Home » What did I learn? Score Your Quiz (Module 4)

What did I learn? Score Your Quiz (Module 4)

Hydrolysis of the neurotransmitter acetycholine is facilitated by the enzyme acetylcholinesterase. For hydrolysis of acetylcholine to occur, which of the following molecules is required?
1. Choline
  Try again. Hydrolysis is a process that involves water. A molecule such as acetylcholine is cleaved into two parts by reacting with water. Water forms a bond between one of its H atoms and part of the molecule and it forms a bond between its OH group and the other part of the molecule, causing the molecule to split. Acetylcholine is split, forming choline and acetic acid.
2. Water
  Good answer! Hydrolysis is a process that involves water. A molecule such as acetylcholine is cleaved into two parts by reacting with water. Water forms a bond between one of its H atoms and part of the molecule and it forms a bond between its OH group and the other part of the molecule, causing the molecule to split. Acetylcholine is split, forming choline and acetic acid.
3. Acetic acid
  Try again. Hydrolysis is a process that involves water. A molecule such as acetylcholine is cleaved into two parts by reacting with water. Water forms a bond between one of its H atoms and part of the molecule and it forms a bond between its OH group and the other part of the molecule, causing the molecule to split. Acetylcholine is split, forming choline and acetic acid.
4. Nerve Gas
  Try again. Hydrolysis is a process that involves water. A molecule such as acetylcholine is cleaved into two parts by reacting with water. Water forms a bond between one of its H atoms and part of the molecule and it forms a bond between its OH group and the other part of the molecule, causing the molecule to split. Acetylcholine is split, forming choline and acetic acid.
Like acetylcholine, nerve gas also binds to the enzyme acetycholinesterase but it is bound with a different kind of bond that prevents the breakdown of acetylcholine by the enzyme. What kind of bond is formed between nerve gas and acetylcholinesterase?
1. Covalent and reversible
  You are half correct. Nerve gases have a phosphorus group that is highly attracted to an OH group on the enzyme. The bond is so strong that, for most types of nerve gases, it can’t be broken. This is called a covalent bond. Since the bond between the phosphorus atom of the nerve gas and the enzyme can’t be broken (i.e., irreversible), the enzyme is no longer able to interact with acetylcholine.
2. Electrostatic and reversible
  Sorry! Nerve gases have a phosphorus group that is highly attracted to an OH group on the enzyme. The bond is so strong that, for most types of nerve gases, it can’t be broken. This is called a covalent bond. Since the bond between the phosphorus atom of the nerve gas and the enzyme can’t be broken (i.e., irreversible), the enzyme is no longer able to interact with acetylcholine. In contast, when acetylcholine binds to acetylcholinesterase, the bonds are electrostatic and reversible in nature.
3. An irreversible hydrogen bond
  Sorry, that is incorrect. Nerve gases have a phosphorus group that is highly attracted to an OH group on the enzyme. The bond is so strong that, for most types of nerve gases, it can’t be broken. This is called a covalent bond. Since the bond between the phosphorus atom of the nerve gas and the enzyme can’t be broken (i.e., irreversible), the enzyme is no longer able to interact with acetylcholine.
4. Covalent and irreversible
  You’re right! Nerve gases have a phosphorus group that is highly attracted to an OH group on the enzyme. The bond is so strong that, for most types of nerve gases, it can’t be broken. This is called a covalent bond. Since the bond between the phosphorus atom of the nerve gas and the enzyme can’t be broken (i.e., irreversible), the enzyme is no longer able to interact with acetylcholine.
In this module, you learned that the neurotransmitter acetylcholine can produce a variety of effects on the body. Acetylcholine produces all of the effects below except:
1. Bronchial constriction (inhibited breathing)
  Not quite. Acetylcholine causes smooth muscle contractions, resulting in bronchial constriction. This is part of its action within the parasympathetic nervous system.
2. Lacrimation (tears)
  No, try again. Acetylcholine causes secretion, resulting in lacrimation or tearing. This is part of its action within the parasympathetic nervous system.
3. Salivation
  Sorry! Acetylcholine causes secretion from glands throughout the body, including the salivary gland. This is part of its action within the parasympathetic nervous system.
