Chapter 9.txt

  1. anaphase, mitosis
    Nuclear division stage. Sister chromatids of each chromosome are separated from each other and move to opposite spindle poles.
  2. bipolar mitotic spindle
    Of eukaryotic cells, a dynamic array of microtubules that moves chromosomes with respect to its two poles during mitosis or meiosis.
  3. cancers
    A malignant neoplasm; a mass of abnormally dividing cells that can leave their home tissue and invade and form new masses in other parts of the body.
  4. cell cycle
    Of eukaryotic cells, a series of events from the time a cell forms until it reproduces. A cycle consists of interphase, mitosis, and cytoplasmic division.
  5. cell plate formation
    The mechanism of cytoplasmic division in plant cells. After nuclear division, vesicles derived from Golgi bodies deposit the material for a cross-wall that cuts through the cytoplasm and connects to the parent cell wall.
  6. centrioles
    A barrel-shaped structure that arises from a centrosome and organizes newly forming microtubules into a 9+2 array inside a cilium or flagellum.
  7. centromere
    Of a eukaryotic chromosome, a constricted region having binding sites (kinetochores) for spindle microtubules.
  8. centrosome
    Dense mass of material in the cytoplasm of eukaryotic cells from which microtubules start to grow.
  9. chromosome
    In eukaryotic cells, a linear DNA double helix with many histones and other proteins attached. See also Bacterial chromosome.
  10. chromosome number
    The sum of all of the chromosomes in cells of a given type.
  11. contractile ring mechanism
    Mechanism of cytoplasmic division of animal cells. Just beneath the plasma membrane, a thin band of contractile filaments around the cell midsection contracts and pinches the cytoplasm in two.
  12. cytokinesis
    [Gk. kinesis, motion] Cytoplasmic division.
  13. cytoplasmic division
    Cytokinesis. After nuclear division, a splitting of the parent cell cytoplasm that completes formation of daughter cells.
  14. diploid number
    Of many sexually reproducing species, having two chromosomes of each type, or pairs of homologues, in somatic cells.
  15. germ cells
    Animal cell set aside for sexual reproduction; gives rise to gametes.
  16. growth factors
    A protein that stimulates increases in size; e.g., by inducing mitosis.
  17. HeLa cells
    Cancer cell of a lineage used in research laboratories around the world.
  18. histones
    Type of structural protein that helps organize and condense eukaryotic chromosomes and control access to genes during interphase.
  19. interphase
    In a eukaryotic cell cycle, the interval between mitotic divisions when a cell grows in mass, roughly doubles the number of its cytoplasmic components, and replicates its DNA.
  20. kinases
    Type of enzyme that transfers a phosphate-group to an organic molecule.
  21. kinetochores
    A mass of protein and DNA in the centromere to which microtubules of the spindle attach.
  22. meiosis
    [Gk. meioun, to diminish] A nuclear division process that halves the parental chromosome number, to a haploid (n) number. Prerequisite to the formation of gametes and sexual spores.
  23. metaphase
    Of meiosis I, stage when all pairs of homologues are positioned at the equator of a bipolar spindle. Of mitosis or meiosis II, the stage when all duplicated chromosomes are positioned at the equator.
  24. metastasis
    Abnormal migration of cancer cells that break away from home tissues and may start colonies in other tissues.
  25. microtubules
    Largest cytoskeletal element; a filament of tubulin subunits. Contributes to cell shape, growth, and motion.
  26. mitosis
    [Gk. mitos, thread] Type of nuclear division that maintains the parental chromosome number. The basis of growth in size, tissue repair, and often asexual reproduction for eukaryotes.
  27. neoplasms
    Mass of cells (tumor) that lost control over the cell cycle.
  28. nucleosome
    Small stretch of eukaryotic DNA wound twice around a spool of proteins called histones.
  29. prophase, mitosis
    All of the duplicated chromosomes in a cell condense and get attached to a newly forming spindle.
  30. sister chromatids
    One of the two attached members of a duplicated eukaryotic chromosome.
  31. somatic cells
    [Gk. soma�, body] Any body cell that is not a germ cell.
  32. telophase
    Of meiosis I, a stage when one member of each pair of homologous chromosomes has arrived at a spindle pole. Of mitosis and of meiosis II, the stage when chromosomes typically decondense into threadlike structures and two daughter nuclei form.
  33. tumor
    Tissue mass of cells dividing at an abnormally high rate. Benign tumor cells stay in their home tissue; malignant ones metastasize, or slip away and invade other places in the body, where they may start new tumors. See also neoplasm.
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Chapter 9.txt
Chapter 9