Diploid: Definition, Reproduction of Cells, Types and Life Cycles

It is a cell that contains two sets of chromosomes, which is double the number of haploid chromosomes.

Each pair of chromosomes in a diploid cell is considered a set of homologous chromosomes.

A single set of chromosomes consists of two chromosomes, one of which is donated by the mother and the other by the father. Humans have 23 sets of homologous chromosomes. Paired sex chromosomes are the homologues (X and Y) in men and the homologues (X and X) in women.

The somatic cells in your body are diploid cells. Somatic cells include all types of cells in the body, except gametes or sex cells .

Gametes are haploid cells. During sexual reproduction, gametes (sperm and ovules) fuse in fertilization to form a diploid zygote. The zygote develops in a diploid organism.

Sex cells or gametes contain haploid cells, which means that these cells have a set of chromosomes, that is, 23 chromosomes. There are only 23 chromosomes in the human egg and 23 chromosomes in the human sperm.

These cells are formed after traversing a special cell division called meiosis. Therefore, the progeny inherit a set of chromosomes from the mother and a set from the father. After fertilization, they form a diploid zygote. This diploid zygote develops into a diploid species.

The diploid cells have two homologous copies of each chromosome inherited from the mother and the father. All mammals are organisms of this type, with the exception of some species.

There are 46 chromosomes in human diploid cells and human haploid cells have 23 chromosomes. The diploid cells are indicated by 2n = 2x and the haploid cells are indicated by n, where n = number of chromosomes and x = number of monoploids.

Diploid number

The diploid number of a cell is the number of chromosomes in the nucleus of the cell. This number is commonly abbreviated as 2n, where n represents the number of chromosomes. For humans, this equation would be 2n = 46. Humans have 2 sets of 23 chromosomes for a total of 46 chromosomes:

  • Autosomal chromosomes (non-sexual chromosomes): 22 series of 2.
  • Sex chromosomes: 1 set of 2.

Reproduction of diploid cells

The diploid cells reproduce by the process of mitosis. In mitosis, a cell makes an identical copy of itself allowing its DNA to replicate and distribute equally between two daughter cells.

Somatic cells pass through the mitotic cell cycle, while gametes reproduce by meiosis. In the meiotic cell cycle, four daughter cells are produced instead of two. These cells are haploid and contain half the number of chromosomes that the original cell.

Types

Células poliploides y aneuploides:

The term ploidy refers to the number of sets of chromosomes that are found in the nucleus of a cell. The sets of chromosomes in the diploid cells are presented in pairs, while the haploid cells contain half the number of chromosomes that a diploid cell.

A cell that is polyploid has additional sets of homologous chromosomes. The genome in this type of cells contains three or more haploid sets. For example, a cell that is triploid has three sets of haploid chromosomes and a cell that is tetraploid has four sets of haploid chromosomes.

A cell that is aneuploid contains an abnormal amount of chromosomes. It may have extra or missing chromosomes or it may have a chromosome number that is not a multiple of the haploid number.

Aneuploidy occurs as a result of a chromosomal mutation that occurs during cell division. The homologous chromosomes do not separate correctly, which results in daughter cells with too many or too few chromosomes.

Diploid and haploid life cycles

Most plant and animal tissues consist of diploid cells. In multicellular animals, organisms are typically diploid throughout their life cycle.

Plant multicellular organisms, such as flowering plants, have life cycles that vacillate between the periods of a diploid stage and a haploid stage. Known as alternating generations, this type of life cycle is exhibited in both non-vascular and vascular plants.

In liverworts and mosses, the haploid phase is the main phase of the life cycle. In plants with flowers and conifers, the diploid phase is the primary phase and the haploid phase is totally dependent on the diploid generation for survival.

Other organisms, such as fungi and algae, spend most of their life cycles as haploid organisms that reproduce by spores.