Question 1

Neurotransmitters must be removed from the synaptic cleft to:

Accepted Answer

Neurotransmitters must be removed from the synaptic cleft to prevent prolonged stimulation of the postsynaptic cell. If neurotransmitters were not removed from the synaptic cleft, they would continue to bind to the receptors on the postsynaptic cell, leading to excessive stimulation, which can be harmful to the cell. Therefore, the timely removal of neurotransmitters is essential to maintain proper synaptic transmission.

Question 2

Acetylcholinesterase:

Accepted Answer

Acetylcholinesterase is an enzyme that breaks down acetylcholine in the synaptic cleft, terminating the signal between neurons.

Question 3

The members of the protein kinase C family that are regulated by Ca⁺⁺, by diacylglycerol and by phosphatidylserine are called the:

Accepted Answer

The members of the protein kinase C family that are regulated by Ca2+, diacylglycerol, and phosphatidylserine are called conventional PKCs. Atypical PKCs are not regulated by Ca2+, but they are still sensitive to diacylglycerol and phosphatidylserine. Modified PKCs and novel PKCs are not regulated by Ca2+ but are still sensitive to diacylglycerol and phosphatidylserine.

Question 4

The phospholipid that is hydrolyzed to stimulate ceramide-activated protein kinase is:

Accepted Answer

Ceramide-activated protein kinase is stimulated by the hydrolysis of sphingomyelin, making option A the correct choice.

Question 5

Botulism toxin inhibits the potentiation of nerve impulses by interfering with what aspect of acetylcholine signaling?

Accepted Answer

Botulism toxin inhibits the release of acetylcholine by preventing the vesicles containing acetylcholine from fusing with the presynaptic neuronal membrane, thus interfering with the neurotransmitter's ability to signal the next neuron.

Question 6

Transient increases in cytoplasmic Ca²⁺ levels can activate all EXCEPT:

Accepted Answer

The answer of Transient increases in cytoplasmic Ca²⁺ levels can...

Question 7

Calmodulin exhibits all of the following characteristics EXCEPT:

Accepted Answer

The answer of Calmodulin exhibits all of the following characteristics...

Question 8

All are results of the phospholipase C activity mediated by hormone binding, signal transduction and eventually Ca⁺⁺ release into the cytoplasm EXCEPT:

Accepted Answer

The phospholipase C activity mediated by hormone binding, signal transduction, and eventually Ca⁺⁺ release into the cytoplasm can trigger various downstream effects, including the phosphorylation of specific proteins, activation of protein kinases by calcium complexed with calmodulin, the release of diacylglycerol from membrane phospholipids, and the release of IP₃. However, it does not directly result in an increase in guanylyl cyclase activity.

Question 9

The original phorbol esters are natural products that mimic ____ by binding and activating ____ that potentiate the effects of ____.

Accepted Answer

Phorbol esters are natural products that mimic DAG (diacylglycerol) by binding and activating PKC (protein kinase C), which potentiate the effects of carcinogens.

Question 10

Rapid influx of Ca⁺⁺ into the cytoplasm can occur as a result of the binding of hormones to a receptor activating phospholipase C activity. The increased level of Ca⁺⁺ is derived from all of the following EXCEPT:

Accepted Answer

Lysozymes are not involved in the release of Ca⁺⁺ into the cytoplasm. The other options - calciosomes, endoplasmic reticulum, and extracellular stores - are all potential sources of Ca⁺⁺ release upon activation of phospholipase C activity.

Question 11

All are inhibitors of acetylcholinesterase EXCEPT:

Accepted Answer

All are inhibitors of acetylcholinesterase, including sarin, malathion, parathion, and tabun.

Question 12

Lithium salts have been used for years for the treatment of manic depression. Although its mechanism of action at the molecular level is far from clear, it has been shown that Li⁺:

Accepted Answer

Lithium salts have been shown to inhibit enzymes involved in phosphoinositide metabolism, which in turn affects signaling pathways involved in neurotransmission and mood regulation. This is believed to be the main mechanism of action for its effectiveness in treating bipolar disorder.

