Which of the following answers describes the most directconsequence of tropomyosin binding to F-actin in muscle cells?
The (-) end of F-actin is stabilized
Loss of actin-ADP subunits from the (+) end is prevented
Myosin binding to F-actin is blocked
ATP hydrolysis by myosin is blocked
The movement of myosin towards the (+) end is blocked
Which of the following answers describes the most directconsequence of tropomyosin binding to F-actin in muscle cells?
The (-) end of F-actin is stabilized |
Loss of actin-ADP subunits from the (+) end is prevented |
Myosin binding to F-actin is blocked |
| ATP hydrolysis by myosin is blocked |
The movement of myosin towards the (+) end is blocked |
Related textbook solutions
Related questions
The vesicles that transport materials from donor membranes to acceptor membranes include:
| 1. | COP-II coated vesicles | |
| 2. | COP-III coated vesicles | |
| 3. | COP-I coated vesicles | |
| 4. | Clathrin coated vesicles |
2.5 points
QUESTION 11
During skeletal muscle contraction, the roles of ATP include:
| 1. | ATP is not required for forming the crossbridges between myosin and actin filaments. | |
| 2. | ATP is utilized as a structural linker to mediate the interaction between myosin and actin filaments | |
| 3. | Hydrolysis of ATP provides energy for myosin head to move along actin filaments and the binding of ATP to myosin head allows the detachment of myosin fromactin filaments. | |
| 4. | ATP binds to actin filaments to drive the power stroke of myosin head. |
2.5 points
QUESTION 12
One of the functions of smooth endoplasmic reticulum is
| 1. | Synthesizing steroid hormone in the endocrine cells of the gonad and adrenal cortex | |
| 2. | Serves as the starting point of the biosynthetic pathway | |
| 3. | Synthesizing secretory proteins | |
| 4. | Degrading cell debris |
2.5 points
QUESTION 13
The function of COP-II coated vesicles is mainly:
| 1. | Transporting materials from endosomes to Golgi complex | |
| 2. | Moving materials from the ER to the ERGIC and Golgi complex. | |
| 3. | Transporting materials from Golgi complex back to endoplasmic reticulum. | |
| 4. | Involved in receptor-mediated endocytosis. |
2.5 points
QUESTION 14
Which of the following processes is completed in rough endoplasmic reticulum?
| 1. | Chaperones help misfolded proteins fold correctly. | |
| 2. | Proteins that target to nucleus are synthesized in rough endoplasmic reticulum. | |
| 3. | O-linked glycosylation occurs in rough endoplasmic reticulum. | |
| 4. | Misfolded proteins are destructed in rough endoplamic reticulum. |
2.5 points
QUESTION 15
Kinesin is the motor protein that coorporates with microtubules. It has the following functions:
| 1. | It uses GTP as energy source. | |
| 2. | It can hydrolyze ATP and use the energy to drive cargo along microtubules from minus end to plus end. | |
| 3. | It has a globular head that can act as GTPase | |
| 4. | The tail of kinesin is more diverse and binds to cargo |
2.5 points
QUESTION 16
For correct segregation and trafficking, lysosomal proteins are tagged in the cis-Golgi with phosphorylated mannose residues, and then the tagged lysosomal enzymes are recruited to clathrin coated vesicles by mannose 6-phosphate receptors.
True
False
2.5 points
QUESTION 17
The process that specialized cells, such macrophages, engulf relatively large particles is:
| 1. | Called pinocytosis | |
| 2. | Called phagocytosis | |
| 3. | Mediated by COP-II coated vesicles | |
| 4. | Called autophagy |
2.5 points
QUESTION 18
Proteins synthesized on rough endoplasmic reticulum and smooth endoplasmic reticulum are imported co-translationally to their destinations
True
False
2.5 points
QUESTION 19
Treatment of cells with a drug that promotes microtubule disassembly disperses Golgi complex into separate stacks of membrane compartments, suggesting that:
| 1. | Golgi complex is made of microtubules. | |
| 2. | Microtubules are important for the organization of Golgi complex. | |
| 3. | Microtubules are transported into Golgi complex | |
| 4. | Golgi complex is composed of tubulin proteins |
2.5 points
QUESTION 20
Which of the following is correct about signal sequence of a secretory protein?
| 1. | It is an âaddress codesâ for protein trafficking pathways | |
| 2. | It is usually located at the C-terminus. | |
| 3. | It targets the ribosome and the protein that is being synthesized to endoplasmic reticulum. | |
| 4. | It is removed in Golgi complex. |
A wound healing assay shows that expression of high GDI levelsproduces defects in cell migration. To assess actin organization inthese cells, you perform immunofluorescence microscopy analysiswith antibodies to actin and an appropriate secondary antibody.This experiment shows that actin organization at the leading edgeof the cell is normal, but that there are significantly fewerstress fibers in the cell body and towards the trailing edge of thecell.
Which of following answer is most consistent with yourobservation?
| GDI overexpression reduces the cytosolic concentration ofG-actin ATP so that F-actin is rapidly depolymerized |
| GDI overexpression stimulates the activity of Rho, which thenbinds to the actin nucleation protein formin to nucleate linearactin filaments |
| GDI prevents a chemoattractant in the medium to bind to thereceptor so that migration cannot occur |
| GDI sequesters the small GTPase Rho in the cytosol so that itcannot be activated by its GEF |
| GDI blocks the activation of Rac at the leading edge of thecell. |
