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BIOL 114
Ch 8: Cellular Reproduction: Cells from Cells
Term | Definition |
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anaphase | The third stage of mitosis, beginning when sister chromatids separate from each other and ending when a complete set of daughter chromosomes has arrived at each of the two poles of the cell. |
asexual reproduction | The creation of genetically identical offspring by a single parent, without the participation of gametes (sperm and egg). |
Autosome | A chromosome not directly involved in determining the sex of an organism; in mammals, for example, any chromosome other than X or Y. |
benign tumor | An abnormal mass of cells that remains at its original site in the body. |
cancer | A malignant growth or tumor caused by abnormal and uncontrolled cell division. |
cell cycle | An ordered sequence of events (including interphase and the mitotic phase) that extends from the time a eukaryotic cell is first formed from a dividing parent cell until its own division into two cells. |
cell cycle control system | A cyclically operating set of proteins that triggers and coordinates events in the eukaryotic cell cycle. |
cell division | The reproduction of a cell. |
cell plate | A membranous disk that forms across the midline of a dividing plant cell. During cytokinesis, the cell plate grows outward, accumulating more cell wall material and eventually fusing into a new cell wall. |
centromere | The region of a chromosome where two sister chromatids are joined and where spindle microtubules attach during mitosis and meiosis. The centromere divides at the onset of anaphase during mitosis and anaphase II of meiosis. |
Centrosome | Material in the cytoplasm of a eukaryotic cell that gives rise to microtubules; important in mitosis and meiosis; functions as a microtubule-organizing center. |
Chemotherapy | Treatment for cancer in which drugs are administered to disrupt cell division of the cancer cells. |
chiasma | The microscopically visible site where crossing over has occurred between chromatids of homologous chromosomes during prophase I of meiosis. |
chromatin | The combination of DNA and proteins that constitutes chromosomes; often used to refer to the diffuse, very extended form taken by the chromosomes when a eukaryotic cell is not dividing. |
chromosome | A gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell. Each chromosome consists of one very long threadlike DNA molecule and associated proteins. See also chromatin. |
cleavage furrow | The first sign of cytokinesis during cell division in an animal cell; a shallow groove in the cell surface near the old metaphase plate. |
cross | The cross-fertilization of two different varieties of an organism or of two different species; also called hybridization. |
crossing over | The exchange of segments between chromatids of homologous chromosomes during prophase I of meiosis. |
cytokinesis | The division of the cytoplasm to form two separate daughter cells. Cytokinesis usually occurs during telophase of mitosis, and the two processes (mitosis and cytokinesis) make up the mitotic (M) phase of the cell cycle. |
diploid | Containing two sets of chromosomes (homologous pairs) in each cell, one set inherited from each parent; referring to a 2n cell. |
Down syndrome | A human genetic disorder resulting from the presence of an extra chromosome 21; characterized by heart and respiratory defects and varying degrees of mental retardation. |
fertilization | The union of a haploid sperm cell with a haploid egg cell, producing a zygote. |
Gamete | A sex cell; a haploid egg or sperm. The union of two gametes of opposite sex (fertilization) produces a zygote. |
genetic recombination | The production of offspring with gene combinations that differ from that found in either parent. |
haploid | Containing a single set of chromosomes; referring to an n cell. |
Histone | A small protein molecule associated with DNA and important in DNA packing in the eukaryotic chromosome. |
homologous chromosomes | The two chromosomes that make up a matched pair in a diploid cell. Homologous chromosomes are of the same length, centromere position, and staining pattern and possess genes for the same characteristics at corresponding loci. One homologous chromosome is inherited from the organism's father, the other from the mother. |
interphase | The phase in the eukaryotic cell cycle when the cell is not actually 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. See also mitosis. |
karyotype | A display of micrographs of the metaphase chromosomes of a cell, arranged by size and centromere position. |
life cycle | The entire sequence of stages in the life of an organism, from the adults of one generation to the adults of the next. |
malignant tumor | An abnormal tissue mass that spreads into neighboring tissue and to other parts of the body; a cancerous tumor. |
Meiosis | In a sexually reproducing organism, the division of a single diploid cell into four haploid daughter cells. Meiosis and cytokinesis produce haploid gametes from diploid cells in the reproductive organs of the parents. |
metaphase | The second stage of mitosis. During metaphase, the centromeres of all the cell's duplicated chromosomes are lined up on an imaginary plate equidistant between the poles of the mitotic spindle. |
metastasis | The spread of cancer cells beyond their original site. |
mitosis | The division of a single nucleus into two genetically identical daughter nuclei. Mitosis and cytokinesis make up the mitotic (M) phase of the cell cycle. |
mitotic (M) phase | The phase of the cell cycle when mitosis divides the nucleus and distributes its chromosomes to the daughter nuclei and cytokinesis divides the cytoplasm, producing two daughter cells. |
mitotic spindle | A spindle-shaped structure formed of microtubules and associated proteins that is involved in the movement of chromosomes during mitosis and meiosis. (A spindle is shaped roughly like a football.) |
nondisjunction | An accident of meiosis or mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to separate at anaphase. |
nucleosome | The bead-like unit of DNA packing in a eukaryotic cell; consists of DNA wound around a protein core made up of eight histone molecules. |
prophase | The first stage of mitosis. During prophase, duplicated chromosomes condense to form structures visible with a light microscope, and the mitotic spindle forms and begins moving the chromosomes toward the center of the cell. |
radiation therapy | Treatment for cancer in which parts of the body that have cancerous tumors are exposed to high-energy radiation to disrupt cell division of the cancer cells. |
Sex chromosome | A chromosome that determines whether an individual is male or female; in mammals, for example, the X or Y chromosome. |
Sexual reproduction | The creation of genetically distinct offspring by the fusion of two haploid sex cells (gametes: sperm and egg), forming a diploid zygote. |
sister chromatid | One of the two identical parts of a duplicated chromosome. While joined, two sister chromatids make up one chromosome; chromatids are eventually separated during mitosis or meiosis II. |
somatic cell | Any cell in a multicellular organism except a sperm or egg cell or a cell that develops into a sperm or egg; a body cell. |
telophase | The fourth and final stage of mitosis, during which daughter nuclei form at the two poles of a cell. Telophase usually occurs together with cytokinesis. |
tumor | An abnormal mass of cells that forms within otherwise normal tissue. |
zygote | The fertilized egg, which is diploid, that results from the union of haploid gametes (sperm and egg) during fertilization. |