<P> In eukaryotes , nuclear chromosomes are packaged by proteins into a condensed structure called chromatin . This allows the very long DNA molecules to fit into the cell nucleus . The structure of chromosomes and chromatin varies through the cell cycle . Chromosomes are even more condensed than chromatin and are an essential unit for cellular division . Chromosomes must be replicated , divided , and passed successfully to their daughter cells so as to ensure the genetic diversity and survival of their progeny . Chromosomes may exist as either duplicated or unduplicated . Unduplicated chromosomes are single double helixes , whereas duplicated chromosomes contain two identical copies ( called chromatids or sister chromatids ) joined by a centromere . </P>
<P> In eukaryotes , nuclear chromosomes are packaged by proteins into a condensed structure called chromatin . This allows the very long DNA molecules to fit into the cell nucleus . The structure of chromosomes and chromatin varies through the cell cycle . Chromosomes are even more condensed than chromatin and are an essential unit for cellular division . Chromosomes must be replicated , divided , and passed successfully to their daughter cells so as to ensure the genetic diversity and survival of their progeny . Chromosomes may exist as either duplicated or unduplicated . Unduplicated chromosomes are single double helixes , whereas duplicated chromosomes contain two identical copies ( called chromatids or sister chromatids ) joined by a centromere . </P>
where are chromosomes found in a plant cell
where are chromosomes found in a plant cell
cell nucleus
cell nucleus