CAS BI 108 Chapter Notes - Chapter 11.3: Sister Chromatids, Spindle Apparatus, Nuclear Membrane
11 Mar 2014
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Document Summary
Prior to mitosis, eukaryotic dna is packed into very compact chromosomes: chromosome: one or two long, linear double stranded dna molecules bound with many proteins (dna/proteins = chromatin, before. S phase each chromosome contains only one double-stranded dna molecule. After it replicates during s phase there are two double stranded dna molecules: the sister chromatids: sister chromatids are held together by protein complex called cohesin. Cohesin is removed at the end of mitosis. Dna-histone interactions and histone-histone interactions result in nucleosomes. During this phase of the cell cycle, dna is accessible for proteins involved in replication and transcription. However, once a mitotic chromosome is formed, its compactness makes it inaccessible to replication and transcription factors. A single nucleus gives rise to two nuclei that are genetically identical to each other and the parent nucleus. Chromatids separate and move away from each other toward opposite poles. The centrosomes determine the plane of cell division.
