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Nucleus What is the main function of the nuclear envelope in eukaryotic cells? a) Regulating cell division b) Controlling gene expression c) Maintaining cell shape d) Facilitating protein synthesis Answer: b) Controlling gene expression Which part of the nuclear envelope is continuous with the endoplasmic reticulum? a) Inner nuclear membrane b) Outer nuclear membrane c) Nuclear lamina d) Nuclear pore complexes Answer: b) Outer nuclear membrane What is the space between the inner and outer nuclear membranes connected with? a) Golgi apparatus b) Mitochondria c) Endoplasmic reticulum lumen d) Ribosomes Answer: c) Endoplasmic reticulum lumen Which filamentous proteins make up the nuclear lamina? a) Actin b) Microtubules c) Lamins d) Tubulin Answer: c) Lamins How do lamins associate to form the nuclear lamina? a) Through disulfide bonds b) Through hydrogen bonds c) By forming tetramers d) By coiled coil interactions Answer: d) By coiled coil interactions What is the function of LINC protein complexes in relation to the nuclear lamina? a) They facilitate nuclear pore complex assembly.

b) They link the nuclear lamina to the cytoskeleton. c) They regulate gene expression. d) They transport small molecules. Answer: b) They link the nuclear lamina to the cytoskeleton. What is the primary function of nuclear pore complexes in eukaryotic cells? a) Synthesizing proteins b) Facilitating cell division c) Regulating gene expression d) Mediating molecular transport between the nucleus and cytoplasm Answer: d) Mediating molecular transport between the nucleus and cytoplasm Which mechanism allows small molecules, ions, and proteins smaller than 40 kd to pass through nuclear pore complexes? a) Passive diffusion b) Active transport c) Endocytosis d) Exocytosis Answer: a) Passive diffusion For larger proteins and RNAs, which mechanism of transport occurs through nuclear pore complexes? a) Endocytosis b) Selective transport c) Facilitated diffusion d) Osmosis Answer: b) Selective transport What directs the selective transport of larger proteins and RNAs through nuclear pore complexes? a) Specific directional signals b) Passive diffusion c) Hydrogen bonding d) Ribosomal RNA Answer: a) Specific directional signals What is the primary function of nuclear pore complexes in eukaryotic cells? a) Protein synthesis b) Facilitating cell division

c) Regulating gene expression d) Mediating molecular transport between the nucleus and cytoplasm How many different pore proteins, known as nucleoporins (NUPs), make up a nuclear pore complex? a) Approximately 10 b) Roughly 20 c) About 30 d) Over 50 Answer : c) about 30 Which part of the nuclear pore complex forms a basket-like structure on the nuclear side? a) Protein filaments b) Central channel c) Spokes d) Rings Answer: a) protein filament What type of proteins line the central channel of the nuclear pore complex, acting as a barrier to pore permeability? a) Actin filaments b) FG-NUPs c) Lamins d) Ribosomal proteins Answer: b) FG-NUps (central channels is lined by phenylalanine and glycine rich protein called FG-NUPs) How do millions of macromolecules selectively pass between the nucleus and cytoplasm every minute? a) Through passive diffusion b) Via the action of histones c) With the help of importin and exportin transporter proteins d) By osmotic pressure Answer: c) With the help of importin and exportin transporter proteins Which energy source is required for active importin/exportin nuclear protein transport? a) ATP b) GTP c) DNA d) RNA Answer: b) GTP What are the specific amino acid sequences that target proteins for nuclear import or export

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called? a) Importins and exportins b) Nuclear pores and nucleoporins c) Nuclear localization signals (NLS) and nuclear export signals (NES) d) Ran and GTP-binding proteins Answer: c) Nuclear localization signals (NLS) and nuclear export signals (NES) What type of amino acid residues are typically found in classic NLS and NES sequences? a) Aspartate and glutamine b) Leucine and serine c) Lysine and arginine d) Proline and tyrosine Answer: c) Lysine and arginine How does Ran-GTP affect the conformation of importin and cargo complex during nuclear transport? a) It has no effect on the complex. b) It causes cargo release from importin. c) It stabilizes the cargo/importin complex. d) It inhibits nucleoporin function. Answer: b) It causes cargo release from importin. Which protein regulates the directionality of movement through the nuclear pore complex during nuclear transport? a) Histone b) Ran-GTP c) Lamin d) GTPase-activating protein (GAP) Answer: b) Ran-GTP What is the primary role of exportins in nuclear transport? a) Importing proteins into the nucleus b) Exporting proteins from the nucleus c) Exporting RNA molecules from the nucleus d) Maintaining nuclear envelope integrity Answer: b) Exporting proteins from the nucleus Which molecule plays a key role in the directionality of nuclear export mediated by exportins? a) ATP b) GTP c) tRNA d) mRNA Answer: b) GTP

