Changes

==Physical Characteristics of Chromosomes==

==Physical Characteristics of Chromosomes==

Most chromosomes have the rough shape of an X. Each chromosome has a constriction point called the [[centromere]], which divides the chromosome into two sections, or “arms.” The short arm of the chromosome is labeled the “p arm.” The long arm of the chromosome is labeled the “q arm.” The location of the centromere on each chromosome gives the chromosome its characteristic shape, and can be used to help describe the location of specific genes.<ref>http://www.rothamsted.ac.uk/notebook/courses/guide/chromo.htm</ref>

Most chromosomes have the rough shape of an I when they condense prior to replication and are as bits of long invisible string when unwound. The familiar X shape actually refers to 2 identical chromosomes referred to as sister chromatids. Each chromosome has a constriction point called the [[centromere]], which divides the chromosome into two sections, or “arms.” The short arm of the chromosome is labeled the “p arm” for "petite". The long arm of the chromosome is labeled the “q arm” for "not petite". The location of the centromere on each chromosome gives the chromosome its characteristic shape, and can be used to help describe the location of specific genes.<ref>http://www.rothamsted.ac.uk/notebook/courses/guide/chromo.htm</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>

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>