BI203 Lecture 16: The Nucleus - Structure of the Nuclear Envelope

Question 1

The ____ is the main feature that distinguishes eukaryotic from prokaryotic cells.

Answer 1

nucleus

Question 2

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.

Answer 2

genome

Question 3

The nuclear envelope is composed of ____ phospholipid bilayers and a lumen called the ____ ____.

Answer 3

two, perinuclear space

Question 4

The perinuclear space is continuous with the ____ of the ER.

Answer 4

lumen

Question 5

The ____ ____ separates the nuclear contents from the cytoplasm.

Answer 5

nuclear envelope

Question 6

The nuclear envelope consists of:

• ____ nuclear membranes
• An underlying ____ ____
• Nuclear ____ ____

Answer 6

two, nuclear lamina, pore complexes

Question 7

The nuclear membrane controls traffic of ____ and ____ through nuclear pore complexes, and plays a critical role in regulating gene expression.

Answer 7

proteins, RNAs

Question 8

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 ____ ____.

Answer 8

endoplasmic reticulum (ER), lumen, nuclear lamina

Question 9

____ = Primary component of the structure of the nuclear membrane.

Answer 9

lamins

Question 10

____ ____: A fibrous mesh that provides structural support. Consists of fibrous proteins (____) and other proteins.

Answer 10

nuclear lamina, lamins

Question 11

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 ____.

Answer 11

dimer, coiled-coil, lamina

Question 12

Mutations in ____ genes cause several inherited tissue-specific diseases.
The bases of the pathologies in each of these diseases is still unclear.

Answer 12

lamin

Question 13

Nuclear lamina is anchored to the inner nuclear membrane via ____ ____ and ____ ____ (____).

Answer 13

protein-protein interactions, lipid additions (prenylation)

Question 14

Nuclear lamins bind chromatin indirectly via interactions between lamin-associated proteins & histones ____ & ____.

Answer 14

H2A, H2B

Question 15

Lamins bind to inner membrane proteins such as ____ and ____ ____ ____ (LBR).
They are connected to the cytoskeleton by ____ protein complexes.
Lamins also bind to chromatin.

Answer 15

emerin, lamin B receptor (LBR), LINC

Question 16

____ ____ ____ - Sole channels for all transport into and out of the nucleus.

Answer 16

Nuclear pore complexes

Question 17

Nuclear membranes are phospholipid bilayers permeable only to ____ ____ molecules.
____ ____ ____ are the only channels for polar molecules, ions, and macromolecules.

Answer 17

small, nonpolar, nuclear pore complexes

Question 18

Nuclear pore complexes are composed of

~30 proteins called ____.

Answer 18

nucleoporins

Question 19

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.

Answer 19

RNAs, Proteins

Question 20

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.

Answer 20

eight, channel, spokes, basket

Question 21

Molecules pass through nuclear pore complexes by ____ mechanisms:
____ ____ — Small molecules pass freely in either direction.
Proteins and RNAs are ____ ____ - requires energy.

Answer 21

two, passive diffusion, selectively transported