Cytochrome c carries electron from
A. the cytochrome c oxidase complex to the NADH dehydrogenase complex
B. the cytochrome c reductase complex to the cytochrome c oxidase complex
C. the cytochrome c oxidase complex to the cytochrome c reductase complex
D.
B
Which of the following is true regarding proton pumping by the complexes of the mitochondrial electron chain?
A. only the cytochrome c oxidase complex pumps H+, from the intermembrane space into the matrix
B. only the NADH dehydrogenase complex pumps H+,
D
Which part of the mitochondrial ATP synthase binds H+ and interacts with the a subunit to transport the H+ concentration gradient, in order to drive ATP synthesis?
A. the gamma subunit
B. the beta subunit
C. the b subunit
D. the alpha subunit
E. the c sub
E
When a G-protein-coupled receptor is activated by binding a signal molecule, the receptor then activates a G-protein by
A. using its protein kinase activity to phosphorylate the alpha subunit of a G-protein
B. using its protein phosphatase activity to rem
E
Elucidating the Sevenless RTK pathway was challenging because the proteins are present is very small amounts in certain cells, and are activated for only a short time. After isolating the Sevenless mutant, researchers found a second mutation in the same l
C
The regulatory GTPase called Ras is estimated to be responsible for 30% of human cancers. Most mutations in Ras prevent the Ras protein from binding a GTPase-activating protein (GAP). What is the effect of this mutation on signal transduction?
A. The Ras
C
Which of the following events occurs in the nucleus?
A. Ran-GDP binds the nuclear import receptor, causing the receptor to release its cargo
B. Ran-GAP activates the GTPase activity of Ran
C. the nuclear import receptor hydrolyzes a molecule of ATP in ord
D
The role of the signal recognition particle (SRP) in sorting proteins that contain an ER signal sequence is
A. the SRP binds the signal sequence in the cytosol after synthesis of the protein has begun on a ribosome, and escorts the ribosome/mRNA complex t
A
Dr. Guenter Blobel proposed his "signal hypothesis" in 1971, based on his experiments with in vitro (in the test tube) synthesis of an antibody. In living cells, the large and small subunits of the antibody he was studying, which is secreted from cells, w
D
What is the source of energy that is coupled to the transport of a polypeptide through the translocator into the lumen of the endoplasmic reticulum?
A. GTP hydrolysis during translation of the polypeptide by the attached ribosome
B. Hydrolysis of GTP by t
A
Each subunit of an ABC transporter contains six ? helices that span the plasma membrane. Which combination of signal sequences would result in this structure?
A. A single N-terminal start-transfer sequence (not cleaved)
B. An N-terminal start-transfer seq
C
The signal sequence found in proteins that are sorted to the matrix of the mitochondrion is
A. five adjacent (+)-charged amino acids found anywhere within the protein sequence; this signal sequence is cleaved from the protein by a signal peptidase in the
C
Most mutations in the cystic fibrosis transmembrane conductance regulator protein (CFTR) that result in cystic fibrosis would produce a slightly mis-folded form of this ABC transporter for chloride ions in the lungs. The mutant protein would function norm
A
Clathrin coats
A. are found on vesicles that bud from coated pits in the plasma membrane
B. are found on vesicles that travel from the trans Golgi apparatus to early endosomes
C. contain 36 three-legged clathrin triskelions that assemble into a soccer bal
E
An amazing thing occurs when a COPII vesicle buds from the endoplasmic reticulum membrane. The aqueous-soluble Sar1 protein found in the cytosol becomes an ER membrane protein! This transformation of Sar1 is triggered when Sar1
A. Binds the cargo for the
D
Endoplasmic reticulum (ER)-"resident" proteins contain a signal sequence of four amino acids called the KDEL signal. How does the KDEL signal keep ER-resident proteins within the ER?
A.the KDEL signal, found at the C-terminal of an ER-resident protein, is
B
The mannose 6-phosphate receptor releases lysosomal proteins such as acid hydrolase precursors in the endosome because
A. the pH is slightly basic, between 7.5 to 8
B. the mannose 6-phosphate receptor is degraded in the endosome, and thereby releases the
C
The transmembrane KDEL receptor is abundant in the Golgi, but does not return to the ER unless it has bound a soluble ER protein. Why do you think the KDEL receptor only returns to the ER after it has bound an ER protein in the Golgi?
A. Binding the ER pr
A