How is the stable cargo-exportin complex formed during nuclear export? a) Ran-GTP binding b) Ran-GTP hydrolysis c) Binding to importins d) NTF2 recycling Answer:a) Ran-GTP binding What types of molecules are exported from the nucleus with the assistance of specific exportins? a) Proteins and lipids b) Transfer RNAs (tRNAs) and microRNAs (miRNAs) c) Ribosomal proteins d) DNA molecules Answer: b) Transfer RNAs (tRNAs) and microRNAs (miRNAs) How are ribosomal RNAs (rRNAs) transported to the cytoplasm during ribosome assembly? a) They are transported independently of exportins and Ran. b) They are transported by Crm1 exportin. c) They are transported by NTF2. d) They are transported through passive diffusion. Answer: b) They are transported by Crm1 exportin. What is the role of the mRNA exporter complex in the transport of mRNA molecules from the nucleus? a) It recruits ribosomal proteins to pre-mRNAs. b) It facilitates the transport of ribosomal subunits. c) It remodels mRNA molecules. d) It prevents mRNA transport back to the nucleus. What establishes the directionality of mRNA transport through the nuclear pore complex? a) Ran-GTP binding b) Cytoplasmic RNA helicase c) Exportin interaction d) Nuclear localization signals (NLS) How is Ran-GTP regenerated during nuclear export? a) Ran GAP hydrolysis b) Nucleolar ribosomal protein binding c) Cytoplasmic RNA helicase activity d) Exportin recycling through NTF2 What is the primary function of NF-κB in the cytoplasm? a) To activate IκB b) To mask its NLS

c) To facilitate nuclear import d) To degrade IκB How is NF-κB activated and translocated to the nucleus? a) Phosphorylation of NF-κB b) Phosphorylation of IκB c) Phosphorylation of importin d) Phosphorylation of nuclear pore complex proteins Which exportin is involved in the transport of small nuclear RNAs (snRNAs) from the nucleus to the cytoplasm? a) Exportin Snurportin b) Crm1 exportin c) NTF2 exportin d) Ran-GTP exportin What is the role of Snurportin importin in snRNP transport? a) It mediates the export of snRNAs to the cytoplasm. b) It mediates the transport of snRNPs back into the nucleus. c) It regulates the phosphorylation of snRNPs. d) It prevents snRNAs from binding to snRNP proteins. How does chromatin structure contribute to DNA protection during cell division? a) Chromatin allows DNA strands to become tangled, reducing the risk of damage. b) Chromatin reinforces DNA during division by breaking DNA into smaller fragments. c) Chromatin prevents DNA strands from becoming tangled, thereby protecting them. d) Chromatin enhances the risk of DNA damage during cell division. What are the primary components of chromatin? a) Histone proteins b) Ribosomal RNAs c) Nuclear lamins d) Exportins and importins How is DNA packaged within chromatin to form nucleosomes? a) DNA is wrapped around nuclear pore complexes. b) DNA is wrapped around ribosomal proteins. c) DNA is wrapped around histone proteins. d) DNA is wrapped around nuclear lamins. What critical roles does chromatin play in the regulation of DNA? a) Regulating nuclear protein export b) Regulating ribosome assembly c) Regulating DNA replication and gene expression

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d) Regulating mRNA transport through nuclear pores What is euchromatin, and what distinguishes it from heterochromatin? a) Euchromatin is tightly packed and enriched in genes, while heterochromatin is loosely packed. b) Euchromatin is loosely packed and enriched in genes, while heterochromatin is tightly packed. c) Euchromatin and heterochromatin have the same degree of compaction. d) Euchromatin is not involved in gene regulation. Which core histone proteins are part of nucleosomes? a) H1 and H2 b) H2A, H2B, H3, and H4 c) H3 and H4 d) H1, H2A, H2B, H3, and H4 How do histone "tail" variations impact chromatin structure? a) They have no effect on chromatin structure. b) They determine the overall DNA sequence. c) They can be methylated or acetylated to regulate chromatin compaction and gene expression. d) They are responsible for DNA replication. How are chromosome territories organized within the nucleus? a) They are randomly distributed. b) Their position correlates with their level of transcriptional activity. c) They are always found near the nuclear envelope. d) Their organization is not related to gene expression. What is the role of lamina-associated domains (LADs) in the organization of chromosomes? a) LADs are regions of active transcription. b) LADs interact with the nucleolus. c) Genes found in LADs are generally transcriptionally repressed and associated with heterochromatin. d) LADs are associated with euchromatin. How are boundaries between chromatin domains established in the nucleus? a) Boundaries are randomly formed. b) Boundaries are established by binding to ribosomal proteins. c) Boundaries are formed by Cohesin and the transcriptional activator CTCF. d) Boundaries are determined by DNA replication. Where does DNA replication take place in the nucleus, and what are replication factories?

