Cell Cycle

G0 Phase

Definition - A non dividing phase of the cell cycle consisting of the portion of interphase before DNA synthesis begins

Centromere

Definition - A specialized condensed region of each chromosome that appears during mitosis where the chromatids are held together to form an X shape.

Aneuploidy

Definition - An abnormality involving a chromosome number that is not an exact multiple of the haploid number (one chromosome set is incomplete). Example: cancer cells are this (abnormal number of chromosomes)

Diploid

Definition - An organism or cell having two sets of chromosomes or twice the haploid number. Example: human skin/muscles cells are this (a cell having two sets of chromosomes)

Haploid/Monoploid

Definition - Describes a cell, nucleus, or organism that has only one set of unpaired chromosomes. Example: human sperm/egg cells are this (a cell that has only one set of chromosomes)

Spindle Fibers

Definition - Fibers that appear during mitosis. Chromosomes attach to the spindle fibers at the centromere and move back and forth between the poles on the fibers.

Sister Chromatids

Definition - Identical copies of a chromosome; full sets of these are created during the S(DNA replication) subphase of interphase.

Centrioles

Definition - One of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope; play a role in cell division.

Telophase

Definition - The final stage of meiosis or mitosis, in which the separated chromosomes reach the opposite poles of the dividing cell and the nuclei of the daughter cells form around the two sets of chromosomes.

G1 Phase

Definition - The first growth phase of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.

Interphase

Definition - The phase of the cell cycle in which the cell spends the majority of its time and performs the majority of its purposes including preparation for cell division.

M Phase

Definition - The phase of the cell cycle that includes mitosis and cytokinesis. Compare/Contrast: When a cell has reaced the G0 Phase, it has left the cycle and will never divide. M Phase includes mitosis and cytokinesis, where the division of the cell takes place.

G2 Phase

Definition - The second growth phase of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs. Compare/Contrast: G1 is a phase before DNA synthesis begins, where the cell grows. It is the first stage of interphase. G2 phase is where the cell grows again, and prepares for mitosis. This occurs after DNA synthesis takes place.

Metaphase

Definition - The second phase of mitosis, during which the chromosomes line up across the center of the cell.

Anaphase

Definition - The third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles.

Interkinesis

Definition - This is the stage between the first stage of meiosis and the second stage of meiosis. No DNA replication occurs here. Example: many plant cells skip this phase (period between meiosis I and meiosis II, when no DNA replication takes place)