NUCLEUS... the cell's largest organelle
         maximum dia 10 um, volume to 40 um3 = about 10% of cell
         found in all eukaryotic cells except erythrocytes & sieve tube cells
Components of the nucleus:
nuclear envelope - a double membrane bound around organelle
nuclear pore complexes regulate nuclear transport in/out
            functional diameter of pores - 10 nm
 chromatin - the stuff of the nucleus:
DNA (5x10-12gm) + histone & Acidic Nuclear Proteins
heterochromatin... a condensed & inactive form of DNA
euchromatin... a less dense & active form of DNA
 nucleolus - site of rDNA genes which make rRNA
nucleoplasm - soluble phase of the nucleus that contains...
             enzymes, RNA's, solutes, chromatin, etc.

EM structure of cell nucleus