Biology 2382B Lecture Notes - Lecture 6: Transferrin Receptor, Ldl Receptor, Cholesteryl Ester
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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. |
QUESTION 1
Which of the following is an example of an extracellular signal molecule?
a. | IP3 | |
b. | cAMP | |
c. | Insulin | |
d. | Diacylglycerol |
2 points
QUESTION 2
Nuclear hormone receptors _____
a. | Bind to water soluble ligands | |
b. | Activate second messengers | |
c. | Regulate transcription in response to ligand binding | |
d. | Are normally located on the plasma membrane |
2 points
QUESTION 3
Which of the following does not occur when a receptor tyrosine kinase is bound by ligand?
a. | Phosphorylation of the RTK | |
b. | Cytoplasmic proteins bind the phosphorylated RTK | |
c. | Dimerization of the RTK | |
d. | The RTK binds to DNA to regulate transcription |
2 points
QUESTION 4
Which of these is a logical signal-transduction pathway?
a. | An intracellular receptor activates phospholipase C, which cleaves a membrane protein to form IP3, which then activates the opening of an ER channel protein, which releases cyclic AMP into the cytoplasm, where it binds to an intracellular enzyme that carries out a response. | |
b. | A G-protein-linked receptor activates G protein, which activates phospholipase C, which cleaves a membrane lipid to form IP3, which binds to a calcium channel on the ER, which opens to release calcium ions into the cytoplasm, which bind to an intracellular enzyme that carries out a response. | |
c. | An ion-channel receptor opens, allowing a steroid hormone to enter the cell; the steroid hormone then activates protein kinases that convert GTP to GDP, which binds to an intracellular enzyme that carries out a response. | |
d. | A tyrosine-kinase receptor activates adenylyl cyclase, which activates phospholipase C, which converts ATP into cyclic AMP, which binds to an intracellular enzyme that carries out a response. |
2 points
QUESTION 5
Which of the following is an example of signal amplification?
a. | activation of an enzyme molecule | |
b. | activation of a specific gene by a growth factor | |
c. | Breakdown of many cAMP molecules | |
d. | activation of 100 molecules by a single signal binding event |
2 points
QUESTION 6
Consider a signal transduction pathway that utilizes cAMP as a second messenger to activate PKA (Protein Kinase A). Which of the following situations will result in the cellular response?
The G protein releases GDP and binds to GTP | ||
The target protein (adenylyl cyclase) is inactive | ||
The regulatory subunits of PKA (Protein Kinase A) are bound to the catalytic subunits | ||
The appropriate G protein is bound to GDP |
2 points
QUESTION 7
Which of the following is found in only some signal transduction pathways? [In other words, which is not found in all signal transduction pathways?]
Receptor protein | ||
Extracellular signal molecule | ||
Intracellular signaling molecule | ||
Cellular response | ||
Effector protein |
2 points
QUESTION 8
The enzyme that specifically catalyzes the conversion of ATP to cAMP is:
Adenylyl phosphatase | ||
Adenylyl kinase | ||
Adenylyl dehydrogenase | ||
Adenylyl cyclase |
2 points
QUESTION 9
If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?
It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. | ||
It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. | ||
It would employ a transduction pathway directly from an external messenger. | ||
It would be able to carry out reception and transduction but would not be able to respond to a signal. |
2 points
QUESTION 10
A hormone signal is sent from the brain to other parts of the body via the bloodstream. Why do only certain cells respond to this signal?
Hormones do not last long enough in the bloodstream to stimulate a cellular response | ||
Only cells that have a specific transcription factor gene will be able to respond to the signal | ||
Only cells in the immediate vicinity of the cell sending the signal will respond | ||
Only cells that have a receptor for the specific signal will be able to respond to it |