BI203 Lecture 16: The Nucleus - Structure of the Nuclear Envelope Flashcards
The ____ is the main feature that distinguishes eukaryotic from prokaryotic cells.
nucleus
The nucleus houses the ____, and thus is the repository of genetic information and the cell’s control center.
Separation of the ____ from the site of mRNA translation plays a central role in eukaryotic gene expression.
genome
The nuclear envelope is composed of ____ phospholipid bilayers and a lumen called the ____ ____.
two, perinuclear space
The perinuclear space is continuous with the ____ of the ER.
lumen
The ____ ____ separates the nuclear contents from the cytoplasm.
nuclear envelope
The nuclear envelope consists of:
- ____ nuclear membranes
- An underlying ____ ____
- Nuclear ____ ____
two, nuclear lamina, pore complexes
The nuclear membrane controls traffic of ____ and ____ through nuclear pore complexes, and plays a critical role in regulating gene expression.
proteins, RNAs
Nuclear membrane:
The outer membrane is continuous with the ____ ____.
The space between inner and outer membranes is directly connected with the ____ of the ER.
The inner membrane has integral proteins, including ones that bind the ____ ____.
endoplasmic reticulum (ER), lumen, nuclear lamina
____ = Primary component of the structure of the nuclear membrane.
lamins
____ ____: A fibrous mesh that provides structural support. Consists of fibrous proteins (____) and other proteins.
nuclear lamina, lamins
Lamins are a class of intermediate filament proteins that associate to form higher order structures:
Two lamins interact to form a ____: the α-helical regions wind around each other to form a ____.
The lamin dimers associate with each other to form the ____.
dimer, coiled-coil, lamina
Mutations in ____ genes cause several inherited tissue-specific diseases.
The bases of the pathologies in each of these diseases is still unclear.
lamin
Nuclear lamina is anchored to the inner nuclear membrane via ____ ____ and ____ ____ (____).
protein-protein interactions, lipid additions (prenylation)
Nuclear lamins bind chromatin indirectly via interactions between lamin-associated proteins & histones ____ & ____.
H2A, H2B
Lamins bind to inner membrane proteins such as ____ and ____ ____ ____ (LBR).
They are connected to the cytoskeleton by ____ protein complexes.
Lamins also bind to chromatin.
emerin, lamin B receptor (LBR), LINC
____ ____ ____ - Sole channels for all transport into and out of the nucleus.
Nuclear pore complexes
Nuclear membranes are phospholipid bilayers permeable only to ____ ____ molecules.
____ ____ ____ are the only channels for polar molecules, ions, and macromolecules.
small, nonpolar, nuclear pore complexes
Nuclear pore complexes are composed of
~30 proteins called ____.
nucleoporins
Nuclear transport:
____ synthesized in the nucleus must be exported to the cytoplasm for protein synthesis.
____ needed for nuclear functions must be imported from synthesis sites in the cytoplasm.
RNAs, Proteins
Electron microscopy shows pore complexes have ____ subunits organized around a large central ____.
Eight ____ are connected to rings at the nuclear and cytoplasmic surfaces.
The spoke-ring assembly surrounds a central channel.
Protein filaments extend from the rings, forming a ____ structure on the nuclear side.
eight, channel, spokes, basket
Molecules pass through nuclear pore complexes by ____ mechanisms:
____ ____ — Small molecules pass freely in either direction.
Proteins and RNAs are ____ ____ - requires energy.
two, passive diffusion, selectively transported
