Bio Ch 12
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Created by:
brookeheitzman on November 12, 2010
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28 terms
Terms | Definitions |
|---|---|
 binary fission | a method of asexual reproduction by "division in half". In prokaryotes, binary fission does not involve mitosis; but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process. |
| cell plate | during telophase, vesicles derived from the Golgi appartus move along microtubules to the middle of the cell, where they coalesce. |
| centrosome | a subcellular region containing material that functions throughout the cell cycle to organize the cells microtubules |
| centromere | the narrow "waist" on the duplicated chromosome. a specialized region where the two chromatids are most closely attached. |
| chromatin | a complex of DNA and associated protein molecules. |
| chromosome | the reason replication and distribution of DNA is manageable. DNA molecules are packaged into chromosomes. |
| kinetochore | a structure of proteins associated with specific sections of chromosomal DNA at the centromere. the two chromosomes kinetochores face in opposite directions. during prometaphase, some of the spindle microtubules attach to them. the chromosome is pulled in opposite directions and eventually they line up on the metaphase plate after tug of war. |
| MPF (maturation-promoting factor") | cyclin-Cdk complex in animals cells that acts at the G2 checkpoint as a go-ahead signal, triggering the events of mitosis. MPF promotes mitosis by phosphorylating various proteins. |
| mitotic (M) phase | includes both mitosis and cytokinesis is usually the shortest part of the cell cycle |
| interphase | 90% of the cell cycle. the cell grows and copies its chromosomes in preparation for cell division. |
| G1 phase & G2 phase | first and second gap of interphase. the cell grows by producing proteins and cytoplasmic organelles such as mtrochondria and ER |
| S phase | synthesis phase of interphase. chromosomes are duplicated only during the S phase. takes up most time of interphase. |
| prophase | chromatin fibers become tightly coiled. chromosomes become joined to their sister chromatids. nucleoli disappears. mitotic spindles begin to form. |
| prometaphase | nuclear envelope fragments. chromosomes become more condensed. each chromatid now has a kinetochore. some binding of microtubules to kinetochores. |
| metaphase | longest stage of mitosis. centrosomes are now at opposite poles. chromosomes align on metaphase plate. each chromatids kintochore is attached to spindle fibers and tug of war begins. |
| anaphase | shortest stage. sister chromatids separate into daughter chromosomes. daughter chromosomes begin to move toward opposite poles (more centromere first). the cell elongates as the nonkinetochore microtubules lengthen. at the end, the two ends of the cell are equivalent- and complete - collections of chromosomes |
| telophase | two daughter nuclei from in the cell. nuclear envelopes arise from the past broken fragments. nucleoli reappear. chromosomes become less condense. |
| cytokinesis | the division of the cytoplasm is usually well underway during telophase, so the two daughter cells appear shortly after the end of mitosis. in animal cells, cytokinesis involves the formation of a cleavage furrow, which pinches the cell into two. |
| aster | a radial array of short microtubules that extend from each centrosome |
| Gary Borisy | motor proteins walk kinetochore microtubules and pull daughter chromosomes closer |
| nonkinetochore microtubles | these microtubules are responsible for elongating the whole cell during anaphase. |
| Paul Nurse | demonstrated the crucial function of the protien kinase Cdc2 in triggering mitosis at the G2 checkpoint in one type of yeast. |
| cyclin | a protein that gets its name from it's cyclically fluctuating concentration in the cell. activates a kinase. |
| cyclin-Cdk | are of major importance in controlling all the stages of the cell cycle. |
| cancer cells | do not stop dividing when the growth factor is used up. they divide at random points in the cycle. the are "immortal". this problem begins when a single cell in a tissue undergoes transformation. |
| benign tumor | a group of abnormal cells that remain at the original site. most do not cause serious problems and can be completely removed by surgery. |
| malignant tumor | a group of abnormal cells that become invasive enough to impair the functions of one or more organs in its original site. those who have this, are said to have cancer. |
| metastasis tumor | the spread of cancer cells to locations distant from the original site. |
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