Question 13

Cancerous tumors may develop from all of the following EXCEPT:

Accepted Answer

All of the statements are true and can contribute to the development of cancerous tumors.

Question 14

In a neuron, when voltage-gated Na⁺ channels have just closed, which of the following is true?

Accepted Answer

When the voltage-gated Na+ channels have just closed, the neuron is in the refractory period, where the membrane potential is less polarized than at rest (-70mV). This is due to the fact that a large influx of positively charged sodium ions depolarizes the membrane potential during depolarization, but the closing of these channels prevents more influx of positively charged sodium, leading to a slight decrease in membrane potential.

Question 15

Calcium binding proteins all possess two or more characteristic peptide domains for Ca⁺⁺ binding that consist of a short α-helix, a loop of 12 amino acids and a second α-helix (helix-loop-helix) that is called:

Accepted Answer

The characteristic peptide domains for calcium binding proteins consist of an α-helix, a loop of 12 amino acids and a second α-helix, also known as the EF hand. The other options are unrelated to the peptide domains for calcium binding.

Question 16

Which of the following statements regarding neurons and the action potential is NOT true?

Accepted Answer

In myelinated axons, sodium channels are not distributed evenly. They are concentrated at the nodes of Ranvier, the gaps in myelin sheath where the action potential is regenerated.

Question 17

____ of Tyr⁵²⁷ in the SH2 domain of protein tyrosine kinase pp60^c⁻^src ____ tyrosine kinase activity by moving an "activation loop" ____ the active site.

Accepted Answer

Phosphorylation of Tyr527 in the SH2 domain of pp60^c-src inhibits tyrosine kinase activity by stabilizing the inactive conformation, moving the activation loop into the active site.

Question 18

During an action potential, which of the following is directly responsible for restoration of resting membrane potential?

Accepted Answer

During an action potential, efflux of K+ ions is directly responsible for restoration of resting membrane potential. As the action potential reaches its peak, voltage-gated K+ channels open and allow K+ ions to flow out of the cell, leading to repolarization of the membrane and restoration of its resting potential.

Question 19

Phospholipase C-γ is activated by ____ while phospholipase C-β is activated by ____.

Accepted Answer

Phospholipase C-γ is activated by receptor tyrosine kinase, while phospholipase C-β is activated by Gα.

Question 20

All are characteristic of EF-hand proteins EXCEPT:

Accepted Answer

All the statements provided are characteristic of EF-hand proteins, making option E correct. EF-hand domains often contact each other, these proteins undergo significant conformational changes upon calcium ion binding, these changes facilitate interaction with target proteins, and CaM, a well-known EF-hand protein, indeed binds to target proteins with basic amphiphilic alpha helix motifs.

Quiz 32: The Reception and Transmission of Extracellular Information

Neurotransmitters must be removed from the synaptic cleft to:

Acetylcholinesterase:

The members of the protein kinase C family that are regulated by Ca⁺⁺, by diacylglycerol and by phosphatidylserine are called the:

The phospholipid that is hydrolyzed to stimulate ceramide-activated protein kinase is:

Botulism toxin inhibits the potentiation of nerve impulses by interfering with what aspect of acetylcholine signaling?

Transient increases in cytoplasmic Ca²⁺ levels can activate all EXCEPT:

Calmodulin exhibits all of the following characteristics EXCEPT:

All are results of the phospholipase C activity mediated by hormone binding, signal transduction and eventually Ca⁺⁺ release into the cytoplasm EXCEPT:

The original phorbol esters are natural products that mimic by binding and activating that potentiate the effects of .

Rapid influx of Ca⁺⁺ into the cytoplasm can occur as a result of the binding of hormones to a receptor activating phospholipase C activity. The increased level of Ca⁺⁺ is derived from all of the following EXCEPT:

All are inhibitors of acetylcholinesterase EXCEPT:

Lithium salts have been used for years for the treatment of manic depression. Although its mechanism of action at the molecular level is far from clear, it has been shown that Li⁺:

Cancerous tumors may develop from all of the following EXCEPT:

In a neuron, when voltage-gated Na⁺ channels have just closed, which of the following is true?

