equatorial division

(noun)

a process of nuclear division in which each chromosome divides equally such that the number of chromosomes remains the same from parent to daughter cells

Related Terms

  • ploidy
  • reduction division

Examples of equatorial division in the following topics:

  • Comparing Meiosis and Mitosis

    • Mitosis and meiosis are both forms of division of the nucleus in eukaryotic cells.
    • The nuclei resulting from a mitotic division are genetically identical to the original nucleus.
    • For this reason, meiosis I is referred to as a reduction division.
    • Meiosis II is much more similar to a mitotic division.
    • Meiosis II is, therefore, referred to as equatorial division.
  • Meiosis I

    • In nearly all species of animals and some fungi, cytokinesis separates the cell contents via a cleavage furrow (constriction of the actin ring that leads to cytoplasmic division).
    • Two haploid cells are the end result of the first meiotic division.
    • In this case, there are two possible arrangements at the equatorial plane in metaphase I.
  • The Mitotic Phase and the G0 Phase

    • The first portion of the mitotic phase is called karyokinesis or nuclear division.
    • Karyokinesis, also known as mitosis, is divided into a series of phases (prophase, prometaphase, metaphase, anaphase, and telophase) that result in the division of the cell nucleus .
    • During metaphase, the "change phase," all the chromosomes are aligned in a plane called the metaphase plate, or the equatorial plane, midway between the two poles of the cell.
    • Cytokinesis, or "cell motion," is the second main stage of the mitotic phase during which cell division is completed via the physical separation of the cytoplasmic components into two daughter cells.
    • Division is not complete until the cell components have been apportioned and completely separated into the two daughter cells.
  • Steroids

    • This fixed orientation influences chemical reactivity, largely due to the greater steric hindrance of axial groups versus their equatorial isomers.
    • Thus an equatorial hydroxyl group is esterified more rapidly than its axial isomer.
    • Each chair is fused to the other by equatorial bonds, leaving the angular hydrogens (Ha) axial to both rings.
    • In the conformer on the right, the carbon bond to C-1 is equatorial and the bond to C-6 is axial.
    • Each of the angular hydrogens (Hae or Hea) is oriented axial to one of the rings and equatorial to the other.
  • Glycosides

    • From the structures in the concept, we see that pyranose rings prefer chair conformations in which the largest number of substituents are equatorial.
    • In the case of glucose, the substituents on the beta-anomer are all equatorial, whereas the C-1 substituent in the alpha-anomer changes to axial.
    • Since substituents on cyclohexane ring prefer an equatorial location over axial (methoxycyclohexane is 75% equatorial), the preference for alpha-glycopyranoside formation is unexpected, and is referred to as the anomeric effect.
  • The Bantu Migration

    • The primary evidence for this expansion has been linguistic, namely that the languages spoken in Sub-Equatorial Africa are remarkably similar to each other.
    • They were probably due to denser population, which led to more specialized divisions of labor, including military power, while making outmigration more difficult.
  • Applying the VSEPR Model

    • For example, in a PCl5 molecule, three of the chlorine atoms are in the central phosphorus atom's plane (equatorial positions), while the other two atoms are above and below this plane (axial positions).
    • Equatorial and axial atoms have different geometrical relationships to their neighbors, and thus differ slightly in their chemical behavior.
    • All the ligands are geometrically equivalent with bond angles of 90°; there are no separate axial and equatorial positions.
    • The equatorial atoms have bond angles of 120°.
    • The axial atoms are 90° away from the equatorial atoms.
  • Imperialism and Racial Divisions

  • Beams and Borrowed Divisions

    • Part of this includes grouping the rhythms such that they convey the beat unit and the beat division.
    • Beams are used to group any notes at the beat division level or shorter that fall within the same beat.
    • Typically, a meter is defined by the presence of a consistent beat division: division by two in simple meter, and by three in compound meter.
    • Occasionally, composers will use a triple division of the beat in a simple meter, or a duple division of the beat in a compound meter.
    • Triplets are borrowed from compound meter, and may occur at both the beat division and subdivision levels, as seen below.
  • Burkitt's Lymphoma

    • It is named after Denis Parsons Burkitt, a surgeon who first described the disease in 1956 while working in equatorial Africa.
    • Endemic: This variant occurs in equatorial Africa.
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