Ch. 11 The Nucleus The Nuclear Envelope and Traffic between the Nucleus and Cytoplasm

Which of the following is a nuclear lamina disease? a. Emery-Dreifuss muscular dystrophy b. Charcot-Marie-Tooth disorder type 2B1 c. Hutchinson-Gilford progeria syndrome d. All of the above

d. All of the above

The principal difference between eukaryotic and prokaryotic cells is that eukaryotic cells have a. larger ribosomes than prokaryotic cells. b. cell walls, while prokaryotic cells do not. c. DNA replication and transcription in the same compartment, while prokaryotic cells do not. d. a nucleus, while prokaryotic cells do not.

d. a nucleus, while prokaryotic cells do not.

The nuclear lamina binds to a. both the inner nuclear envelope membrane and the chromatin. b. the inner nuclear envelope only. c. the chromatin only. d. neither the inner nuclear envelope nor the chromatin.

a. both the inner nuclear envelope membrane and the chromatin.

The associations of lamins with the inner nuclear envelope membrane is via a. lamin binding to proteins in the nuclear envelope membrane. b. GPI anchors on lamins. c. lipid tails on lamins. d. Both a and c

a. lamin binding to proteins in the nuclear envelope membrane.

The nuclear lamina is built of proteins called a. lamins. b. laminins. c. nucleins. d. nucleoplasmins.

a. lamins.

What localization occurs for proteins that are normally nuclear when their nuclear localization signal is deleted and the protein is injected into the cytoplasm of cultured cells? a. Nucleus b. Cytoplasm c. In a ring around the outside of the nuclear envelope d. Extracellular

b. Cytoplasm

The nuclear localization signal is recognized by and binds to which protein in the process of nuclear protein import? a. Ran b. Importin c. Exportin d. The outer fibril protein

b. Importin

Nuclear pores are organized with _______ symmetry. a. sixfold b. eightfold c. ninefold d. tenfold

b. eightfold

Highly condensed, transcriptionally inactive chromatin is called a. euchromatin. b. heterochromatin. c. a chromatin domain. d. histone-containing chromatin.

b. heterochromatin.

The nuclear envelope is continuous with the a. mitochondrial outer membrane. b. rough endoplasmic reticulum. c. Golgi apparatus. d. plasma membrane.

b. rough endoplasmic reticulum.

By restricting the traffic of proteins and RNA across the nuclear envelope, eukaryotic cells can regulate a. translation. b. transcription. c. endocytosis. d. nuclear pH.

b. transcription. a. translation.

The directionality of nuclear transport is determined by _______ in the nucleus and _______ in the cytosol. a. high Ran; low Ran b. low Ran; high Ran c. high Ran/GTP; high Ran/GDP d. high Ran/GDP; high Ran/GTP

c. high Ran/GTP; high Ran/GDP

The filaments of the nuclear lamina are composed of a type of a. microfilament. b. microtubule. c. intermediate filament. d. thick filament.

c. intermediate filament.

The major pathway for molecules to pass into and out of the nucleus is through a. gap junctions between the nuclear envelope membranes. b. porin channels in the nuclear envelope membranes. c. nuclear pore complexes. d. diffusion through the membrane bilayers of the nuclear envelope.

c. nuclear pore complexes.

Export of RNAs from the nucleus occurs primarily by a. passive diffusion through nuclear pore complexes. b. cotranscriptional insertion through nuclear envelope membrane protein pores. c. selective transport through nuclear pore complexes in association with proteins. d. release from the nucleus when it breaks down at mitosis.

c. selective transport through nuclear pore complexes in association with proteins.

The nuclear localization signal is typically a(n) _______, rich in the amino acids _______. a. α-helix; Pro, Lys, and Arg b. α-helix; Leu, Phe, and Gly c. short chain; Lys and Arg d. short chain; Phy and Gly

c. short chain; Lys and Arg

Nuclear localization signals were first identified by Alan Smith and his colleagues in the protein a. nucleoplasmin. b. histone H1. c. lamin B. d. SV40 T antigen

d. SV40 T antigen

Transport of RNAs out of the nucleus involves all but which of the following? a. Ran b. Expenditure of chemical energy c. Protein translocation signals d. Small RNAs crossing by passive diffusion

d. Small RNAs crossing by passive diffusion

snRNAs are synthesized in the a. nucleus and function in the cytoplasm. b. cytoplasm and function in the nucleus. c. nucleus and function in the nucleus without passing into the cytoplasm. d. nucleus, move to the cytoplasm to pick up proteins to become functional, and thenreturn to the nucleus.

d. nucleus, move to the cytoplasm to pick up proteins to become functional, and then return to the nucleus.

Small molecules (molecules < 20 kd) enter nuclei by way of a. passive diffusion through nuclear pore complexes. b. selective transport through nuclear pore complexes. c. active transport across the nuclear envelope membranes. d. passive diffusion across the nuclear envelope membranes

d. passive diffusion across the nuclear envelope membranes