| Term | Definition |
|---|
| Binary Fission | "Dividing in half," a form of reproduction used by prokaryotes. |
| Chromatin | Diffuse mass of long, thin fibers; Chromosomes usually exist in this stage. |
| Chromatid | One of the two identical parts of a duplicated chromosome in a eukaryotic cell. |
| Centromere | Joins two chromatids (sister chromatids) together. |
| Cell Cycle | Ordered sequence of events from the time a cell is formed to its own division into two cells |
| Interphase | The period in the eukaryotic cell when the cell is not actually dividing. |
| Mitotic phase | The part of the cell cycle when the cell actually divides. |
| mitosis | The division of a single nucleus into two genetically identical daughter nuclei. |
| Cytokinesis | The cytoplasm is divided in two. |
| Prophase | The first stage of mitosis, during which the chromatin condenses and the mitotic spindle begins to form, but the nucleus is still intact. |
| Prometaphase | The second stage of mitosis, during which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores (2 kinetochores--1 from each chromatid--make up the centromere) of the sister chromatids. |
| Metaphase | The 3rd 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. |
| Anaphase | The 4th 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. |
| Telophase | The 5th and final stage of mitosis, in which daughter nuclei form at the two poles of a cell. This usually occurs with cytokinesis. |
| Mitotic spindle | football shaped structure of microtubules that guides the separation of the two sets of daughter chromosomes. |
| Cleavage Furrow | Shallow groove in the cell surface that begins the process of cytokinesis. |
| Cell plate | Double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis. |
| anchorage dependence | The requirement that to divide, a cell must be attached to a solid surface. |
| density-dependent inhibition | The arrest of cell division that occurs when cells grown in a laboratory dish touch one another; generally due to an inadequate supply of growth factors. |
| Growth Factor | Protein secreted by certain body cells that stimulates other cells to divide. |
| Cell cycle control system | A cyclically operating set of proteins that triggers and coordinates events in the eukaryotic cell cycle. |
| Cancer cells | Cells that do not respond normally to the cell cycle control system. |
| tumor | An abnormal mass of cells that forms within otherwise normal tissue. |
| benign tumor | An abnormal mass of cells that remains at its original site in the body. |
| malignant rumor | An abnormal tissue mass that can spread into neighboring tissue and to other parts of the body; a cancerous tumor. |
| metastasis | The spread of cancer cells beyond their original site. |
| carcinomas | Cancer that originates in the external or internal coverings of the body, such as skin or the lining of the intestinal tract. |
| sarcomas | Cancer of the supportive tissues, such as bone, cartilage, and muscle. |
| leukemia and lymphoma | Cancers of blood-forming tissues, such as bone marrow. |
| Homologous chromosomes | The two chromosomes that make up a matched pair in a diploid cell; two chromosomes that have the same length, centromere position, and possess the same genes; one of the two chromosomes is inherited from the mother, the other from the father. |
| diploid cell | Any cell with two homologous sets of chromosomes. |
| gamete | A sex cell; a haploid egg or sperm. |
| haploid cell | A cell with a single chromosome set. |
| Meiosis | Type of cell division that produces haploid gametes in diploid organisms. |
| Crossing over | An exchange of corresponding segments between two homologous chromosomes. |
| Chiasma | The site of crossing over. |
| Karyotype | A display of micrographs of the metaphase chromosomes of a cell, arranged by size and centromere location. |
| trisomy 21 | A condition where there are three number 21 chromosomes, making 47 in total; also called "Down's Syndrome." |
| Down syndrome | A person with an extra copy of chromosome 21 has this syndrome |
| 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. |
| Deletion | The loss of one or more nucleotides from a gene by mutation; the loss of a fragment of a chromosome. |
| Duplication | Repetition of part of a chromosome resulting from fusion with a fragment from a homologous chromosome; can result from an error in meiosis of from mutagenesis. |
| Inversion | A change in a chromosome resulting from reattachment of a chromosome fragment to the original chromosome, but in a reverse direction. Mutagens and errors during meiosis can cause inversions. |
| Translocation | 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. |
| sexual reproduction | The creation of offspring by the fusion of 2 hipliod sex cells (gametes), forming a diploid zygote |
| fertilization | The union of the nucleus of a sperm cell with the nucleus of an egg cell, producing a zygote |
| life cycle | A series of stages through which an organism passes between recurrences of a primary stage |
| genome | The ordering of genes in a haploid set of chromosomes of a particular organism |
| asexual reproduction | Reproduction without the fusion of gametes |
| chromosomes | Thread like structures that have genetic info that is passed down from one generation to the next |
| cell division | The process in reproduction and growth by which a cell divides to form daughter cells |
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