4. Constipation
  Bravo! Acetylcholine causes intestinal smooth muscle contractions, resulting in diarrhea and not constipation. This is part of its action within the parasympathetic nervous system.
One of the reasons that nerve gas is so poisonous is its ability to get into the human body quickly in many ways: absorption through the skin, inhalation into the lungs, and entrance through the eyes. Once in the body, the drug easily reaches the brain, diffusing readily through the brain’s protective membrane (the blood-brain barrier). Which property of nerve gas allows for its rapid penetration into the brain?
1. Its phosphorous group
  Try again. The phosphorus group allows nerve gas to bind irreversibly to acetylcholinesterase, preventing it from hydrolyzing acetylcholine. The brain capillaries provide protection to the brain because the endothelial cells are packed tightly together. Therefore, only compounds that are highly lipophilic or non-polar, such as nerve gas, can enter the brain by diffusing through the capillary membranes. Lipophilic compounds also penetrate eyes and skin readily, passing easily through the lipid membranes of those tissues.
2. Its lipophilic (non-polar) nature
  Correct! The brain capillaries provide protection to the brain because the endothelial cells are packed tightly together. Therefore, only compounds that are highly lipophilic or non-polar, such as nerve gas, can enter the brain by diffusing through the capillary membranes. Lipophilic compounds also penetrate eyes and skin readily, passing easily through the lipid membranes of those tissues.
3. The fact that it is odorless
  Try again. While nerve gas is indeed odorless, this does not affect its ability to cross cell membranes. The brain capillaries provide protection to the brain because the endothelial cells are packed tightly together. Therefore, only compounds that are highly lipophilic or non-polar, such as nerve gas, can enter the brain by diffusing through the capillary membranes. Lipophilic compounds also penetrate eyes and skin readily, passing easily through the lipid membranes of those tissues.
The peripheral nervous system includes neurons that connect the brain and spinal cord to muscles, organs and skin to send sensory and motor information. Based on your knowledge of the nervous system, which branch of the peripheral nervous system is responsible for controlling voluntary movement?
1. The parasympathetic nervous system
  Sorry, try again. The parasympathetic nervous system is responsible for involuntary organ function. As part of the autonomic nervous system, the parasympathetic system is active all of the time.
2. The autonomic nervous system
  No, try again. The autonomic nervous system includes only the parasympathetic and sympathetic branches. These branches of the peripheral nervous system help smooth muscles and other organs receive information from the brain and spinal cord to control mostly involuntary organ function.
3. The sympathetic nervous system
  Sorry, try again. The sympathetic nervous system is responsible for involuntary organ function. As part of the autonomic nervous system, the sympathetic system is activated during stressful situations.
4. The somatic nervous system
  Good answer! The somatic nervous system is responsible for controlling voluntary movement. Neurons arising in the spinal cord (motor nerves) connect to skeletal muscles, bringing information to the muscles to contract.
Nerve gases are extremely toxic; a small droplet can kill a person. They exist in both liquid and gaseous forms. Inside closed containers, the nerve gases are in liquid form. However, they when exposed to air, they:
1. 1. Vaporize due to their very high vapor pressure
  Very good! The high vapor pressure of nerve gases causes them to vaporize upon contact with air. Additionally, since nerve gases are much more dense than air, they hover near the ground, where both humans and animals are more likely to be poisoned.
2. Vaporize due to their very low vapor pressure
  Sorry, that’s not right. The high vapor pressure of nerve gases causes them to vaporize upon contact with air. Additionally, since nerve gases are much more dense than air, they hover near the ground, where both humans and animals are more likely to be poisoned.
3. Remain in the liquid state
  Sorry, try again. The high vapor pressure of nerve gases causes them to vaporize upon contact with air. Additionally, since nerve gases are much more dense than air, they hover near the ground, where both humans and animals are more likely to be poisoned.
4. Vaporize due to their dense nature
  No, try again. The high vapor pressure of nerve gases causes them to vaporize upon contact with air. Additionally, since nerve gases are much more dense than air, they hover near the ground, where both humans and animals are more likely to be poisoned.