Dictionary > Zygotene

Zygotene

Definition
noun, plural: zygotenes
The sub-stage of prophase I of meiosis I in which the homologous chromosomes pair or come together in synapse
Supplement
Meiosis is form of cell division that gives rise to genetically diverse sex cells or gametes. It is comprised to two successive nuclear divisions namely meiosis I and meiosis II. Meiosis I is comprised of four stages: prophase I, metaphase I, anaphase I, and telophase I. Prophase I is the first stage and consists of the following sub-stages: leptotene, zygotene, pachytene, diplotene and diakinesis.
The zygotene is the stage of prophase I that follows after leptotene and precedes pachytene. Prior to zygotene, the chromosomes start to condense into long strands inside the nucleus and the chromosomes appear as threadlike. Zygotene is that phase wherein the homologous chromosomes pair or come together in synapse. The pairing or coming together of homologous chromosomes is called synapsis. It may be facilitated by the synaptonemal complex.
The term zygotene is derived from Greek words that mean paired threads. The pairing is zipper-like in fashion. The pairing may start at any part of the chromosomes, e.g. near the end or near the centromere. The pairing is also highly specific, i.e. homologous chromosomes that come in pairs must be of equal length and have the same centromere position. The paired chromosomes are called bivalent or tetrad chromosomes.
The zygotene stage is also described as bouquet stage since the telomeres cluster at one end of the nucleus.
Word origin: from Ancient Greek words: zygon (junction, yoke) + –tene (filament)
Synonym:

See also:

  • meiosis
  • meiosis I
  • prophase I
  • leptotene
  • pachytene
  • diplotene
  • diakinesis
  • homologous chromosome
  • synaptonemal complex


    You will also like...

    Human Reproduction
    Human Reproduction

    Humans are capable of only one mode of reproduction, i.e. sexual reproduction. Haploid sex cells (gametes) are produced ..

    DNA - schematic
    Genetic Mutations

    This tutorial looks at the mutation at the gene level and the harm it may bring. Learn about single nucleotide polymorph..

    Digestion and Absorption of Food
    Digestion and Absorption of Food

    The gastrointestinal system breaks down particles of ingested food into molecular forms by enzymes through digestion and..

    Early Earth
    The Origins of Life

    This tutorial digs into the past to investigate the origins of life. The section is split into geological periods in the..

    Protein (illustration)
    Protein Variety

    The sequence of amino acids determines the type of protein. Protein is synthesized according to the sequence of nucleoti..

    Nephrolepis exaltata
    Vascular Plants: Ferns and Relatives

    Ferns and their relatives are vascular plants, meaning they have xylem and phloem tissues. Because of the presence of va..