مشروع جينوم الشمبانزي: الفرق بين النسختين
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سطر 21:
البروتينات المتماثلة في الشمبانزي والإنسان تختلف في المتوسط في إثنين من [[حمض أميني|الأحماض الأمينية]] فقط . وتتماثل البروتينات بنسبة 30% في الإنسان وفي الشمبانزي في تتابعها على الكروموسوم بالمقارنة ببروتينات الشمبانزي. وكما ذكرنا أعلاه ، تنشأ معظم التغيرات في الجينات بين الإنسان والشمبانزي أثناء تضاعف الجينات ، حيث 7و2 % من الجينوم تمثل اختلافات نتجت عن عملية تضاعف الجينات
, gene duplications أو مفقودات (إزالات) deletions حدثت أثناء التطور خلال نحو 6 مليون سنة.<ref>{{cite journal| url=http://www.plosgenetics.org/article/info:doi%2F10.1371%2Fjournal.pgen.1000057| title=Analysis of Chimpanzee History Based on Genome Sequence Alignments| editor1-first=Gil| editor1-last=McVean | author=Caswell JL, Mallick S, Richter DJ, Neubauer J, Schirmer C, Gnerre S, Reich D | journal=PLoS Genet. |date = 2008-04-18 |volume=4|page=e1000057| pmid = 18421364| doi=10.1371/journal.pgen.1000057| issue=4| pmc=2278377}}</ref> ، أي منذ أن تفرع الإنسان والشمبانزي من أجدادهم في التطور. التغيرات المماثلة التي حدثت بالنسبة لمجموع البشرية تمثل نحو 5و0 % فقط. <ref>{{cite journal|title=A genome-wide comparison of recent chimpanzee and human segmental duplications|vauthors=Cheng Z, Ventura M |journal=[[Nature (journal)|Nature]]| year=2005 |volume=437 |pages=88–93|doi=10.1038/nature04000 |pmid=16136132|issue=7055 |bibcode=2005Natur.437...88C|display-authors=etal}}</ref>
==الجينات عند التحام الكروموسوم 2==
[[Image:Chromosome2Insert.png|thumb|left|Diagramatic representation of the location of the fusion site of chromosomes 2A and 2B and the genes inserted at this location.]]
تشير نتائج مشروع جينوم الشمبانزي أنه عندما إلتحمت كروموسومات السلف 2A و 2B فأنتجت الكروموسوم 2 لدى اليشر ، أنه لم يحدث فقد أو خلل في الطرفين . 2A و 2B.
At the site of fusion, there are approximately 150,000 base pairs of sequence not found in chimpanzee chromosomes 2A and 2B. Additional linked copies of the PGML/FOXD/CBWD genes exist elsewhere in the human genome, particularly near the p end of [[Chromosome 9 (human)|chromosome 9]]. This suggests that a copy of these genes may have been added to the end of the ancestral 2A or 2B prior to the fusion event. It remains to be determined if these inserted genes confer a selective advantage.
*'''PGML'''. The [[phosphoglucomutase]]-like gene of human chromosome 2. This gene is incomplete and may not produce a functional transcript.<ref>{{cite journal |vauthors=Fan Y, Newman T, Linardopoulou E, Trask BJ |title=Gene content and function of the ancestral chromosome fusion site in human chromosome 2q13-2q14.1 and paralogous regions |journal=Genome Res. |volume=12 |issue=11 |pages=1663–72 |date=November 2002 |pmid=12421752 |pmc=187549 |doi=10.1101/gr.338402 |url=http://www.genome.org/cgi/content/full/12/11/1663}}</ref>
*'''FOXD'''. The [[FOX proteins|forkhead box]] D4-like gene is an example of an intronless gene. The function of this gene is not known, but it may code for a transcription control protein.
*'''CBWD'''. Cobalamin synthetase is a bacterial enzyme that makes [[Cyanocobalamin|vitamin B<sub>12</sub>]]. In the distant past, a common ancestor to mice and apes incorporated a copy of a cobalamin synthetase gene (see: [[Horizontal gene transfer]]). Humans are unusual in that they have several copies of cobalamin synthetase-like genes, including the one on chromosome 2. It remains to be determined what the function of these human cobalamin synthetase-like genes is. If these genes are involved in vitamin B<sub>12</sub> metabolism, this could be relevant to human evolution. A major change in human development is greater post-natal brain growth than is observed in other apes. Vitamin B<sub>12</sub> is important for brain development, and vitamin B<sub>12</sub> deficiency during brain development results in severe neurological defects in human children.
*'''CXYorf1-like protein'''. Several transcripts of unknown function corresponding to this region have been isolated. This region is also present in the closely related chromosome 9p terminal region that contains copies of the PGML/FOXD/CBWD genes.
*Many [[ribosome|ribosomal]] protein L23a [[pseudogene]]s are scattered through the human genome.
==المراجع==
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