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

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.