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135:" (NORs). The nucleolus in the nucleus remains associated with the NOR of the secondary constriction area. In humans, the number of NORs is equal to the number of nucleoli, which is ten. However, not all secondary constrictions are NORs. The formations of nucleoli takes place around the NOR region. The secondary constriction also contains the
127:, as chromosomes can only bend at the site of primary constriction. Secondary constrictions are useful in identifying a chromosome from a set. There are either 0, 1, 2, 3, or 4 secondary constriction sites in a cell at anaphase. Some parts of these constrictions indicate sites of
194:"Evolutionary aspects of the ZZ/ZW sex chromosome system in the Characidae fish, genus Triportheus. A monophyletic state and NOR location on the W chromosome" - Heredity
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204:"Molecular characterization of the secondary constriction region (qh) of human chromosome 9 with pericentric inversion" - Journal of Cell Science
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189:"Physical locations of 5S and 18S-25S rDNA in Asian and American diploid Hordeum species with the I genome" - Heredity
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199:"Evolutionary implications of permanent odd polyploidy in the stable sexual, pentaploid of Rosa canina L" - Heredity
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level. The top of chromosomes 13, 14, 15, 21, & 22 are satellites, with a
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167:(SAT chromosome). DNA in a secondary constriction which forms rRNA is called
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are the constricted or the narrow region found at any point of the
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184:"Karyomorphological Studies of Species in Taxodiaceae " - METLA
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174:NORs occur in SAT chromosomes (13,14,15,21,22).
49:but its sources remain unclear because it lacks
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80:Learn how and when to remove this message
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133:nucleolar organizing regions
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131:formation and are called "
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113:Secondary constrictions
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16:Further information:
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143:synthesis (
62:introducing
266:Categories
219:cell cycle
121:centromere
117:chromosome
102:centromere
96:Schematic
70:March 2019
149:5.8S rRNA
129:nucleolus
98:karyogram
18:Karyotype
153:28S rRNA
145:18S rRNA
125:anaphase
272:Mitosis
157:5S rRNA
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217:This
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