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| a threadlike, 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. Chromosomes consist of a chromatin. |
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| the reproduction of a cell. |
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| a means of asexual reproduction in which a parent organism, often a single cell, divides into two individual sof about equal size. |
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| 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. |
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| one of the two identical parts of a duplicated chromosome in a eukaryotic cell. |
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| 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 during meiosis. |
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| 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. |
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| the period in the eukaryotic cell cycle when the cell is not actually dividing. |
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| the part 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. |
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| 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. |
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| the division of the cytoplasm to form two seperate daughter cells. Cytokinesis usually occurs during telophase of mitosis, and mitosis an dcytokinesis make up the mitotic (M) phase of the cell cycle. |
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| the first stage of mitosis, during which the chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still intact. |
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| the second stage of mitosis, during which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the sister chromatids. |
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| the third stage of mitosis, during which all the cell's duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle. |
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| the fourth stage of mitosis, beginning when sister chromatids separate from each other and ending when a complete set of daughter chromosomes have arrived at each of the two poles of the cell. |
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| the fifth and final stage of mitosis, during which daughter nuclei form at the two poles of a cell. Telophase usually occurs together with cytokinesis. |
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| a spindle-shaped structure formed of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis and meiosis. (A spindle is shaped roughly like a football. |
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| material in the cytoplasm of a eukaryotic cell that gives rise to microtubules; important in mitosis and meiosis; also called microtubule-organizing center. |
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| the first sign of cytokinesis during cell division in an animal cell; a shallow groove in the cell surface near the old mataphase plate. |
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| a double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis. |
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| the requirement that to divide, a cell must be attached to a solid surface. |
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| density-dependent inhibition |
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| the arrest of cell divisiont hat occurs when cells grown in a laboratory dish touch one another; generally due to an inadequate supply of growth factors. |
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| a protein secreted by certain body cells that stimulates other cells to divide. |
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cell cycle control system |
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| a cyclically operating set of protiens that triggers and coordinates events in the eukaryotic cell cycle. |
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| a cell that is not subject to normal cell cycle control mechanisms and that will therefore divide continuously. |
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| an abnormal mass of cells that forms within otherwise normal tissue. |
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| an abnormal mass of cells that remains at its original site in the body. |
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| an abnormal tissue mass that can spread into neighboring tissue and to other parts of the body; a cancerous tumor. |
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| the spread of cancer cells beyond their original site. |
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| cancer that originates in the coverings of the body; such as skin or the lining of the intestinal tracts. |
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| cancer of the supportive tissues, such as bone, cartilage, and muscle. |
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a type of cancer of the blood-forming tissues, characterized by an excessive production of white blood cells and an abnormaly high number of them in the blood; cancer of the bone marrow cells that produce leukocytes. |
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| cancer of the tissues that form white blood cells. |
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| any cell in a multicellular organism except a sperm or egg cell or a cell that developes into sperm or egg. |
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| 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 alleles for the same genes at corresponding loci. One homologus chromoe is inherited from the organisms's father, the other from the mother. |
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| the particular site where a gene is found on a chromosome. Homologous chromosomes have corresponding gene loci. |
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Definition
a threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meioisis; also, the main gene-carrying structure of a prokaryotic cell. Chromosomes consist of chromatin. |
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| a chromsome not directly involved in determining the sex of an organism; in mammals, for example, any chromosome other than X or Y. |
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| in an organism that reproduces sexually, a cell containing two homologous sets of chromosomes, one set inherited from eaach parent; a 2n cell. |
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a sex cell; a haploid egg or sperm. The union of two gametes of opposite sex (fertilization) produces a zygote. |
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| In the life cycle of an organism that reproduces sexually a cell containing a single set of chromosomes; an n cell. |
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The fertilized egg, which is diploid that results from the union of a sperm cell nucleus and an egg cell nucleus. |
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In a sexually reproducing organism, the division of a single diploid nucleus into four haploid daughter nuclei. Meiosis and cytokinesis produce haploid gametes from diploid cells in the reproductive organs of the parents. |
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The exchange of segments between chromatids of homologous chromosomes during synapsis on prophase I of meiosis; also the exchange of segments between DNA molecules in prokaryotes. |
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The microscopically visible site where crossing over has occurred between chromatids of homologous chromosomes during prophase I of meiosis. |
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| The production by crossing over and/or independent assortment of chromosomes during meisosis, of offspring with allele combinations different from those in the parents. The term may also be used more specifically to mean the production by crossing over of eukaryotic or prokaryotic chromosomes with gene combinations different from those in the original chromosomes. |
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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. |
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An accident of meiosis or mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to separate at anaphase. |
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The loss of one or more nucleotides from a gene by mutation; the loss of a fragment of a chromosome. |
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Repetition of part of a chromosome resulting from fusion with a fragment from a homologous chromosome; can result from an error in meiosis or from mutagenesis. |
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A change in a chromosome resulting from a reattachment of a chromosome fragment to the original chromosome, but in a reverse direction. Mutagens and errors during meisosis can cause inversions. |
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Definition
1) During protein synthesis, the movement of a tRNA molecule carrying a growing polypeptide chain from the A site to the P site on a ribosome. (The mRNA travels with it) 2) A change in a chromosome resulting from a chromosomal fragment attaching to a nonhomologous chromosome; can occur as a result of an error in meiosis or from mutagenesis. |
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| a display of micrographs of the metaphase chromosomes of a cell, arranged by size and centromere position. |
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