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单词 chiasma
释义

Definition of chiasma in English:

chiasma

nounPlural chiasmata kʌɪˈazməkɪˈazməkaɪˈæzmə
  • 1Anatomy
    The X-shaped structure formed at the point below the brain where the two optic nerves cross over each other.

    Example sentencesExamples
    • The dura that invests the optic chiasma can be traced from the chiasma along the optic nerve.
  • 2Biology
    A point at which paired chromosomes remain in contact during the first metaphase of meiosis, and at which crossing over and exchange of genetic material occur between the strands.

    Example sentencesExamples
    • Genetic recombination is absent and no chiasmata are formed in bivalents.
    • A given factor s can affect the recombination rate r through a change in the number of chiasmata occurring during meiosis.
    • During meiosis, homologous chromosomes become physically connected by the formation of chiasmata.
    • First, it generates crossovers between homologous chromosomes that mature into visible chiasmata.
    • However, the observed differences may be conditional on the chromosomal location of the chiasmata.

Origin

Mid 19th century: modern Latin, from Greek chiasma 'crosspiece, cross-shaped mark', from khiazein 'mark with the letter chi'.

 
 

Definition of chiasma in US English:

chiasma

nounkīˈazməkaɪˈæzmə
  • 1Anatomy
    The X-shaped structure formed at the point below the brain where the two optic nerves cross over each other.

    Example sentencesExamples
    • The dura that invests the optic chiasma can be traced from the chiasma along the optic nerve.
  • 2Biology
    A point at which paired chromosomes remain in contact during the first metaphase of meiosis, and at which crossing over and exchange of genetic material occur between the strands.

    Example sentencesExamples
    • A given factor s can affect the recombination rate r through a change in the number of chiasmata occurring during meiosis.
    • Genetic recombination is absent and no chiasmata are formed in bivalents.
    • During meiosis, homologous chromosomes become physically connected by the formation of chiasmata.
    • However, the observed differences may be conditional on the chromosomal location of the chiasmata.
    • First, it generates crossovers between homologous chromosomes that mature into visible chiasmata.

Origin

Mid 19th century: modern Latin, from Greek chiasma ‘crosspiece, cross-shaped mark’, from khiazein ‘mark with the letter chi’.

 
 
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更新时间:2025/1/27 21:11:58