Chapter 8 - Modern Biology
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hfinnerty15 on May 11, 2012
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45 terms
Terms | Definitions |
|---|---|
 Chromosomes | rod-shaped structured made of DNA and proteins |
| Histones | proteins that DNA in eukaryotes wrap around - help maintain the shape of DNA |
| Chromatid | a half of a chromosome - form as the DNA copies itself before cell divison |
| Centromere | the point where the two chromatids of a chromsome are attached |
| Chromatin | the less tightly coiled DNA |
| Sex Chromosomes | chromsomes that determine the sex of an organism - one pair of chromosomes |
| Autosomes | 22 pairs of chromosomes - not sex chromsomes |
| Homologous Chromosomes | two copies of each autosome - are the same size, shape, and carry genes for the same traits |
| Karyotype | a photomicrograph of the chromosomes ina dividing cell |
| Diploid | cells that have two sets of chromosomes |
| Haploid | cells that have only one set of chromosomes - ex. sperm and egg cells |
| Binary Fission | the division of a prokaryotic cell - DNA is copied, the cell divides, which creates two identical haploid cells |
| Asexual Reproduction | the production of offspring from one parent |
| Gametes | Haploid reproductive cells |
| Cell Cycle | a repeating set of events in the life of a cell - includes interphase and cell division |
| Interphase | the time between each cell division in the cell cycle - includes G1, S, and G2 phases |
| Cell Division | the part of the cell cycle occuring before interphase - includes mitosis and cytokinesis |
| Cytokinesis | the division of the cell's cytoplasm by pinching inward of the cells membrane |
| G1 Phase | the phase of interphase in which offspring cells grow to a mature size |
| S Phase | the phase of interphase in which the cell's DNA and chromosomes are copied |
| G2 Phase | the phase of interphase in which the cell prepares for cell division |
| G0 Phase | the phase of interphase in which the cell exits cell division and do not prepare for cell division |
| Mitosis | the division of a cell's nucleus in cell division |
| Prophase | the stage of mitosis in which DNA is coiled tightly - the nuclear membrane and envelope dissolve - spindle fibers assemble |
| Spindle Fibers | fibers made of microtubules that radiate from the centrosomes on either side of the cell in preparation for metaphase |
| Mitotic Spindle | an array of spindle fibers that equally divide chromatids between the two offspring cells |
| Kinetochore Fibers | are attached to a protein in the centromere of each chromosome and reach out and attach to one of the centrosomes |
| Polar Fibers | extend across the cell from centosome to centrosome but dont attach to the chromosomes |
| Metaphase | the stage of mitosis in which kinetochore fibers move chromsomes to the center of the cell - karyotypes are made in this stage |
| Anaphase | the stage of mitosis in which the chromatids of each chromosome separate at the centromere and move towards opposite poles of the cell |
| Telophase | the stage of mitosis in which the spinder fibers disassemble - chromosomes uncoil - nuclear envelopes and nucleoli form |
| Cleavage Furrow | the area of the cell membrane that pinches in and separates the cells (in animal cells) |
| Cell Plate | vesicles from the Golgi Apparatus join together in the midline of the dividing cell and create this (only in plant cells) |
| G1 Checkpoint | growth checkpoint - the checkpoint after the G1 phase where the cell decides whether the cell is healthy and large enough to divide |
| G2 Checkpoint | DNA synthesis checkpoint - the checkpoint after the G2 phase where enzymes check that the duplication of DNA |
| Mitosis Checkpoint | the checkpoint after mitosis that signals the cell to exit mitosis and enter cytokinesis |
| Meiosis | the cell division of gametes |
| Synapsis | the pairing of homologous chromosomes |
| Tetrad | a pair of homologous chromosomes |
| Crossing Over | the breaking off of portions of chromosome and the reattachment of them on their homologous chromosome |
| Genetic Recombination | the exchange of genetic material between maternal and paternal chromosomes to make a new mixture of genetic material |
| Independent Assortment | the random separation of homologous chromosomes |
| Spermatogenesis | the production of sperm cells |
| Oogenesis | the production of mature egg cells |
| Polar Bodies | in oogenesis - the three left over products of meiosis - eventually degenerate |
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