Epithelium: Cell Nucleus Flashcards
Cell Nucleus is composed of..
nucleolus chromatin nuclear envelope
The Nuclear Envelope has
Inner membrane Outer membrane
The inner membrane of the Nuclear Envelope is associated with
Nuclear lamina chromatin ribonucleoproteins
The outer membrane of the nuclear envelope is associated with
continuous with membrane of ER ribosomes
Nuclear Pore Complex has what type of structure?
Tripartate Structure (octogonal rings)
The Nuclear Pore Complex is embedded in ..
the Nuclear envelope
The Nuclear Pore complex has what type of proteins
Phe-gly nucleoporins (they control the channels)
How do Phe-gly nucleoporins control the channels?
they are the docking sites for nuclear transport factor cargo proteins
NLS
Nuclear localization signal pro-lys-lys-lys-arg-lys-val
X chromosome inactivation
random can be maternal or paternal in every FEMALE SOMATIC CELL (both x chromosomes in oocytes remain active)
X Chromosome inactivation can be seen in …
Barr Bodies Drumsticks of Neutrophil
How many times is DNA wrapped around histone octomer in chromatin?
1.65 times
What is the linker histone?
H1
what is the basic structural unit of chromatin
nucleosome
What is the histone octomer composed of ?
H2A, H2B, H3,H4
During what phase is chromatin uncondensed?
Interphase (g1,s,g2( Euchromatin
what is transcriptionally active chromatin?
Euchromatin
Euchromatin
transcriptionally active 10%total chromatin site of synthesis of nonribosomal RNA (mRNA & tRNA) precursors
Heterochromatin
condensed transcriptionally inactive 90% of total chromatin
Nucleoplasmic Transport What changes Ran-GTP to Ran-GDP? where?
Ran-GAP in cytoplasm
What changes Ran-GDP to Ran-GTP
RCC1 In nucleus
What does Ran-GBP do?
Ran-gtp binding protein disassociates (NES protein) from Ran-GTP in cytoplasm
what do importins bind to?
alpha importin binds to (NLS Protein) beta importin binds to Ran-GDP
What is a nuclear exportin?
Crm1
Identify from left to right
dense fibrillar component
Granular component
fibrillar center
Nucleostemin
Fibrillarin
Nucleolin
are found in…
Nucleolus
Nuclelous is the site of..
sytnethesis of rRNA
site of assembly of ribosomal subunits
Nucleolus is the product of
chromosome and the nucleolar organizing region (NOR)
The nucleolus has three main compartments
Fibrillar Center
Dense fibrillar Components
Granular Component
Fibrillar Center
RNA Pol I
signal regonition particle
chromatin with repeats of rRNA
Dense Fibrillar Center
Fibrillarin
Nucleolin
ribonucleic prtoeins for rna modification
where nascent rRNA is present and undergoing processing (pre-RNA processing)
surrounds fibrillar centers
Granular Component
Nucleostemin
site of assembly of pre ribosomal subjunits (18S (small) 28S (large))
75% of nuclear mass
Nucleolus
diassociates during mitotis (mitotic prophase)
reappears at beginning of G1
more than one per nucleus sometimes
Nucleolin
forms a coples with RPA which is required for intiation of DNA Synthesis
Fibrillarin & Nucleolin
required for pre-RNA processing (dense fibrillar component)
Nucleolin & Nucleostemin
AKA shuttling proteins (relocalize from nucleolus to nucleoplasm)
in resp to cell stree tnry into S phase (DNA synthesis) can be blocked by shuttling proteins
shuttling proteins bidning and inactivate p53 ( protector of DNA damage)
Nucleostemin
unrelated to ribosomal biogensis
granular componenet
rRNA synthesis occurs in what direction
5’ to 3’
rRNA genes are seen
as repeating units on chromatin separated by nontranscribed spacers
the entire rRNA gene is covered by 100 RNA Pol I molecules
RNA pol I makes
fibrils that represent rRNA Precursor (45S)
45S
rRNA precursor
orientated perpendicular to the chromatin axis
detached from chromatin axis and cleaves into
28S 18S 5.8S rRNAS
What is the large ribosomal subunit?
What precursors create the large ribosomal subunit?
60S
28S+5.8S+ 5S( from OUTSIDE of nucleolus)+ 45 proteins
What is the small ribosomal subunit?
what creates the small ribosomal subunit?
40S
18S+30 proteins
The mRNA precursor is transcribed by
RNA Pol II
the tRNA precursor is transcribed by
RNA pol III
Feulgen Reaction
Specific for DNA
hydrolysis with HCL forms aldehyde groups on deoxyribose (DNA sugar) but no ribose (RNA sugar)
add Schiff reagents
stains DNA with chromatin purple
Effect of Felgen reaction on nucleus and nucleolus
nucleus _stained purple (DNA)
nucleolus _unaffected (RNA)
Autoradiography
H^3 Thymine -DNA
H^3Uridine -RNA
works on living cells
PAS RXN
glycogen in cytoplasm stains pruple
nucleus remains unstained
Basophillia
Toludine Blue (basic dye)
binds to negative phospahge group on DNA & RNA
All stain blue
DNA-chromatin
RNA-nucleolus
ribosomes (ER)
if pretreat with RNAase only identify DNA containing sites
if pretreat with DNAase only identify RNA containing sites
Acidophillia
Eosin (dye)
stains basic proteins
Are basic proteins acidophillic or basophillic
Acidophilic (affinity for acid dyes)
