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Dec 6, 2023

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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
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
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