File:Nucleus structure cartoon 01.jpg

Nucleus Structure

This cartoon shows the general structure of the nucleus of any cell when it is carrying out its normal function (transcriptionally active) and not dividing (mitosis).

Chromosomes are unravelled and spread throughout the nucleus in "chromosome territories". During cell division DNA is folded and compacted into chromosomes and the entire nucleus is disassembled and then reassembled in the 2 daughter cells.

• nuclear envelope - the double membrane surrounding the entire nucleus.
• nuclear pore - the specialised channel passing through the nuclear envelope that allows passage of molecules into and out of the nucleus.
• nuclear lamina - the specialised cytoskeleton that lies under the envelope that gives the nucleus its shape and attaches to unfold DNA.
• chromosome territory - the 3 dimensional space occupied by the DNA of a single unfolded chromosome within the nucleus.
• interchromatin compartment - small spaces not occupied by DNA. These spaces are sites for RNA processing after transcription from DNA.
• nucleolus - a functional compartment within the nucleus formed from DNA from several chromosomes. This region contains ribosomal RNA (rRNA) genes and is continuously nuclear transcriptionally active.
• nuclear speckle - interchromatin granule clusters thought to be sites of storage of messenger RNA (mRNA) splicing factors.
• Cajal body - one of several sites where small nuclear ribonucleoproteins (snRNPs) and small nucleolar RNAs (snoRNPs) are modified.
• PML body - (ProMyelocytic Leukaemia body) suggested to have several different functions.

Links: Image - fibroblast nucleus | Genetics | Mitosis

Reference

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Copyright

Order Details Licensee: Mark A Hill License Date: Mar 28, 2008 License Number: 1917460893134 Publication: Nature Reviews Genetics Title: Dynamic genome architecture in the nuclear space: regulation of gene expression in three dimensions Type Of Use: Web Site