Editing Cell division (section)

=== Prophase ===
[[Prophase]] is the first stage of division. The nuclear envelope begins to be broken down in this stage, long strands of chromatin condense to form shorter more visible strands called chromosomes, the nucleolus disappears, and the mitotic spindle begins to assemble from the two centrosomes.<ref>{{cite journal | vauthors = Schermelleh L, Carlton PM, Haase S, Shao L, Winoto L, Kner P, Burke B, Cardoso MC, Agard DA, Gustafsson MG, Leonhardt H, Sedat JW | display-authors = 6 | title = Subdiffraction multicolor imaging of the nuclear periphery with 3D structured illumination microscopy | journal = Science | volume = 320 | issue = 5881 | pages = 1332–6 | date = June 2008 | pmid = 18535242 | pmc = 2916659 | doi = 10.1126/science.1156947 | bibcode = 2008Sci...320.1332S }}</ref> Microtubules associated with the alignment and separation of chromosomes are referred to as the spindle and spindle fibers. [[Chromosomes]] will also be visible under a microscope and will be connected at the centromere. During this condensation and alignment period in meiosis, the homologous chromosomes undergo a break in their double-stranded DNA at the same locations, followed by a recombination of the now fragmented parental DNA strands into non-parental combinations, known as crossing over.<ref>{{Cite journal|last1=Lewontin|first1=Richard C.|last2=Miller|first2=Jeffrey H.|last3=Gelbart|first3=William M.|last4=Griffiths|first4=Anthony J.F. | name-list-style = vanc |date=1999|title=The Mechanism of Crossing-Over|url=https://www.ncbi.nlm.nih.gov/books/NBK21271/ |journal=Modern Genetic Analysis }}</ref> This process is evidenced to be caused in a large part by the highly conserved [[Spo11]] protein through a mechanism similar to that seen with [[topoisomerase]] in DNA replication and transcription.<ref>{{cite book|last=Keeney|first=Scott|name-list-style=vanc|title=Mechanism and control of meiotic recombination initiation|volume=52|date=2001|pages=[https://archive.org/details/currenttopicsind0000scha_v7u9/page/1 1–53]|publisher=Elsevier|isbn=9780121531522|doi=10.1016/s0070-2153(01)52008-6|pmid=11529427|series=Current Topics in Developmental Biology|url=https://archive.org/details/currenttopicsind0000scha_v7u9/page/1}}</ref>