The Nucleus

1) Organize chromatin (inactive heterochromatin)2) Maintain shape of the nucleus3) Phosphorylated early prophase, dephosphorylated in telophase

1) Outer membrane --> connected to ER, ribosomes2) Perinuclear space3) Inner membrane --> connected by nuclear pores, no ribosomes

1) Fibrous matrix inside membrane of all nuclei -binds to some chromatin regions2)Responsible for shape of nucleus3) Lamina proteins (lamins) phosphorylated/dephosphorylated during mitosis --> breakdown of nuclear envelope

1) nucleoporins - 8 pairs of subunits2) 3-4,000 pores per human nucleus3) Allows free passage of molecules smaller than 9 nm

A cell's synthetic activity.

1) Pars Amorpha (Pale Staining Region)2) Pars Fibrosa (Fibrillar Component)3) Pars Granulosa (Granular Component)

-Contains DNA of nuclear organizer region-Includes repeated sequences of rRNA encoding genes-200 genes on 5 chromosomes

-Composed of elongating fibers of elongating rRNA (5nm diameter)

-Composed of forming ribosomal precursors (15 nm)-rRNA complexes with 70+ different proteins to form ribosomal subunits-The subunits are transported out of the nucleus before activation.

1) Heterochromatin - tightly coiled and transcriptionally inactive, dark-staining2) Euchromatin - light-staining, uncoiled, transcriptionally active.

1-2% of human genome codes for RNA.-most is "mobile genetic elements"/junk DNA

Highly positively charged to attract DNA (likely would have lots of Lysine, Arginine, Histidine)-There are 5 types of histones

1) Nucleosome --> 8 histones w/ wound DNA2) Chromatin Fiber --> 30 nm diameter, adjacent nucleosomes3) Looped domains --> ~400 nm long, scaffolding4) Condensed chromosome --> looped domains form tight helix

7-10% transcribed1-2% gets into cytoplasm

1) Zinc finger: recognizes specific sequences2) Leucine zipper: allows TFs to dimerize