Meiosis and mitosis

The processes of meiosis and mitosis involve many motile events, from the separation of the daughter chromosomes to the final act of cell separation at cytokinesis (Wadsworth, 1993). DNA replication itself may be considered as a motile event, because the polymerase complex moves along the linear DNA. One of the most obvious motile events is the separation of the chromosomes along the mitotic spindle at anaphase. Details of the structure and polarity of microtubules in the spindle apparatus in meiosis and mitosis are known through electron and light microscopy, but it is not yet clear whether the chromosomes are pushed, pulled or... 

Diagrams of the phases of meiosis and mitosis are offered m the About Biotech Graphics Gallery, a component of Access Excellence, a national educational programme sponsored by Genentech, Inc. 

Meiosis and mitosis are overall analogous processes involving many of the same proteins. However, some proteins function uniquely in each of these cell division events. Explain the meiosis-specific function of the following (a) Ime2,... 

Luykx, P. 1965a. The structure of the kinetochore in meiosis and mitosis in Urechis eggs. Exp. CeU Res., 39 643-657. 

Levi M, Maro B, Shalgi R. 2010. Fyn kinase is involved in cleavage furrow ingression during meiosis and mitosis. Reproduction 140(6) 827-834. 

Stern, H., Hotta, Y. Facets of intracellular regulation of meiosis and mitosis. In Cell growth and cell division (Harris, R.J.C., ed.). Symp. Int. Soc. Cell Biol., vol. II, p. 57-76. New York Academic Press 1963... 

Repetitive DNA.—The eukaryote genome contains, on average, 30% repetitive sequences. These can be divided into highly repetitive and moderately repetitive classes. Highly repetitive sequences occur at the centromeres of the chromosomes and are generally assumed to be involved in the organization and separation of chromosomes at meiosis and mitosis. 

This involves interference with the processes of mitosis or meiosis and can lead to major changes in chromosome number. 

Prophase. The stage in meiosis or mitosis when chromosomes condense and become visible as refractile bodies. 

Chromatin is the complex combination of DNA, RNA and protein that makes up chromosomes inside the nuclei of eukaryotic cells it is divided between heterochromatin (condensed) and euchromatin (extended) forms. The functions of chromatin are to package DNA into a smaller volume to fit into the cell, to support the DNA to allow mitosis and meiosis, and to serve as a mechanism to control expression and DNA replication. Changes in chromatin strncture are affected by chemical modifications of histone proteins, such as methylation (DNA and proteins) and acetylation (proteins), and by non-histone DNA-binding proteins. Chromatin is easily visualised by staining, hence its name, which literally means coloured, lightened material. 

Since the cofactors are not essential in S. cerevisiae, but the tubulin heterodimer is, it is clear that tubulin in this organism must be able to form heterodimers in the absence of cofactors. One possible explanation for this is that the sequences of the S. cerevisiae tubulins are the most divergent known. Saccharomyces cerevisiae cells contain only relatively simple microtubule arrays that participate in only three well defined and temporally distinct cellular process mitosis, meiosis, and nuclear fusion. Perhaps this reduced selective pressure on their tubulin genes has allowed the evolution of spontaneously dimerizing tubulin in this organism. 

VI. Karyoskeletal Protein-Nucleic Acid Interactions during Interphase and Mitosis/Meiosis Appendix Vendors References... 

MitosiSy and Mitosis Versus Meiosis. Kinetochore structure now becomes a major consideration. Only a brief summary will be given here for a more extensive review see Brinkley and Stubblefield (1970). 

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