Which of the following statements about peroxisomes is false?

Which of the following statements about peroxisomes is false?

(a) Most peroxisomal proteins are synthesized in the ER.
(b) Peroxisomes synthesize phospholipids for the myelin sheath.
(c) Peroxisomes produce hydrogen peroxide.
(d) Vesicles that bud from the ER can mature into peroxisomes.

Answer: 

Which of the following statements about transport into mitochondria and chloroplasts is false?

Which of the following statements about transport into mitochondria and chloroplasts is false?

(a) The signal sequence on proteins destined for these organelles is recognized by a receptor protein in the outer membrane of these organelles.
(b) After a protein moves through the protein translocator in the outer membrane of these organelles, the protein diffuses in the lumen until it encounters a protein translocator in the inner membrane.
(c) Proteins that are transported into these organelles are unfolded as they are being transported.
(d) Signal peptidase will remove the signal sequence once the protein has been imported into these organelles.

Answer: 

Which of the following statements is true?

Which of the following statements is true?

(a) The signal sequences on mitochondrial proteins are usually at the C-terminus.
(b) Most mitochondrial proteins are not imported from the cytosol but are synthesized inside the mitochondria.
(c) Chaperone proteins in the mitochondria facilitate the movement of proteins across the outer and inner mitochondrial membranes.
(d) Mitochondrial proteins cross the membrane in their native, folded state.

Answer: 

Your friend works in a biotechnology company and has discovered a drug that blocks the ability of Ran to exchange GDP for GTP. What is the most likely effect of this drug on nuclear transport?

Your friend works in a biotechnology company and has discovered a drug that blocks the ability of Ran to exchange GDP for GTP. What is the most likely effect of this drug on nuclear transport?

(a) Nuclear transport receptors would be unable to bind cargo.
(b) Nuclear transport receptors would be unable to enter the nucleus.
(c) Nuclear transport receptors would be unable to release their cargo in the nucleus.
(d) Nuclear transport receptors would interact irreversibly with the nuclear pore fibrils.

Answer: 

A large protein that passes through the nuclear pore must have an appropriate _________.

A large protein that passes through the nuclear pore must have an appropriate _________.

(a) sorting sequence, which typically contains the positively charged amino acids lysine and arginine.
(b) sorting sequence, which typically contains the hydrophobic amino acids leucine and isoleucine.
(c) sequence to interact with the nuclear fibrils.
(d) Ran-interacting protein domain.

Answer: 

Which of the following statements about nuclear transport is true?

Which of the following statements about nuclear transport is true?

(a) mRNAs and proteins transit the nucleus through different types of nuclear pores.
(b) Nuclear import receptors bind to proteins in the cytosol and bring the proteins to the nuclear pores, where the proteins are released from the receptors into the pores for transit into the nucleus.
(c) Nuclear pores have water-filled passages that small, water-soluble molecules can pass through in a nonselective fashion.
(d) Nuclear pores are made up of many copies of a single protein.

Answer: 

What is the role of the nuclear localization sequence in a nuclear protein?

What is the role of the nuclear localization sequence in a nuclear protein?

(a) It is bound by cytoplasmic proteins that direct the nuclear protein to the nuclear pore.
(b) It is a hydrophobic sequence that enables the protein to enter the nuclear membranes.
(c) It aids in protein unfolding so that the protein can thread through nuclear pores.
(d) It prevents the protein from diffusing out of the nucleus through nuclear pores.

Answer: