BIO 315 TEST 3 HW QUESTIONS AND
ANSWERS
Which of the following is not an example of regulated secretion?
Upon insulin signaling, GLUT4 receptors are translocated to the plasma membrane.
All of the above are examples of regulated secretion.
After the arrival of an action potential, synaptic vesicles fuse releasing neurotransmitter
into the synapse.
Newly synthesized plasma membrane proteins are distributed along the cell membrane
following fusion of vesicles. - Correct Answers -Newly synthesized plasma membrane
proteins are distributed along the cell membrane following fusion of vesicles.
LDL is brought into the cell while LDL receptors (LDL-R) are recycled back to the
plasma membrane in a classic example of receptor-mediated endocytosis. Why does
LDL bind LDL-R at the plasma membrane, but dissociate from them inside the early
endosome?
A) Other lipoproteins with higher affinity for LDL-R outcompete LDL inside the early
endosome.
B) LDL has lower affinity for LDL-R in the acidic environment of early endosomes.
C) Early endosomes have a lower pH than the extracellular environment.
D) All of the above.
E) B&C only. - Correct Answers -E) B&C only.
Match each of the following types of endocytic pathways with their corresponding
description:
macropinocytosis
pinocytosis
phagocytosis
receptor-mediated endocytosis
large-scale uptake of extracellular fluid
ingestion of large particles
receptor-mediated endocytosis - used by cells
uptake of plasma membrane along with extracellular fluid
, used by cells to selectively import macromolecules - Correct Answers -
macropinocytosis - large-scale uptake of extracellular fluid
pinocytosis - uptake of plasma membrane along with extracellular fluid
phagocytosis - ingestion of large particles
receptor-mediated endocytosis - used by cells to selectively import macromolecules
Why does the F508del mutation of CFTR reduce the channel's activity on the epical
plasma membrane? - Correct Answers -The protein is misfolded in the ER causing
reduced trafficking of functional CFTR to the plasma membrane.
Which of the following is not an accurate description of cystic fibrosis transmembrane
conductance regulator (CFTR)?
Regulates mucus hydration
Mutations in CFTR are highly associated with cystic fibrosis development.
Anion channel
Transcription factor - Correct Answers -Transcription factor
Which of the following statements best describes the western blotting experiment
below? - Correct Answers -The mutant CFTR proteins cannot be transported to the
plasma membrane under normal circumstance.
Match each of the following modes of extracellular signaling molecules with an accurate
description.
Paracrine
Endocrine
Contact-dependent
Synaptic
- hormones secreted travel long distances through the bloodstream to produce a
systematic response
- neurotransmitters released into the synapse where they bind receptors influencing
likelihood of a post-synaptic neuron to generate an action potential
- Local action is transduced by local mediator molecules
- membrane bound signal molecules on one cell binds to plasma membrane receptors
on another cell - Correct Answers -Paracrine - Local action is transduced by local
mediator molecules
Endocrine - hormones secreted travel long distances through the bloodstream to
produce a systematic response
ANSWERS
Which of the following is not an example of regulated secretion?
Upon insulin signaling, GLUT4 receptors are translocated to the plasma membrane.
All of the above are examples of regulated secretion.
After the arrival of an action potential, synaptic vesicles fuse releasing neurotransmitter
into the synapse.
Newly synthesized plasma membrane proteins are distributed along the cell membrane
following fusion of vesicles. - Correct Answers -Newly synthesized plasma membrane
proteins are distributed along the cell membrane following fusion of vesicles.
LDL is brought into the cell while LDL receptors (LDL-R) are recycled back to the
plasma membrane in a classic example of receptor-mediated endocytosis. Why does
LDL bind LDL-R at the plasma membrane, but dissociate from them inside the early
endosome?
A) Other lipoproteins with higher affinity for LDL-R outcompete LDL inside the early
endosome.
B) LDL has lower affinity for LDL-R in the acidic environment of early endosomes.
C) Early endosomes have a lower pH than the extracellular environment.
D) All of the above.
E) B&C only. - Correct Answers -E) B&C only.
Match each of the following types of endocytic pathways with their corresponding
description:
macropinocytosis
pinocytosis
phagocytosis
receptor-mediated endocytosis
large-scale uptake of extracellular fluid
ingestion of large particles
receptor-mediated endocytosis - used by cells
uptake of plasma membrane along with extracellular fluid
, used by cells to selectively import macromolecules - Correct Answers -
macropinocytosis - large-scale uptake of extracellular fluid
pinocytosis - uptake of plasma membrane along with extracellular fluid
phagocytosis - ingestion of large particles
receptor-mediated endocytosis - used by cells to selectively import macromolecules
Why does the F508del mutation of CFTR reduce the channel's activity on the epical
plasma membrane? - Correct Answers -The protein is misfolded in the ER causing
reduced trafficking of functional CFTR to the plasma membrane.
Which of the following is not an accurate description of cystic fibrosis transmembrane
conductance regulator (CFTR)?
Regulates mucus hydration
Mutations in CFTR are highly associated with cystic fibrosis development.
Anion channel
Transcription factor - Correct Answers -Transcription factor
Which of the following statements best describes the western blotting experiment
below? - Correct Answers -The mutant CFTR proteins cannot be transported to the
plasma membrane under normal circumstance.
Match each of the following modes of extracellular signaling molecules with an accurate
description.
Paracrine
Endocrine
Contact-dependent
Synaptic
- hormones secreted travel long distances through the bloodstream to produce a
systematic response
- neurotransmitters released into the synapse where they bind receptors influencing
likelihood of a post-synaptic neuron to generate an action potential
- Local action is transduced by local mediator molecules
- membrane bound signal molecules on one cell binds to plasma membrane receptors
on another cell - Correct Answers -Paracrine - Local action is transduced by local
mediator molecules
Endocrine - hormones secreted travel long distances through the bloodstream to
produce a systematic response
