Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
20 Cards in this Set
- Front
- Back
|
What surrounds the nuclear envelope on its cytoplasmic side? (2x)
|
Loosely arranged mesh of intermediate filaments: vimentin.
Ribosomes which synthesize proteins that enter perinuclear cisterna |
|
|
Thickness and composition of nuclear envelope (inner + outer + perinuclear cisterna)
|
Inner: 6 nm
Outer 6 nm Inner membrane separated by perinuclear cisterna (space) from outer membrane. Perinuclear cisterna = 20-40 nm wide |
|
|
What is the nuclear lamina?
|
Faces internal nuclear material.
Supported by nuclear lamina (network composed of lamins A, B, and C) |
|
|
Function and composition of lamin proteins (A, B, and C; 2x funx)
|
1. Organize nuclear envelope and perinuclear chromatin
2. Responsible for disassembly and reasembly of the nuclear envelope (phosphorlyation of lamins --> diassembly; dephosphorlyation of lamins --> assembly) |
|
|
What is the NPC (nuclear protein complex)?
|
Composed of 100 proteins surrounding nuclear pore complex. Nucleoplasmic side of pore exhibits a nuclear basket, cytoplasmic side has fibers into cytoplasm.
|
|
|
Mechanism of NPC (type of transport)
|
Transporter protein in middle and responsible for transporting proteins into and out of nucleus via receptor mediated transport.
|
|
|
Cytoplasmic ring (part of NPC)
|
Composed of eight subunits around cytoplasmic margin of nuclear pore. Each cytoplasmic filament is a Ran-binding protein extending into cytoplasm.
|
|
|
Nucleoplasmic ring (part of NPC)
|
Around nucleoplasmic margin of nuclear pore and composed of eight subunits.
Nuclear basket extendings into nucleoplasm. |
|
|
What is composition and function of Nuclear Basket?
|
Nuclear basket is a component of the NPC and extends into the nucleoplasm. Distal end of nuclear basket is the distal ring.
Function: RNA transport |
|
|
What is the luminal ring?
|
Luminal ring is 8 transmembrane proteins which are b/t cytoplasmic ring and nuclear ring.
Proteins extend into perinuclear cisterna. |
|
|
What is the function of NPC (2x)?
|
1. 9-11 nm opening in NPC allows simple diffusion
2. Most proteins pass via receptor-mediated transport with requisite nuclear localization signals (NLS) |
|
|
What are the transport mechanisms in and out of the nucleus? (2x)
|
1. Importins and exportins regulated by Ran
2. Nucleoporins which shuttle back and forth via nucleocytoplasmic shuttling (NS) signals. |
|
|
What are nucleoloar organizer regions (NOR)?
|
Portions of chromosomes (13, 14, 15, 21, 22) where rRNA genes are located
Regions reconstitute nucleolus during G1 phase of cell cycle |
|
|
What are the regions of the nucleolus? (4x)
|
1. Fibrillar centers: inactive DNA where DNA not being transcribed (NORs are located here)
2. Pars fibrosa: surround fbrillar centers and have transcriptionally active DNA and rRNA being transcribed 3. Pars Granulosa: maturing ribosomal precursor particles 4. Nucleolar matrix: fiber network which organizes nucleolus |
|
|
What are the nuclear particles and function? (4x)
|
1. Interchromatin granules: clusters of irreg. distributed particles that contain RNP and various enzymes
2. Perichromatin granules: located at periphery of heterochromatin and exhibit substructure of 3-nm packed fibrils May represent messenger RNPs (mRNPs) 3. hnRNP particles: complexes of precursor mRNA and proteins involved in pre-mRNA processing 4. Small nuclear RNPs (snRNPs) complexes of proteins and small RNAs involved in splicing/cleavage rxns. |
|
|
What are the two types of chromatin and their funx?
|
Heterochromatin: transcrip inactive, appears darker, Barr Bodies, has additional histone (H1)
Euchromatin: lighter, transcriptionally active |
|
|
What is terminal sequent in tRNA?
|
5` CCA 3`
Where amino acid attaches. |
|
|
How are ribosomes formed? (3 steps)
|
1. rRNA synthesis processes a 45S precursor rRNA to 28S, 18S, and 5.8S rRNA.
2. RNP (28S + 5.8 S rRNA) combines with 5S (synthesized outside nucleolus) to form large subunit. 3. Small subunit is 18S rRNA |
|
|
What are the cyclin/CDK checkpoints? Function, location (4x)
|
1. Cyclin D + CDK enable cell to enter and advance through S phase
2. Cyclin E + CDK enable cell to enter and advance through S phase 3. Cyclin A binds to CDKs; cell can leave S phase + produce cyclin B 4. Cyclin B binds CDK, enable cell to leave G2 and enter M phaes |
|
|
Prometaphase
|
Beings when nuclear envelope disappears completely; kinetochores complete development and attach to spindle microtubules; spindle microtubules that do not attach to kinetochores are polar microtubules
|
