Changes

The chromosomal DNA molecule contains three specific [[nucleotide]] sequences which are required for replication: a DNA replication origin; the [[centromere]] to attach the DNA to the mitotic spindle.; a [[telomere]] located at each end of the linear chromosome. <ref>http://ghr.nlm.nih.gov/ghr/chromosomes</ref>  

The chromosomal DNA molecule contains three specific [[nucleotide]] sequences which are required for replication: a DNA replication origin; the [[centromere]] to attach the DNA to the mitotic spindle.; a [[telomere]] located at each end of the linear chromosome. <ref>http://ghr.nlm.nih.gov/ghr/chromosomes</ref>  

==Number of Chromosomes==

==Number of Chromosomes==

Chromosomes are further identified by banding patterns created by specialized staining procedures to produce G bands, R bands, C bands, etc. The choice of staining procedure depends upon the information that is desired. Most commonly, chromosomes are stained with trypsin-Giemsa to produce the G-banded pattern. The banding pattern is determined by the degree of chromatin condensation and the specific DNA-protein present at the different sites on the chromosome. These banding patterns are distinct and consistent for each chromosome. Thus, one can reliably identify the chromosome pairs (e.g., although of the same size and shape, the six acrocentric chromosomes in the D group can be differentiated into pairs 13, 14 or 15 based upon banding patterns). The bands are individually numbered (e.g., 11q23 refers to band #23 on the long arm q of chromosome #11). :<ref>http://www.vivo.colostate.edu/hbooks/genetics/medgen/chromo/cytotech.html</ref>

Chromosomes are further identified by banding patterns created by specialized staining procedures to produce G bands, R bands, C bands, etc. The choice of staining procedure depends upon the information that is desired. Most commonly, chromosomes are stained with trypsin-Giemsa to produce the G-banded pattern. The banding pattern is determined by the degree of chromatin condensation and the specific DNA-protein present at the different sites on the chromosome. These banding patterns are distinct and consistent for each chromosome. Thus, one can reliably identify the chromosome pairs (e.g., although of the same size and shape, the six acrocentric chromosomes in the D group can be differentiated into pairs 13, 14 or 15 based upon banding patterns). The bands are individually numbered (e.g., 11q23 refers to band #23 on the long arm q of chromosome #11). :<ref>http://www.vivo.colostate.edu/hbooks/genetics/medgen/chromo/cytotech.html</ref>