Topics: Chromosome, Cell nucleus, DNA Pages: 2 (448 words) Published: November 11, 2013
Our assignment is about how chromosomes separate and how cell division works through microtubules and histones. DNA in the nucleus is loose and not well defined into chromosomes because it is usually tightly coiled, but in the interphase nucleus the chromatin exists in two forms: loosely coiled form called euchromatin and tightly coiled formed called heterochromatin. These two types become more coiled to form the chromosome at the time of cell division. DNA is a bit loosely coiled in the euchromatin its bases are then available for transcription. When it is in the form of heterochromatin, the bases are not accessible for reading by RNA polymerase hence transcription is not possible as majority of genes must be transcribed in the nucleus so the chromosomes must be decondesed to appear in the form of chromatin and that too in form of euchromatin if DNA remained organized in the sense that they would not be accessible for transcription. Before the chromosomes condense the nuclear membrane goes through meiosis which is cell division between and egg and sperm cell that determines the sex of a baby. The sex is found by the sperm which carries a X and Y sex chromosomes. Before the cell divides two sets of chromosomes pair together and swap segments. The second part of our questions was on the bases of chromosomes and how they condense and also how microtubules work to allow cell division. One of the biggest things that stood out in what is required for the chromosomes to condense is the positively charged histone proteins, and the nucleosome formation. Another thing that we found out was how microtubules work to allow cell division. Microtubules help chromosomes move throughout the cell. Also microtubules can add or subtract proteins units to become longer or shorter while continuing to provide the cell with structural support during cell division. All these play major roles in both of the processes that need to take place in order for cell division to take place. Both...
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