a) DNA replication occurs throughout the nucleus, evenly distributed. b) Replication factories are regions enriched in inactive RNA polymerases. c) Replication factories are clustered sites where the replication of multiple DNA molecules occurs. d) Replication factories are large organelles surrounded by membranes. What are transcription factories, and why are they important for gene regulation? a) Transcription factories are regions where DNA replication takes place. b) Transcription factories are membrane-bound organelles involved in protein synthesis. c) Transcription factories are clustered sites of active RNA polymerases and transcription factors. d) Transcription factories are storage sites for ribosomes. How are co-regulated genes transcribed in the same transcription factory, and what advantage does this offer? a) Co-regulated genes are transcribed in different factories, ensuring independent regulation. b) Co-regulated genes are not transcribed simultaneously. c) Co-regulated genes share a transcription factory, allowing for coordinated regulation. d) Co-regulated genes are transcribed in the cytoplasm. What are nuclear bodies, and how are they different from cytoplasmic organelles? a) Nuclear bodies are enclosed by membranes, while cytoplasmic organelles are not. b) Nuclear bodies are involved in RNA processing, while cytoplasmic organelles are involved in protein synthesis. c) Nuclear bodies are formed by lipid bilayers, while cytoplasmic organelles are not. d) Nuclear bodies are not enclosed by membranes and are maintained by protein-protein and protein-RNA interactions. What is the most prominent nuclear body and its primary function? a) Cajal body, involved in transcription regulation. b) Clastosomes, responsible for RNA processing. c) Nucleolus, the site of ribosomal RNA transcription/processing and ribosome assembly. d) Speckle, responsible for DNA repair. What is the role of the nucleolus in the cell, and what are its three morphological regions? a) The nucleolus is responsible for DNA replication and contains fibrillar, granular, and membranous regions. b) The nucleolus is the site of ribosomal RNA transcription/processing and ribosome assembly, consisting of the fibrillar center, dense fibrillar component, and granular component. c) The nucleolus stores pre-mRNA splicing factors and contains speckles, paraspeckles, and PML bodies. d) The nucleolus is involved in transcription regulation and is composed of the granular, polycomb, and histone locus bodies.

Pre-rRNA processing involves the action of both proteins and RNAs. What type of RNAs are involved in this process? a) tRNAs b) mRNAs c) snoRNAs d) miRNAs How many proteins are typically found in nucleoli that function in pre-RNA cleavage? a) 10 proteins b) 50 proteins c) >300 proteins d) 200 proteins Ribosome formation involves the assembly of precursor rRNAs with ribosomal proteins. Where are these ribosomal proteins imported from? a) Cytoplasm b) Nucleus c) Mitochondria d) Endoplasmic reticulum What is the function of polycomb proteins in the nucleus? a) Promote gene transcription b) Repress gene transcription c) Initiate DNA replication d) Facilitate mRNA splicing Where are polycomb proteins concentrated within the nucleus? a) In nucleoli b) In nuclear speckles c) In polycomb bodies d) In histone locus bodies Which nuclear bodies are involved in the assembly of small snRNPs responsible for pre-mRNA processing? a) Nucleoli b) Cajal bodies c) Nuclear speckles d) Polycomb bodies What is the role of Cajal bodies in snRNP maturation? a) Export snRNAs to the cytoplasm b) Concentrate snRNPs for final maturation c) Facilitate mRNA translation d) Synthesize ribosomal RNA

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Nuclear speckles contain components of which cellular process? a) DNA replication b) Protein synthesis c) mRNA processing d) Lipid metabolism Which of the following is NOT a type of small RNA found in the nucleus? a) snoRNA b) miRNA c) tRNA d) rRNA

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