Best Results From Wikipedia Yahoo Answers Youtube
Metaphase, from the ancient GreekÎ¼ÎµÏ„Î¬ (between) and Ï†Î¬ÏƒÎ¹Ï‚ (stage), is a stage of mitosis in the eukaryoticcell cycle in which condensed & highly coiled chromosomes, carrying genetic information, align in the middle of the cell before being separated into each of the two daughter cells. Metaphase accounts for approximately 4% of the cell cycle's duration. Preceded by events in prometaphase and followed by anaphase, microtubules formed in prophase have already found and attached themselves to kinetochores in metaphase. The centromeres of the chromosomes convene themselves on the metaphase plate (or equatorial plate), an imaginary line that is equidistant from the two centrosome poles. This even alignment is due to the counterbalance of the pulling powers generated by the opposing kinetochores, analogous to a tug of war between equally strong people. In certain types of cells, chromosomes do not line up at the metaphase plate and instead move back and forth between the poles randomly, only roughly lining up along the middleline. Early events of metaphase can coincide with the later events of prometaphase, as chromosomes with connected kinetochores will start the events of metaphase individually before other chromosomes with unconnected kinetochores that are still lingering in the events of prometaphase.
One of the cell cycle checkpoints occurs during prometaphase and metaphase. Only after all chromosomes have become aligned at the metaphase plate, when every kinetochore is properly attached to a bundle of microtubules, does the cell enter anaphase. It is thought that unattached or improperly attached kinetochores generate a signal to prevent premature progression to anaphase, even if most of the kinetochores have been attached and most of the chromosomes have been aligned. Such a signal creates the mitotic spindle checkpoint. This would be accomplished by regulation of the anaphase-promoting complex, securin, and separase.
Metaphase in the study of cancer and genetics
The analysis of metaphase chromosomes is one of the main tools of cancercytogenetics. Malignant cells from solid tumors or leukemia samples are grown in short term culture and dropped onto microscope slides to generate metaphase preparations. Staining of the slides, often with Giemsa or Quinacrine, produces a pattern of in total up to several hundred bands. Inspection of the stained metaphases allows the determination of numerical and structural changes in the tumor cell genome, for example, losses of chromosomal segments or translocations, which may lead to chimeric oncogenes, such as bcr-abl in chronic myelogenous leukemia. Additionally, normal metaphase spreads are used as hybridization matrix for comparative genomic hybridization (CGH) experiments.
From Yahoo Answers
Answers:metaphase - all chromosomes are double-stranded,and short and thick as they are attached to the mitotic spindle BEFORE anaphase [before being pulled apart] telophase - all of the chromosomes are single-stranded, and are becoming less visible as the nuclear membrane forms around them.
Answers:X, although it will be .5X very soon.
Answers:Homologous chromomsomes are chromosome pairs of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding locis, a specific allele on the chorosome. One is inherited from the fater and one from the mother You are corect that there are no homologouis chromosomes in metaphase 2, becuase in metaphase 2, the chromosomes that *split* are the sister chromatids,...basically they were homologous chromosomes. Also there are 2 homologous chromosomes in metaphase 1
Answers:There are 8,388,608 ways of aligning parents' chromosomes (that's 2^23). This alignment is important in genetic diversity because the random alignment keads to a mixing-up of genetic material. This genetic diversity is important to a species because genetic diversity leads to variation in offspring, which may lead to better adaptation of the species to its environment. See an article I wrote in The American Biology, (65:1), pp 62-4 to see how alignment can affect the offspring's genotype..