6. Nucleus Flashcards
What structure has a concentration of RNA & protein; site of production + maturation of ribosomal subunits
Nucleolus
What is transcribed in the center of the nucleolus?
rRNA
What is pars fibrosa?
newly transcribed rRNA
What is pars granulose?
fully matured ribosomal subunits
What is a transmembrane protein imbedded in nuclear membrane with proteins extending into cytoplasm and nucleus and central plug regulates entry?
nuclear pore
Anything ______ daltons can go through pore with plug in by simple diffusion.
20-500
Can nucleotides diffuse through nuclear pore with plug in?
yes
If nucleotides are covalently linked they can they pass through nuclear pore with plug in?
no, ATP is required to move plug
Can ATP (330 daltons) diffuse through pore with plug in?
Yes
The transport of proteins is a selective process and requires the oplypeptides to have a certain amino acid sequence _____. Which has a localized predominance of ____ and _____ residues.
- NLS (Nuclear Localization Sequence)
- Arginine and lysine Residues
Transport of the protein though the nuclear pore requires interaction between the nuclear localization sequence of a protein and _______.
dimer of Importin (chaperone protein)
DNA+Protein=?
Chromatin
what is “active” DNA- being transcribed; less protein and less electron dense?
Euchromatin
What is “least active” DNA; bound by many proteins and more electron dense?
heterochomatin
What is the region where sister chromatids come in contact?
Centromere
