Dictionary > Polypoid

Polypoid

Definition
noun
(genetics) A cell or an organism containing more than two sets of homologous chromosomes
adjective
(genetics) Of or pertaining to a condition in which there is only half of the complete set of chromosomes in somatic cells
(anatomy) Resembling a polyp, or polyp-shaped, as in polypoid lesions in stomach
Supplement
In genetics, ploidy refers to the number of sets of homologous chromosomes in the genome of a cell or an organism. Each set is designated by n. Polyploidy is the state of having more than two sets of chromosomes. The term polyploid would therefore refer to a cell (or an organism) with more than two sets of homologous chromosomes. This is used in contrast to cells or organisms with typically diploid number of homologous chromosomes. In humans and other living things, the diploid state of somatic cells is due to the resulting union of gametes in haploid state during fertilization. One of the two sets is derived from the mother’s gamete and the other is from the father’s gamete. This would result in a diploid zygote with two copies of chromosomes and is represented by 2n. Humans, in particular, have 23 chromosomes in sex cells and 46 chromosomes in somatic cells. Polyploidy occurs when there are multiple sets of chromosomes beyond the basic set. There are different types of polyploids according to the number of sets of chromosomes in a nucleus: triploid (three sets), tetraploid (four sets), pentaploid (five sets), hexaploid (six sets), heptaploid or septaploid (seven sets), octaploid or octoploid, (eight sets), decaploid (ten sets), dodecaploid (twelve sets), etc. Polyploidy is more common in plant species than animal species.
In anatomy, the term polyploid is used as a descriptive term for structures resembling polyps, as in in polypoid lesions in stomach. Nevertheless, the use of the term polploid is more popular in the field of genetics than in anatomy.
Word origin: Greek haplous (single”)
Compare:

See also:

  • chromosomes
  • ploidy
  • fertilization
  • somatic cell
  • gamete
  • Related forms:


    You will also like...

    Ecological Research Measuring & Analysis
    Ecological Research: Measuring & Analysis

    This lesson is about the methods used for ecological research, such as quadrat and transect sampling, canopy fogging, an..

    Fossil trilobite imprint in the sediment
    Insects

    There are more species of insects than any other species combined. This surely illustrates that insects have the selecti..

    mRNA
    Protein Synthesis

    Part of the genetic information is devoted to the synthesis of proteins. mRNA, a type of RNA, is produced as a transcri..

    Human Neurology
    Human Neurology

    Human Neurology deals essentially with the nervous system of humans. It also features the various theories put forward b..

    Pink Lotus plant on a pond
    Freshwater Lentic Communities & Animals

    This tutorial looks at some of the communities in freshwater lentic habitats. For instance, symbiosis occurs in a commun..

    Selective Breeding
    Selective Breeding

    Gregor Mendel's studies into Monohybrid and Dihybrid crossing and Charles Darwin's study of evolution and natural select..

    Related Articles...

    No related articles found

    See all Related Topics