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Nuclear and Cell Div
Terms for Nuclear and Cell Division for NW 04-350
| Term | Definition |
|---|---|
| chromatin | the combination of DNA and protein. microscopists first used this term to describe the disorganized material in the nucleus before prophase, where individual chromosomes were not visible |
| binary fission | the process of cell division after DNA replication in a prokaryotic cell |
| homologous pair | in diploid organisms, chromosomes exist in pairs that carry the same genes, but not necessarily the same alleles |
| allele | a version of a gene, mutations create different alleles which may code for different versions (functional or not) proteins |
| diploid | a cell carrying two copies of each chromosomal set, carrying two members of a homologous pair |
| polyploid | a cell carrying additional copies of all homologous sets beyond two, triploid, tetraploid, pentraploid, hexaploid etc. |
| monoploid | a cell carrying one copy of each chromosome |
| haploid | a cell carrying half the number of total chromosomes relative to its original state. because most of the organisms that we are concerned with a diploid, their haploid daughter cells would carry one copy of each chromosome and be monoploid |
| centromere | region on the chromosome where a consensus sequence is found that binds with proteins that allow two sister chromatids formed after replication to remain connected. the spindle fibers also attach here |
| kinetochore | proteins that bind to the centromere, connecting chromatids together. also serves as the motor that allows chromosomes to move over the spindle fibers |
| cell cycle | the series of events in the life span of an individual cell, from the cells origin after cell division is completed until the cell divides again |
| interphase | the dominant stage in the life cycle of the cell, dedicated to cell growth, development and function |
| M phase | mitotic phase/meiotic phase depending on cell type. when the events of nuclear division occur to be followed by cytokinesis |
| nuclear division | events of prophase through telophase that begin with a cell with one nucleus and concludes with two nuclei at the end |
| cytokinesis | division of the cell, division of the cytoplasm. events that partition all of the organelles and one of the two nuclei in distinct cells. occurs after nuclear division is complete |
| G1 | gap 1 or growth 1. substage of interphase where the cell grows, organelles accumulate, and metabolism of the cell occurs |
| S | synthesis. stage of interphase when DNA replication occurs |
| G2 | gap 2 or growth 2. substage of interphase when all the events of G1 take place but specific proteins needed for nuclear and cell division are synthesized |
| sister chromatids | the two halves of a replicated chromosome, still connected at the centromere. not the same thing as a homologous pair. sister chromatids are pulled apart from each other in anaphase of mitosis and anaphase II of meiosis |
| prophase | first stage of nuclear division, typified by compaction of DNA, breakdown of the nuclear envelope, migration of the centrosomes and formation of the spindle |
| condensins | proteins present during nuclear division that allow maximal compaction of replicated chromosomes to form the classic X shaped structure |
| spindle | cytoskeletal structure made of microtubules (tubulin) that organizes the chromosomes during nuclear division and serves as the highway over which they move |
| centrosome | protein structure around which the spindle will anchor itself. there will be one centrosome at each end (pole) of the cell. many centrosomes contain a centriole (not as common in plants) |
| prometaphase | intermediate stage typified by when the nuclear membrane is broken down enough to allow the spindle to penetrate the region and attach to the centromeres of replicated chromosomes |
| metaphase | substage of nuclear division when replicated chromosomes line up in the middle of the cell on the metaphase plate |
| anaphase | substage of nuclear division when genetic material is moving in opposite directions using the spindle as a highway. may be separation of sister chromatids, or homologous chromosomes depending upon if it is mitosis or anaphase I and II of meiosis |
| telophase | substage of nuclear division where new nuclear envelopes form and the chromosomes begin to relax due to release of condensins |
| meiosis I | first cycle of nuclear division (pro thru telo) leading to the first meiotic division (cytokinesis) |
| meiosis II | second cycle of nuclear division (pro thru telo) leading to the second meiotic division (cytokinesis |
| synapsis | event unique to prophase I when homologous replicated chromosomes merge together into a single structure. this is when recombination (crossing over) will occur |
| tetrad | a structure formed due to the synapsis of two replicated chromosomes, composed of four total chromatids |
| interkinesis | rest stage between the first meiotic division and the beginning of prophase II. DNA replication does not occur during interkinesis |
| segregation | the process of separating genetic material into new nuclei. occurs during anaphase |
| genetic variation | generation of cells that are genetically different than their parents. may be the result of recombination, independent assortment, or unique fertilization during sexual reproduction |
Created by:
jthorns
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