Mitosis vs Meiosis


Mitosis vs Meiosis
Mitosis and meiosis serve different functions and produce different types of daughter cells.

Mitosis and meiosis are the two mechanisms of cell division in eukaryotes. These cellular events ensure growth, development, and genetic diversity in organisms. However, they are fundamentally different in their functions and outcomes.

  • In mitosis, a diploid (2n) cell yields two diploid daughter cells. The function is for growth and repair.
  • In meiosis, a diploid (2n) cells yields two haploid (n) daughter cells. The function is for making sex cells.

What are Mitosis and Meiosis?

Mitosis

Mitosis is the process of cell division that produces two genetically identical daughter cells from a single parent cell. This form of cell division functions in growth, tissue repair, and asexual reproduction in some organisms. Mitosis is part of the cell cycle.

Meiosis

Meiosis, on the other hand, produces gametes (sperm and egg cells in animals, and spores in plants and fungi). It results in four non-identical daughter cells, each with half the number of chromosomes of the parent cell. This process is crucial for sexual reproduction and genetic diversity.

Steps of Mitosis and Meiosis

The names of the steps in mitosis and meiosis are the same. However, they don’t work exactly the same way. Specifically, crossing over occurs in meiosis I, so the chromosomes that separate into daughter cells are not identical to parent cells. Also, the division of chromosome in metaphase differs. In mitosis metaphase and anaphase II in meiosis, sister chromatids separate. In anaphase I of meiosis, homologous chromosomes (not chromatids) separate.

Mitosis

  1. Interphase: DNA replication occurs, preparing the cell for division.
  2. Prophase: Chromosomes condense, and the nuclear envelope dissolves.
  3. Metaphase: Chromosomes align at the equatorial plane.
  4. Anaphase: Sister chromatids separate and move to opposite poles.
  5. Telophase: New nuclear envelopes form around each set of chromosomes.
  6. Cytokinesis: Cytoplasm divides, creating two identical daughter cells.

Meiosis

There are two rounds of cell division in meiosis: Meiosis I and Meiosis II.

Meiosis I
  1. Interphase: Similar to mitosis, DNA replication occurs.
  2. Prophase I: Chromosomes pair up in homologous pairs, and crossing-over occurs.
  3. Metaphase I: Homologous pairs align at the equatorial plane.
  4. Anaphase I: Homologous chromosomes separate to opposite poles.
  5. Telophase I: Nuclear membranes reform, followed by cytokinesis.
Meiosis II
  1. Prophase II: Chromosomes condense; nuclear envelope dissolves.
  2. Metaphase II: Chromosomes align at the equatorial plane.
  3. Anaphase II: Sister chromatids separate.
  4. Telophase II: Nuclear membranes reform, followed by cytokinesis, resulting in four non-identical daughter cells.

Similarities

  • Both mitosis and meiosis begin with a single parent cell.
  • Both processes have an interphase stage where DNA replication occurs.
  • Fundamental stages such as prophase, metaphase, anaphase, and telophase are present in both.

Mitosis vs Meiosis Differences

Mitosis and meiosis have different numbers of cell division cycles, events in the stages of division, outcomes, and functions in organisms.

Mitosis vs Meiosis Venn Diagram
While both mitosis and meiosis are forms of cell division, they have different outcomes.

Interphase

Both mitosis and meiosis start out with DNA replication, but with different ultimate goals.

  • Mitosis: DNA replication produces identical sister chromatids.
  • Meiosis: DNA replication also occurs, but crossing-over in Prophase I will create genetic diversity.

Prophase

  • Mitosis: Chromosomes condense, but there’s no formation of homologous pairs or crossing-over.
  • Meiosis: Prophase I includes crossing-over, creating genetic diversity.

Metaphase

  • Mitosis: Individual chromosomes align at the metaphase plate.
  • Meiosis: In Metaphase I, homologous pairs align, not individual chromosomes.

Anaphase

  • Mitosis: Sister chromatids separate, ensuring each daughter cell gets identical sets of chromosomes.
  • Meiosis: In Anaphase I, homologous chromosomes separate. In Anaphase II, sister chromatids separate, similar to mitosis, but the chromatids may not be identical due to crossing-over.

Number of Steps

Mitosis has one round of cell division, while meiosis has two rounds. In both cases, the steps involve prophase, metaphase, anaphase, telophase, and cytokinesis.

  • Mitosis: One round of cell division.
  • Meiosis: Two rounds of cell division.

Outcome

While mitosis yields two daughter cells that are genetically identical (2n) to the parent cell, meiosis produces four haploid (n) cells that are genetically different from the parent cell.

  • Mitosis: Two identical daughter cells.
  • Meiosis: Four non-identical daughter cells with half the chromosome number.

Mitosis vs Meiosis Summary Table

This table summarizes the key differences between mitosis and meiosis.

CriteriaMitosisMeiosis
FunctionGrowth, repairReproduction
No. of DivisionsOneTwo
Daughter CellsTwo, identicalFour, non-identical
Chromosome NumberSame as parentHalf of parent
InterphaseDNA replicationDNA replication
ProphaseNo crossing-overCrossing-over occurs
MetaphaseChromosomes alignHomologous pairs align
AnaphaseSister chromatidsHomologues, then chromatids

References

  • Maton, A.; Hopkins, J.J.; et al. (1997). Cells: Building Blocks of Life. New Jersey: Prentice Hall. ISBN 978-0-13-423476-2.
  • Hassold, T.; Hunt, P. (2001). “To err (meiotically) is human: the genesis of human aneuploidy”. Nature Reviews Genetics. 2 (4): 280–91. doi:10.1038/35066065
  • Hunter, N. (2015). “Meiotic Recombination: The Essence of Heredity”. Cold Spring Harbor Perspectives in Biology. 7 (12): a016618. doi:10.1101/cshperspect.a016618
  • Snustad, D.P.; Simmons, M.J. (2008). Principles of Genetics (5th ed.). Wiley. ISBN 978-0-470-38825