

Now that we know the common features shared by mitosis and meiosis, the next step is to tell their difference. The primary difference between mitosis and meiosis is the end product. Mitosis always ends up to two daughter cells wherein the number of chromosomes is the same as the parent cell. On the flip side, meiosis would result in four daughter cells and they contain half of the chromosomes of the parent cells. (3, 4, 5, and 6)

The table below shows the differences between the fundamental stages of meiosis and mitosis.

Both meiosis and mitosis share common steps/phases but with a few notable differences. They are the following:

Steps/Phase	Meiosis	Mitosis
Prophase (In this phase, the chromosomes condense and the centrosomes start to form an early spindle.	Prophase I is longer than the prophase phase in mitosis. In prophase I, the homologous chromosomes get in contact with each other (chiasmata) leading to a cross over. As a result, the chromosomes exchange sections of DNA.	The prophase phase of mitosis is shorter when compared to that of meiosis. There is no possibility of crossing over of chromosomes.
Metaphase (This is the phase where the chromosomes fall in line along the plate secondary to the effect of microtubule spindle fibers, which are attached to the chromosomes by kinetochores at the chromosome’s centromere.	The pair of homologous chromosomes fall in line along the metaphase plate in metaphase I. The homologous pairs are oriented randomly respective of the cell poles. The process is called the law of independent assortment. This makes sure the random distribution of chromosomes to the daughter cells.	A single pair of chromatids/chromosomes fall in line along the metaphase plate. The resulting chromatids are the same in features. Hence, the chromosome’s orientation has no bearing. (6, 7, and 8)
Anaphase (In this phase, the chromosomes are split to the cell’s contradicting poles).	The cohesion at the centromere of chromosomes in the anaphase of meiosis I is not cleaved. It continues holding the chromatids together as the homologous chromosomes are separated to the cells’ opposite poles. (6, 7, and 8)	In mitosis’ anaphase stage, cohesion protein that holds the centromere of the sister chromatids together is cleaved. Hence, it enables the chromatids to separate to the cell’s opposing poles. They are now called chromosomes.
Telophase (A phase wherein the nuclear membrane reforms around the new chromosomes, starts to uncoil and look less condense. Also, the spindle microtubules start to disintegrate causing each of the daughter cell to inherit a centrosome. The plasma membrane of the cell pinches leaving the daughter cells with separate plasma membranes (cytokinesis). (9, 10)	Cytokinesis occurs two times – after the telophase I and after telophase II.	Cytokinesis does not always happen. (11)

The major differences between mitosis and meiosis

The process of mitosis results in two identical daughter cells while meiosis results in four distinct daughter cells that are not identical to each other and to the parent cells. Such a process results in gametes (eggs and sperms) in the life cycle of animals and spores in the life cycle of plants and fungi. (11, 12)

The table below shows the summary of the differences between mitosis and meiosis.

Point of comparison	Mitosis	Meiosis
Purpose	Unicellular organism – To proliferate Multicellular organism – to grow, repair, and regenerate damaged tissues. (2, 4)	The purpose is to create gametes to prepare for sexual reproduction and eventually produce a zygote.
Outcome	The process results in two diploid cells with the same genetic information.	The process results in four haploid cells and each of them has distinct genetic information.
Organisms that perform such processes	Both unicellular and multicellular organism (eukaryotes). Bacteria have their mitosis counterpart, which is called binary fission.	Meiosis happens in organisms that have the ability to perform sexual reproduction.
Duration/length of the process	Mammalian cells in culture – 10 hours. Budding yeast – about 80 minutes for cycles to take place. Bacteria – usually occurs every 20 minutes. (5, 6)	The length of the process varies and there are factors that can affect the duration such as: Temperature Environment Amount of nuclear DNA
Etymology/origin	Mitosis is a Greek word which means thread derived from the structure of chromosomes, which is thread-like when visualized under the microscope. (13, 14, and 15)	Meiosis is a Greek word which means lessening. It pertains to the end result of meiosis in which the genetic information is only half in the resulting daughter cells.
Who discovered?	The process of mitosis was first described by Walther Flemming in 1882 in relation to his work called cell substance, nucleus, and cell division.	The fusion of the sperm and egg in a transparent egg of sea urchin was described by Oskar Hertwig in 1876.
Conditions/diseases caused by an error in the process	An error in the process of mitosis is usually common in people with cancer. The genes might be switched off or become overly active.	An error in meiosis could lead in abnormalities in the chromosomes’ total number in germ cells (aneuploidy). It could lead to the following: Miscarriage Down’s syndrome (trisomy 21) Klinefelter syndrome (XY chromosomes have excess X chromosome) (10, 14, and 15)

Both mitosis and meiosis are processes needed to produce new cells. They share common processes but differ in many ways. Mitosis results in two genetically identical daughter cells (the same as the parent cells). The daughter cells have the expected chromosome number as a result of DNA replication and cell division. Mitosis is primarily used for asexual reproduction and growth.

On the flip side, the process of meiosis results in four daughter cells with identical character traits; different from the parent cells and the other daughter cells. The daughter cells are haploid (only half the number of the total chromosomes) as a result of DNA replication, crossing over of homologous chromosomes, and chromosome separation.

The division of cell happens two times; the parent cell divides and the cells that are produced from the first division will also undergo a cell division. The process of meiosis is important as it leads to the production of gametes; the sperm cell and the egg cell. These are used for sexual reproduction. The gametes – sperm cell and egg cell fuse together to form a zygote. What is a zygote? It is a diploid cell containing the expected chromosome number.