Cellular Structures and Organelles - MCAT Biological and Biochemical Foundations of Living Systems
Card 1 of 1016
Which of the following criteria does not help differentiate between prokaryotes and eukaryotes?
Which of the following criteria does not help differentiate between prokaryotes and eukaryotes?
Tap to reveal answer
Cell walls are present in virtually all prokaryotic cells, but are also found in certain eukayotic domains (such as plants and fungi). As such, the presence of a cell wall cannot be used to distinguish between prokaryotic and eukaryotic cells.
Cell walls are present in virtually all prokaryotic cells, but are also found in certain eukayotic domains (such as plants and fungi). As such, the presence of a cell wall cannot be used to distinguish between prokaryotic and eukaryotic cells.
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Prions are the suspected cause of a wide variety of neurodegenerative diseases in mammals. According to prevailing theory, prions are infectious particles made only of protein and found in high concentrations in the brains of infected animals. All mammals produce normal prion protein, PrPC, a transmembrane protein whose function remains unclear.
Infectious prions, PrPRes, induce conformational changes in the existing PrPC proteins according to the following reaction:
PrPC + PrPRes → PrPRes + PrPRes
The PrPRes is then suspected to accumulate in the nervous tissue of infected patients and cause disease. This model of transmission generates replicated proteins, but does so bypassing the standard model of the central dogma of molecular biology. Transcription and translation apparently do not play a role in this replication process.
This theory is a major departure from previously established biological dogma. A scientist decides to test the protein-only theory of prion propagation. He establishes his experiment as follows:
Homogenized brain matter of infected rabbits is injected into the brains of healthy rabbits, as per the following table:
Rabbit 1 and 2: injected with normal saline on days 1 and 2
The above trials serve as controls.
Rabbit 3 and 4: injected with homogenized brain matter on days 1 and 2
The above trials use unmodified brain matter.
Rabbit 5 and 6: injected with irradiated homogenized brain matter on days 1 and 2
The above trials use brain matter that has been irradiated to destroy nucleic acids in the homogenate.
Rabbit 7 and 8: injected with protein-free centrifuged homogenized brain matter on days 1 and 2
The above trials use brain matter that has been centrifuged to generate a protein-free homogenate and a protein-rich homogenate based on molecular weight.
Rabbit 9 and 10: injected with boiled homogenized brain matter on days 1 and 2
The above trials use brain matter that have been boiled to destroy any bacterial contaminants in the homogenate.
Another experiment shows that PrPC reacts with hormones that circulate among nervous tissue. As a transmembrane protein, what kinds of hormones are most likely to interact with PrPC?
I. Peptide hormones
II. Catecholamines
III. Steroid Hormones
Prions are the suspected cause of a wide variety of neurodegenerative diseases in mammals. According to prevailing theory, prions are infectious particles made only of protein and found in high concentrations in the brains of infected animals. All mammals produce normal prion protein, PrPC, a transmembrane protein whose function remains unclear.
Infectious prions, PrPRes, induce conformational changes in the existing PrPC proteins according to the following reaction:
PrPC + PrPRes → PrPRes + PrPRes
The PrPRes is then suspected to accumulate in the nervous tissue of infected patients and cause disease. This model of transmission generates replicated proteins, but does so bypassing the standard model of the central dogma of molecular biology. Transcription and translation apparently do not play a role in this replication process.
This theory is a major departure from previously established biological dogma. A scientist decides to test the protein-only theory of prion propagation. He establishes his experiment as follows:
Homogenized brain matter of infected rabbits is injected into the brains of healthy rabbits, as per the following table:
Rabbit 1 and 2: injected with normal saline on days 1 and 2
The above trials serve as controls.
Rabbit 3 and 4: injected with homogenized brain matter on days 1 and 2
The above trials use unmodified brain matter.
Rabbit 5 and 6: injected with irradiated homogenized brain matter on days 1 and 2
The above trials use brain matter that has been irradiated to destroy nucleic acids in the homogenate.
Rabbit 7 and 8: injected with protein-free centrifuged homogenized brain matter on days 1 and 2
The above trials use brain matter that has been centrifuged to generate a protein-free homogenate and a protein-rich homogenate based on molecular weight.
Rabbit 9 and 10: injected with boiled homogenized brain matter on days 1 and 2
The above trials use brain matter that have been boiled to destroy any bacterial contaminants in the homogenate.
Another experiment shows that PrPC reacts with hormones that circulate among nervous tissue. As a transmembrane protein, what kinds of hormones are most likely to interact with PrPC?
I. Peptide hormones
II. Catecholamines
III. Steroid Hormones
Tap to reveal answer
Students should know that peptide hormones (and catecholamines, but this is not required to answer the question correctly as written here) interact with surface receptors and do not freely go through a membrane. They must interact with the transmembrane surface receptors to initiate a signal transduction cascade. In contrast, steroid hormones can bypass the transmembrance protein receptors by freely diffusing across the memberane, due to their small, nonpolar nature. In this case, only peptide hormones and catecholamines will require the facilitated diffusion mechanism provided by a transmembrane protein.
