Biology Chapter 9
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56 terms
Terms | Definitions |
|---|---|
 asexual | single cell or group of cells duplicates its genetic material and then splits into 2 new genetically identical cells |
| sexual | genetic material from each of the two "parents" combines producing offspring that differ genetically from either parent |
| somatic cells | body cells |
| chromatin | mass of long fibers comprosed of DNA & protein molecules (to thin to see) |
| chromosomes | chromatin fibers condense and now visible |
| centromere | region where 2 sister chromatids are joined tightly together |
| three major stages of mitosis | Interphase, Mitotic, cytokinesis |
| interphase | period of cell growth DNA synthesis and preperation for cell division |
| G1 | assembles structures & organelles |
| S | duplicates genetic material; so at the end each cell has two sets |
| G2 | phase in which a cell prepares itself for cell division |
| interphase | chromosomes NOT visivle, prepares for cell division begins when cell reproduction is completed, nucleoulus is still present |
| prophase | 1st phase of mitosis, chromatin begin to coil, nuclear membrane begins to dissolve, 2 pairs of centrioles seperate & move to the opposite poles of the cell, microtubules form in between the centrioles and become spindle fibers |
| metaphase | 2nd stage of mitosis, chromosomes become attached to the spindle fibers, chromosomes line up along the equator |
| anaphase | 3rd stage of mitosis, paired chromatids are pulled apart at the centromer & move to opposite poles and ends w/ one set of single-stranded chromosomes at each end of the cell |
| telophase | 4th stage of mitosis, chromosomes begin to uncoil, nuclear membrane begins to refrom, 2 cells begin to from from one and nucleoli reappears |
| cytokinensis | division of cytoplasm and 2 daughter cells are formed |
| animal cytokinensis | cleavage furrow |
| plant cytokinensis | cell plate |
| cancer | rapid, uncontrolled division of one kind of cell that invades and disrupts cells in other tissues |
| tumor | mass of cells caused by out-of-control cell reproduction |
| benign tumor | an abnormal mass of non-agressive cells and remain at their site of origin in the body |
| malignant tumor | mass of cells that result from rapid reproduction of cancer cells and able to spread into surronding tissue |
| metastasis | able to split off from tumor & travel to other parts of the body to form new tumors |
| oncogenes | stiumulate cell division excessively |
| tumor suppressor genes | inhibit cell division and or cause cell suicide |
| carcinogenes | cancer causing agents |
| radiation | disrupts cell division with energy radiation |
| chemotherapy | disrupt cell division by taking drugs |
| antimotic drugs | prevent cell division by interfering w/ mitotic spindle |
| meiosis | type of cell division that produces four cells, each half of # of chromosomes as parent |
| gamete | sex cell |
| homologous | one of a matching pair of chromosomes one inherited from each parent |
| karyotype | display of chromosomes |
| female | xx |
| male | xy |
| 23rd pair of chromosomes | determines a person's sex |
| haploid | single set of chromosomes |
| diploid | double set of chromosomes |
| fertilization | fusion of gametes |
| zygote | fertilized egg |
| Prophase I | nucleoli & nuclear membrane disappear, centrioles move apar & spindle form |
| tetrad | pairing of replicated homologous chromosomes |
| metaphase I | tetrads move to the equator |
| anaphase I | one duplicate homologous chromosome of each pair moves toward opposite poles and the cell membrane pinches in |
| telophase I & cytokinesis | cytoplasm divides to form two haploid daughter cells. Sister chromatids are still joined |
| meiosis I | chromosomes replicate during interphase before meiosis begins, homologus chromosomes pair up then seperate and two haploid cells are produced |
| meiosis II | sister chromatids separate, begins after a brief interphase |
| prophase II | new spindle fibers form |
| metaphase II | chromosomes move to equator |
| anaphase II | centromeres split and sister chromatids sperate and move to the poles |
| telophase II & cytokinesis | nuclei reform and ends with 4 haploid daughter cells, gentically diff. from each other & parent cell |
| mitosis | 2 diploid daughter cells |
| meiosis | 4 haploid daughter cells |
| sexual reproduction | more genetic variablity due to the randomness of meiosis & so does crossing over |
| asexual reproduction | guaranteed reproduction, no partner & faster |
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