1. You have isolated two fractions containing similar-sized vesicles by centrifu
ID: 211989 • Letter: 1
Question
1. You have isolated two fractions containing similar-sized vesicles by centrifugation. You suspect one fraction contains lysosomes and the other contains peroxisomes. To confirm that a fraction contains lysosomes, you could test for the presence for which of the following proteins?
a-Actin.
b-ATP synthase.
c-DNA polymerase.
d-Catalase.
e-Acid phosphatase.
2. You have genetically engineered green fluorescent protein (GFP) containing a KDEL sequence (GFP-KDEL). When GFP-KDEL is expressed in normal human fibroblasts and examined using fluorescence microscopy, the fluorescence appears diffuse across the cytoplasm. How would you explain this observations given that KDEL is supposed to be an ER-specific sorting sequence?
a-A. This engineered GFP would not have a hydrophobic signal sequence to get it into the RER in the first place.
b-B. The KDEL sequence would not be recognized because the protein is not in the right compartment.
c-C. This engineered GFP would be synthesized on cytosolic ribosomes.
d-Both A and B.
e-A, B and C.
3. The presence of clathrin mediates vesicular transport _____.
a-from the ER to the cis-Golgi.
b-the plasma membrane to trans-Golgi.
c-the cis-Golgi to the trans-Golgi.
d-the trans-Golgi to a lysosome.
e-the nuclear membrane to an endosome.
4. Mannose 6-phosphate is an important residue, as it is required to target soluble enzymes to the lysosome. The enzymes responsible for attaching this residue onto these soluble enzymes reside in the _____.
a-rough ER.
b-trans-Golgi.
c-cytosol.
d-medial-Golgi.
e-cis-Golgi.
5. Which signal(s) does AQP1, a kidney-specific aquaporin, have?
a- ER signal sequence and NLS.
b-ER signal sequence, KDEL, and mannose-6-phosphate.
c-ER signal sequence and KKXX.
d-ER signal sequence.
e-ER signal sequence and mannose-6-phosphate.
6. In eukaryotes, ribosomes become associated with endoplasmic reticulum membranes when _____.
a-a signal sequence on the ribosome interacts with the SRP receptor on the ER membrane.
b-a signal sequence on the protein being synthesized interacts with the SRP receptor on the ribosome.
c-a signal sequence on the mRNA interacts with the SRP receptor on the ER membrane.
d-the messenger RNA passes through the translocon in the ER membrane.
e-a signal sequence at the N-terminus of the protein being synthesized interacts with a signal recognition particle, which in turn binds to the SRP receptor on the ER membrane.
7. In eukaryotic cells, sugar residues are covalently attached to proteins in the process of N-linked glycosylation, a posttranslational modification that occurs _____.
a-in the cytoplasm.
b-in the Golgi apparatus.
c-in the nucleus.
d-in the rough ER.
e-at the plasma membrane.
8.
Tay-Sachs disease is a rare inherited disorder that progressively destroys nerve cells in the brain and spinal cord. Tay–Sachs disease is caused by insufficient activity of the enzyme hexosaminidase A (a vital hydrolytic enzyme), which in turn results in the failure of lipids being broken down. Which cellular organelle is most likely to be directly involved in this disease?
a-Peroxisome.
b-Golgi apparatus.
c-Rough ER.
d-Lysosome.
e-Smooth ER.
9.
Three major groups of filament systems comprising the cytoskeleton are all composed of polymers of assembled subunits, which when assembled have varying thickness. Which is the correct order, from smallest to largest, of the filament systems?
a-microfilaments, intermediate filaments, microtubules.
b-microtubules, microfilaments, intermediate filaments.
c-microfilaments, microtubules, intermediate filaments.
d-microtubules, intermediate filaments, microfilaments.
e-intermediate filaments, microtubules, microfilaments.
10. Which region of myosin interacts with actin filaments?
a-The lever domain.
b-The light chains.
c-The motor domain.
d-The tail domain.
e-The stalk domain.
11. Which of the following statements does not accurately describe Kinesin-1?
a-Kinesin-1 is a minus (?) end-directed motor.
b-Kinesin-1 transports vesicles along microtubules.
c-Kinesin-1 binds and hydrolyzes ATP to produce movement.
d-Kinesin-1 contains two head groups.
e-Each of the statements above accurately describes Kinesin-1.
12.
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. Vinblastine is a chemotherapy medication used to treat some forms of cancer, including non-small cell lung cancer, bladder cancer, brain cancer and melanoma. Vinblastine inhibits microtubule polymerization. Cancer cells given vinblastine would be unable to _____.
a-extend lamellipodia to facilitate crawling.
b-maintain a spherical nucleus.
c-undergo cytokinesis.
d-form microvilli.
e-separate chromosomes during cell division.
Explanation / Answer
Answer 1 e) Acid phosphatase
Reason- Acid phosphatase is the molecular marker for the lysosomes identification, while catalase is the molecular marker for the peroxisome identification. though actin and polymerase enzymes can be found in many other cells. also, ATP synthase is a specific marker for the mitochondria.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.