Chapter 12: The Cell Cycle

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anaphase

Back 1

The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell.

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aster

Back 2

A radial array of short microtubules that extends from each centrosome toward the plasma membrane in an animal cell undergoing mitosis.

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cell cycle

Back 3

An ordered sequence of events in the life of a cell, from its origin in the division of a parent cell until its own division into two

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cell division

Back 4

The reproduction of cells.

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cell plate

Back 5

A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.

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centromere

Back 6

The specialized region of the chromosome where two sister chromatids are most closely attached.

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centrosome

Back 7

Structure present in the cytoplasm of animal cells, important during cell division

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chromatin

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The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.

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chromosome

Back 9

A cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each chromosome consists of one very long DNA molecule and associated proteins. (A bacterial chromosome usually consists of a single circular DNA molecule and associated proteins. It is found in the nucleoid region, which is not membrane bounded.) See also chromatin.

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cytokinesis

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The division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II.

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interphase

Back 11

The period in the cell cycle when the cell is not dividing. During interphase, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Interphase accounts for 90% of the cell cycle.

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metaphase

Back 12

The third stage of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate.

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metaphase plate

Back 13

An imaginary plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located.

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mitosis

Back 14

A process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. Mitosis conserves chromosome number by allocating replicated chromosomes equally to each of the daughter nuclei.

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mitotic (M) phase

Back 15

The phase of the cell cycle that includes mitosis and cytokinesis.

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mitotic spindle

Back 16

An assemblage of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis.

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prometaphase

Back 17

The second stage of mitosis, in which discrete chromosomes consisting of identical sister chromatids appear, the nuclear envelope fragments, and the spindle microtubules attach to the kinetochores of the chromosomes.

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prophase

Back 18

The first stage of mitosis, in which the chromatin condenses, the mitotic spindle begins to form, and the nucleolus disappears, but the nucleus remains intact.

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sister chromatids

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Either of two copies of a duplicated chromosome attached to each other by proteins at the centromere and, sometimes, along the arms. While joined, two sister chromatids make up one chromosome

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telophase

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The fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun.