Exam 1 Flashcards
membranes made of:
head:
tail:
phospholipid bilayer
hydrophilic
hydrophobic
hydrophobic + hydrophilic =
amphipathic
components of nuclear envelope (NE) structure:
outer membrane, intermembrane space, inner membrane, nuclear pore complexes (NPC), nuclear lamina
NE outer membrane:
continuous with ER, membrane proteins bind to cytoskeleton
NE inner membrane:
integral proteins that bind nuclear lamina
NE nuclear pore complex (NPC):
connect inner and outer membrane, traffic molecules that can’t diffuse, made of nucleoporin proteins (NUPs)
NE nuclear lamina:
connected to inner membrane, cytoskeleton, and chromatin; made up of lamins
lamin assembly:
1) two monomers dimerize
2) then tetramerize
3) then join end to end
proteins that connect nuclear lamina to inner membrane
LBR and emerin
proteins that connect nuclear lamina to cytoskeleton
LINC complex
diseases arising from heritable mutations in lamins or other envelope proteins
laminopathies
laminopathy hypotheses:
mechanical stress hypothesis and gene expression hypothesis
laminopathy mechanical stress hypothesis:
weakened cytoskeletal interactions
laminopathy gene expression hypothesis:
cell-type specific chromatin localization
nuclear pore complex (NPC):
passive diffusion and selective transport; eightfold symmetric complex
components of nuclear pore complex (NPC):
cytoplasmic filament, cytoplasmic ring, central channel/inner ring, FG-NUPs, nuclear ring, nuclear basket
FG-NUPs:
phenylalanine-glycine (FG) repeats in NPC inner ring that are unfolded to facilitate active cargo transport
selective transport of mRNAs direction and energy used:
unidirectional;
ATP
selective transport of mRNAs direction:
unidirectional
selective transport of proteins direction and energy used:
bidirectional;
GTP
selective transport of proteins: nuclear transport receptor (NTR) = ___;
recognize ___
karyopherin (importin/exportin);
amino acid signal sequences (NLS/NES)
protein import through NPC:
protein export through NPC:
mRNA export through NPC:
mRNP (messenger ribonuceloprotein) =
mRNA + proteins (including exporter complex)
NF-kB
transcription regulator, activates genes regulating cell survival when imported into nucleus
IkB
inhibitor of kB
regulation of nuclear import of transcription factors (NF-kB):
chromosome territories:
non-random distribution, spaced out, anchored at centromeres and telomeres to NE
fluorescence in situ hybridization (FISH):
helps visualize chromosomes, DNA probes with fluorescent molecule hybridize to sequences
chromosome conformation capture (3C):
elucidates chromosome architecture; freeze interactions between protein-linked sequences, ligate interacting sequences together end-to-end, NextGen DNA sequencing
euchromatin
active chromatin, associates with nuclear interior or NPC
heterochromatin
inactive chromatin, associates with nuclear envelope lamin associated domains (LADs) and nucleolus associated domains (NADs)
types of nuclear factories:
replication factories and transcription factories
nuclear bodies:
discrete (no membrane) organelles in nucleus; include nucleolus, polycomb bodies, and cajal bodies/nuclear speckles
nucleolus
site of rRNA (4 types) production and ribosome assembly