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Someone needs to disambiguate this. KirbyMeister 01:36, 10 May 2004 (UTC)
The Idea of crossing over was first proposed by F.A. Janssens. Does anybody know anything more about him? Fawcett5 18:17, 17 January 2006 (UTC)
This article should probably be merged with / redirect to genetic recombination. Gringer 03:02, 7 July 2006 (UTC)
what is its significance can naybody tell me please —The preceding unsigned comment was added by 203.101.182.58 ( talk) 11:28, 27 February 2007 (UTC).
Chromosomal crossover → Homologous recombination — Chromosomal crossover is a naturally occurring type of homologous recombination, but homologous recombination also refers to an artificial technique for introducing different DNA sequences into an organism. "Homologous recombination" has been redirecting to "Chromosomal crossover"; rather than create a different page at "Homologous recombination" (which I started to do), I think "Chromosomal crossover" should change name as it is a significant subset homologous recombination. Madeleine 01:17, 18 April 2007 (UTC)
If you really add more information, I think it will be fine to move the page. As it stands, though, the article is only about the natural version, so I can't really support the move at the moment. Dekimasu よ! 03:41, 23 April 2007 (UTC)
It was requested that this article be renamed but there was no consensus for it be moved. -- Stemonitis 07:09, 23 April 2007 (UTC)
I strongly feel that homologous recombination should be a separate article. Chromosomal crossover, as described in the first sentence of the current article, occurs during prophase of meiosis. However, as mentioned above, chromosomal crossover is only one type of homologous recombination. There are also other types of natural homologous recombination that would not fit into an article on "chromosomal crossover." For example, homologous recombination is necessary for certain types of DNA repair in eukaryotes and prokaryotes. Another example that could not be included in the current article is the homologous recombination that occurs following introduction of homologous DNA into a bacterium by conjugation, transduction, or natural transformation. If you look at textbooks and research articles, all of these examples are said to occur by homologous recombination, not chromosomal crossover. Therefore, a separate article entitled "homologous recombination" is necessary so that these examples can be described somewhere. At the very least, the current article should be renamed "homologous recombination" so that these other examples can be added. NighthawkJ 18:41, 23 May 2007 (UTC)
? isn't this the same as synapsis? 70.246.127.92 20:23, 1 July 2007 (UTC)
I think it is best to give chromosomal crossover its own page, if not for its scientific significance then for its significance as a phenomena of the history of genetics. I do not have citable or certain examples of this, but I suggest that this be looked into. In Mendelian genetics, an allele (consisting of a "homologous pair of chromosomes" per modern genetic theory) was an unchanging factor in the phenotypes of the following generations. However, there is a phenomena, the observation and/or observer of which I do not know, that disproves this principle: the spectrum of dominance (Biology Seventh Edition, Campbell and Reece, 250-60). I am not certain about this, but I believe that chromosomal crossover is a factor of the spectrum of dominance. The spectrum of dominance also was the basis for the earlier theories of inheritance, which held that inheritance was a process of blending. I think it is worth a mention, and it would not be practical to mention it in the page for homologous recombination. Quintus Twig ( talk) 01:19, 14 December 2009 (UTC)
The article does not mention how frequently crossover occurs. Not even extreme values are given. Does it happen once in a million times? All the time? Albmont 13:23, 16 November 2007 (UTC) It happens in every cell undergoing meiosis I. —Preceding unsigned comment added by 76.226.94.200 ( talk) 20:50, 28 November 2007 (UTC)
chromatids ? sister chromatids have identical DNA content, so shuffling between them would produce no change ? —Preceding unsigned comment added by 63.82.71.137 ( talk) 08:44, 30 November 2007 (UTC)
" Interference (genetic) is a phenomenon by which a chromosomal crossover in one interval decreases the probability that additional crossovers will occur nearby. The distribution of crossovers by interference has been postulated to ensure that every pair of homologs receives at least one. The degree of interference and the number of crossovers per meiosis varies between organisms." —Preceding unsigned comment added by 149.169.123.210 ( talk) 20:23, 17 March 2009 (UTC)
This article says the following at the end of its first paragraph: "Chromosomal crossovers also occur in asexual organisms and in somatic cells, since they are important in some forms of DNA repair." I think this is incorrect. The journal article being used as a reference for this statement says: "Recombination in somatic cells is rarely associated with crossovers, and crossovers have the potential to generate genomic rearrangements and large-scale loss of heterozygosity (LOH)." (See: Li X, Heyer WD (2008). "Homologous recombination in DNA repair and DNA damage tolerance". Cell Res. 18 (1): 99–113. doi: 10.1038/cr.2008.1. PMID 18166982.) To my understanding, it is exclusively non-crossover (i.e. gene conversion) products of recombination that result from accurate recombinatorial DNA repair in bacteria and somatic cells in eukaryotes. I've reworked the lead to give what I think is a more accurate description of the subject; any feedback would be appreciated. Emw ( talk) 15:08, 23 October 2009 (UTC)
Several of our biology articles have a somewhat confused mixture of narrowly human and more general biological view points. I think this goes for the section titled Problems in this article, which now reads:
It is true that gene duplication, gene deletion, and gene inversion in general have negative effects for the concerned individuals, and I suppose that therefore unbalanced recombination in a human in general may be considered as a medical problem. However, in the long run, the much rarer instances when the effects are beneficial have had a rather large positive impact on the evolution of certain lines of organisms.
I think both the negative medical effects and the rare but important positive evolutionary effects should be mentioned here. I'll make a try at rewriting the section in such a manner. JoergenB ( talk) 22:40, 3 December 2013 (UTC)
The comment(s) below were originally left at Talk:Chromosomal crossover/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.
Rated "high" as high school/SAT biology content, part of meiosis and genetic recombination. - tameeria 23:27, 18 February 2007 (UTC) |
Last edited at 23:27, 18 February 2007 (UTC). Substituted at 11:43, 29 April 2016 (UTC)
(Warning, haven't read article, this ma be a stupid question already answered) Is it known how crossover works with reference to intron/exon boundaries? Jimw338 ( talk) 13:03, 26 April 2017 (UTC)
The following Wikimedia Commons file used on this page has been nominated for speedy deletion:
You can see the reason for deletion at the file description page linked above. — Community Tech bot ( talk) 12:51, 31 July 2019 (UTC)