Cell Division
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Created by:
dkoons on January 7, 2011
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Classes:
Bio101Powers, General Biology, Honors Biology
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67 terms
Terms | Definitions |
|---|---|
 chromosomes | threadlike structures made of DNA molecules that contain the genes |
| cell division | the process in reproduction and growth by which a cell divides to form daughter cells |
| binary fission | a form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size |
| chromatin | The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, its genetic material exists as a mass of very long, thin fibers that are not visible with a light microscope. |
| sister chromatids | Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II. |
| centromere | the region of the chromosome that holds the two sister chromatids together during mitosis |
| cell cycle | series of events that cells go through as they grow and divide |
| interphase | a period of time when the cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases |
| mitotic phase (M phase) | The phase of the cell cycle that includes mitosis and cytokinesis. |
| mitosis | cell division in which the nucleus divides into nuclei containing the same number of chromosomes |
| cytokinesis | process by which the cytoplasm of a cell is divided in two; usually follows mitosis and meiosis |
| prophase | first and longest phase of mitosis, during which the chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus |
| metaphase | second phase of mitosis, during which the chromosomes line up across the center of the cell |
| anaphase | the third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles |
| telophase | the final stage of mitosis during which a nuclear membrane forms around each set of new chromosomes |
| mitotic spindle | An assemblage of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis. |
| kinetochore | A specialized region on the centromere that links each sister chromatid to the mitotic spindle. |
| cleavage furrow | the area of a cell membrane that pinches inward during animal cell mitosis eventually dividing the cell |
| cell plate | the precursor of a new plant cell wall that forms during cell division and divides a cell into two |
| anchorage dependence | the requirement that to divide, a cell must be attached to a solid surface. |
| density-dependent inhibition | The phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another. |
| growth factor | broad group of proteins that stimulate cell division. |
| cell cycle control system | A cyclically operating set of molecules in the cell that triggers and coordinates key events in the cell cycle. |
| cancer cells | Do not have a properly functioning cell-cycle system; instead, they divide excessively and can invade other tissues of the body |
| tumor | an abnormal mass of tissue that can live and reproduce itself, but performs no service to the body |
| benign tumor | an abnormal mass of cells that remains at its original site in the body and is not cancerous |
| malignant tumor | an abnormal tissue mass that can spread into neighboring tissue and to other parts of the body; a cancerous tumor |
| metastasis | the process by which cancer cells are spread by blood or lymph circulation to distant organs |
| carcinomas | cancers that originate in the external or internal coverings of the body (i.e. skin, body chamber linings, and glands) |
| sarcomas | Cancers that arise in the connective tissue cells, including bones, ligaments, and muscles. |
| leukemias and lymphomas | Cancers of blood-forming tissues, such as bone marrow, spleen, and lymph nodes |
| homologous chromosomes | Chromosomes that are similar in size, shape, and genetic content |
| sex chromosomes | Chromosomes that determine the sex of an individual; different for each sex |
| autosomes | chromosomes that are not directly involved in determining the sex of an individual; same for each sex |
| diploid | an organism or cell having two sets of chromosomes or twice the haploid number |
| haploid | of a cell or organism having a single set of chromosomes |
| gametes | an organism's reproductive cells, such as sperm or egg cells |
| zygote | The diploid product of the union of haploid gametes in conception; a fertilized egg. |
| meiosis | a process in cell division during which the number of chromosomes decreases to half the original number by two divisions of the nucleus, which results in the production of sex cells |
| prophase I | The first phase of meiosis I. During this phase the replicated chromosomes condense, homologous chromsomes pair up, crossing over occurs between homologous chromosomes, the spindle is formed, and the nuclear envelope breaks apart into vesicles. |
| metaphase I | The second phase of meiosis I. During this phase the paired homologous chromsomes (tetrads) align at the center of the cell (the metaphase plate). |
| anaphase I | The third phase of meiosis I. During this phase the replicated homologous chromosomes are separated (the tetrad is split) and pulled to opposite sides of the cell. |
| telophase I | The fourth of meiosis I. During this phase replicated homologous chromosomes are at the poles of the cell and a nuclear membrane forms around each set. Usually, cytokinesis occurs along with this phase resulting in two haploid cells. Note however, that the chromosomes are still replicated, and the sister chromatids must still be separated during meiosis II. |
| prophase II | The first phase of meiosis II. This phase is identical to mitotic prophase, except that the number of chromosomes was reduced by half during meiosis I. |
| metaphase II | The second phase of meiosis II. This phase is identical to mitotic metaphase, except that the number of chromosomes was reduced by half during meiosis I. |
| anaphase II | The third phase of meiosis II. During this phase the sister chromatids are finally spearated at their centromeres and puled to opposite sides of teh cell. Note that this phase is identical to mitotic anaphase, excep the number of chromosmes was reduced by half during meiosis I. |
| telophase II | The fourth and final phase of meiosis II. This phase is identical to mitotic telophase, except that the number of chromosomes was reduced by half during meiosis. I. |
| crossing over | exchange of genetic material between homologous chromosomes during prophase I of meiosis |
| chiasma | a point of overlap of paired chromatids at which fusion and exchange of genetic material occurs during prophase I of meiosis |
| tetrad | the four chromatids in a pair of homologous chromosomes that come together as a result of synapsis during meiosis |
| synapsis | the side by side pairing of homologous maternal and paternal chromosomes at the start of meiosis |
| karyotype | photographic display of the chromosomes found in an individual's cells at metaphase of mitosis and arranged in homologous pairs and in order of diminishing size |
| Down Syndrome | A human genetic disease resulting from having an extra chromosome 21, characterized by mental retardation and heart and respiratory defects. |
| trisomy 21 | condition in which an individual has three number 21 chromosomes, resulting in Down syndrome |
| nondisjunction | error in meiosis in which homologous chromosomes don't separate; gametes end up with wrong number of chromosomes |
| Klinefelter Syndrome | syndrome in males that is characterized by small testes and long legs and enlarged breasts and reduced sperm production and mental retardation |
| Turner Syndrome | Chromosome disorder in females. a x chromosome is missing or part of one x is deleted. short stature and webbed neck. |
| duplication mutation | a chromosmome fragment attaches to its homologous chromosome, which will then carry two copies of a certain set of genes |
| deletion mutation | Chromosome mutation in which a piece of chromosome is broken off and lost. |
| inversion mutation | Mutation in which a chromosome piece reattaches to original chromosome but in reverse orientation |
| translocation mutation | Chromosome mutation in which a broken pice reattaches to a non homologus chromosome. |
| G1 check point | If the cell gets the "go ahead" signal at this point, it normally completes the entire cell cycle and divides. If not, the cell enters a non-dividing phase known as G0. Some cells remain in this phase while others can be stimulated to reenter the cycle. |
| G2 check point | assess if DNA replication has been successful, if yes proceed to mitosis |
| M check point | between metaphase and anaphase all chromosome must be attached to the spindle, if yes proceed with mitosis |
| G1 phase | in interphase - cell grows rapidly, builds new organelles |
| S phase | The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated. |
| G2 phase | when DNA is replicated the cell enters this phase, many organelles and molecules required for cell division are produced |
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