Haploid Cell

MEIOSIS 2, FOUR DAUGHTER CELLS (TETRADS), 2nd Division, Lilium (Lily), 400X at 35mm. The four resulting cells are haploid (have 1/2 the chromosome number of the original mother cell).
These are four daughter cells produced by meiosis in a plant cell. The four resulting cells are haploid (have 1/2 the chromosome number of the original mother cell). Ed Reschke/ Photolibrary/ Getty Images

A haploid cell is a cell that contains one complete set of chromosomes. Gametes are haploid cells that are produced by meiosis.

Haploid Number

The haploid number is the number of chromosomes within the nucleus of a cell that constitutes one complete chromosomal set. This number is commonly abbreviated as n, where n stands for the number of chromosomes. The haploid number will be different for different organisms.

In humans, the haploid number is expressed as n=23.

Haploid human cells have 1 set of 23 chromosomes:

  • Autosomal chromosomes (non-sex chromosomes): 22 sets.
  • Sex chromosomes: 1 set.

Diploid human cells have 2 sets of 23 chromosomes for a total of 46 chromosomes:

  • Autosomal chromosomes: 22 sets of 2.
  • Sex chromosomes: 1 set of 2.

Haploid Cell Reproduction

Haploid cells are produced by the process of meiosis. In meiosis, a diploid cell divides twice to produce four haploid daughter cells. Prior to the start of the meiotic cell cycle, the cell replicates it DNA and increases its mass and organelle numbers in a stage known as interphase. As a cell progresses through meiosis, it goes through the stages of prophase, metaphase, anaphase and telophase twice. At the end of meiosis I, the cell divides into two cells. Homologous chromosomes separate, however sister chromatids remain together. The cells then enter meiosis II and divide again.

At the end of meiosis II, sister chromatids separate leaving each of the four cells with half the number of chromosomes as the original cell. In the process of sexual reproduction, haploid sex cells unite at fertilization and become a diploid cell.

Spores

In organisms such as plants, algae, and fungi, asexual reproduction is accomplished through the production of haploid spores.

These organisms have life cycles that can alternate between a haploid phase and a diploid phase. This type of life cycle is known as alternation of generations. In plants and algae, haploid spores develop into gametophyte structures without fertilization. The gametophyte produces gametes and is considered the haploid phase in the life cycle. The diploid phase of the cycle consists of the formation of sporophytes. Sporophytes are diploid structures that develop from the fertilization of gametes.

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Bailey, Regina. "Haploid Cell." ThoughtCo, Feb. 8, 2017, thoughtco.com/haploid-cell-373467. Bailey, Regina. (2017, February 8). Haploid Cell. Retrieved from https://www.thoughtco.com/haploid-cell-373467 Bailey, Regina. "Haploid Cell." ThoughtCo. https://www.thoughtco.com/haploid-cell-373467 (accessed November 24, 2017).