Calcium binding proteins all possess two or more characteristic peptide domains for Ca⁺⁺ binding that consist of a short α-helix, a loop of 12 amino acids and a second α-helix (helix-loop-helix) that is called:

Which of the following statements regarding neurons and the action potential is NOT true?

of Tyr⁵²⁷ in the SH2 domain of protein tyrosine kinase pp60^c⁻^src tyrosine kinase activity by moving an "activation loop" the active site.

During an action potential, which of the following is directly responsible for restoration of resting membrane potential?

Phospholipase C-γ is activated by while phospholipase C-β is activated by .

All are characteristic of EF-hand proteins EXCEPT:

Quiz 32: The Reception and Transmission of Extracellular Information

Neurotransmitters must be removed from the synaptic cleft to:

Acetylcholinesterase:

The members of the protein kinase C family that are regulated by Ca++, by diacylglycerol and by phosphatidylserine are called the:

The phospholipid that is hydrolyzed to stimulate ceramide-activated protein kinase is:

Botulism toxin inhibits the potentiation of nerve impulses by interfering with what aspect of acetylcholine signaling?

Transient increases in cytoplasmic Ca2+ levels can activate all EXCEPT:

Calmodulin exhibits all of the following characteristics EXCEPT:

All are results of the phospholipase C activity mediated by hormone binding, signal transduction and eventually Ca++ release into the cytoplasm EXCEPT:

The original phorbol esters are natural products that mimic ____ by binding and activating ____ that potentiate the effects of ____.

Rapid influx of Ca++ into the cytoplasm can occur as a result of the binding of hormones to a receptor activating phospholipase C activity. The increased level of Ca++ is derived from all of the following EXCEPT:

All are inhibitors of acetylcholinesterase EXCEPT:

Lithium salts have been used for years for the treatment of manic depression. Although its mechanism of action at the molecular level is far from clear, it has been shown that Li+:

Cancerous tumors may develop from all of the following EXCEPT:

In a neuron, when voltage-gated Na+ channels have just closed, which of the following is true?

Calcium binding proteins all possess two or more characteristic peptide domains for Ca++ binding that consist of a short α-helix, a loop of 12 amino acids and a second α-helix (helix-loop-helix) that is called:

Which of the following statements regarding neurons and the action potential is NOT true?

____ of Tyr527 in the SH2 domain of protein tyrosine kinase pp60c−src ____ tyrosine kinase activity by moving an "activation loop" ____ the active site.

During an action potential, which of the following is directly responsible for restoration of resting membrane potential?

Phospholipase C-γ is activated by ____ while phospholipase C-β is activated by ____.

All are characteristic of EF-hand proteins EXCEPT:

The members of the protein kinase C family that are regulated by Ca⁺⁺, by diacylglycerol and by phosphatidylserine are called the:

Transient increases in cytoplasmic Ca²⁺ levels can activate all EXCEPT:

All are results of the phospholipase C activity mediated by hormone binding, signal transduction and eventually Ca⁺⁺ release into the cytoplasm EXCEPT:

The original phorbol esters are natural products that mimic by binding and activating that potentiate the effects of .

Rapid influx of Ca⁺⁺ into the cytoplasm can occur as a result of the binding of hormones to a receptor activating phospholipase C activity. The increased level of Ca⁺⁺ is derived from all of the following EXCEPT:

Lithium salts have been used for years for the treatment of manic depression. Although its mechanism of action at the molecular level is far from clear, it has been shown that Li⁺:

In a neuron, when voltage-gated Na⁺ channels have just closed, which of the following is true?

Calcium binding proteins all possess two or more characteristic peptide domains for Ca⁺⁺ binding that consist of a short α-helix, a loop of 12 amino acids and a second α-helix (helix-loop-helix) that is called:

of Tyr⁵²⁷ in the SH2 domain of protein tyrosine kinase pp60^c⁻^src tyrosine kinase activity by moving an "activation loop" the active site.

Phospholipase C-γ is activated by while phospholipase C-β is activated by .