Students should know that peptide hormones (and catecholamines, but this is not required to answer the question correctly as written here) interact with surface receptors and do not freely go through a membrane. They must interact with the transmembrane surface receptors to initiate a signal transduction cascade. In contrast, steroid hormones can bypass the transmembrance protein receptors by freely diffusing across the memberane, due to their small, nonpolar nature. In this case, only peptide hormones and catecholamines will require the facilitated diffusion mechanism provided by a transmembrane protein.
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Scientists use a process called Flourescent In-Situ Hybridization, or FISH, to study genetic disorders in humans. FISH is a technique that uses spectrographic analysis to determine the presence or absence, as well as the relative abundance, of genetic material in human cells.
To use FISH, scientists apply fluorescently-labeled bits of DNA of a known color, called probes, to samples of test DNA. These probes anneal to the sample DNA, and scientists can read the colors that result using laboratory equipment. One common use of FISH is to determine the presence of extra DNA in conditions of aneuploidy, a state in which a human cell has an abnormal number of chromosomes. Chromosomes are collections of DNA, the totality of which makes up a cell’s genome. Another typical use is in the study of cancer cells, where scientists use FISH labels to ascertain if genes have moved inappropriately in a cell’s genome.
Using red fluorescent tags, scientists label probe DNA for a gene known to be expressed more heavily in cancer cells than normal cells. They then label a probe for an immediately adjacent DNA sequence with a green fluorescent tag. Both probes are then added to three dishes, shown below. In dish 1 human bladder cells are incubated with the probes, in dish 2 human epithelial cells are incubated, and in dish 3 known non-cancerous cells are used. The relative luminescence observed in regions of interest in all dishes is shown below.
The bladder cells in dish 1 begin to undergo programmed cell death, or apoptosis, when they initially become cancerous. If the cells form sodium-selective pores in their membranes to begin the process of cell death, sodium ions can begin to enter the cells without regulation. What will likely happen to a resting cell membrane potential when sodium enters?
Scientists use a process called Flourescent In-Situ Hybridization, or FISH, to study genetic disorders in humans. FISH is a technique that uses spectrographic analysis to determine the presence or absence, as well as the relative abundance, of genetic material in human cells.
To use FISH, scientists apply fluorescently-labeled bits of DNA of a known color, called probes, to samples of test DNA. These probes anneal to the sample DNA, and scientists can read the colors that result using laboratory equipment. One common use of FISH is to determine the presence of extra DNA in conditions of aneuploidy, a state in which a human cell has an abnormal number of chromosomes. Chromosomes are collections of DNA, the totality of which makes up a cell’s genome. Another typical use is in the study of cancer cells, where scientists use FISH labels to ascertain if genes have moved inappropriately in a cell’s genome.
Using red fluorescent tags, scientists label probe DNA for a gene known to be expressed more heavily in cancer cells than normal cells. They then label a probe for an immediately adjacent DNA sequence with a green fluorescent tag. Both probes are then added to three dishes, shown below. In dish 1 human bladder cells are incubated with the probes, in dish 2 human epithelial cells are incubated, and in dish 3 known non-cancerous cells are used. The relative luminescence observed in regions of interest in all dishes is shown below.
The bladder cells in dish 1 begin to undergo programmed cell death, or apoptosis, when they initially become cancerous. If the cells form sodium-selective pores in their membranes to begin the process of cell death, sodium ions can begin to enter the cells without regulation. What will likely happen to a resting cell membrane potential when sodium enters?
Tap to reveal answer
The pores formed are, according to the question, sodium selective. So it is unlikely that potassium concentration changes will be a major contributor to membrane potential changes. Since sodium is postively charged, and the ions entering are sodium, the inside of the cell will become more positively charged as sodium permeability goes up. We know that sodium will enter and potassium will leave due to the established gradients determined by sodium-potassium ATPase.
The pores formed are, according to the question, sodium selective. So it is unlikely that potassium concentration changes will be a major contributor to membrane potential changes. Since sodium is postively charged, and the ions entering are sodium, the inside of the cell will become more positively charged as sodium permeability goes up. We know that sodium will enter and potassium will leave due to the established gradients determined by sodium-potassium ATPase.
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What is the average resting potential of a nerve cell membrane?
What is the average resting potential of a nerve cell membrane?
Tap to reveal answer
Membrane potential is the difference between the electric potential inside the cell and the electric potential outside the cell. At rest, the membrane potential of most cells (including nerve cells) is between -70mV and -80mV due to the concentration of intracellular and extracellular potassium and sodium ions. The expulsion of sodium ions, in particular, contributes to positive charges outside the cell and lowers the charge inside.
Membrane potential is the difference between the electric potential inside the cell and the electric potential outside the cell. At rest, the membrane potential of most cells (including nerve cells) is between -70mV and -80mV due to the concentration of intracellular and extracellular potassium and sodium ions. The expulsion of sodium ions, in particular, contributes to positive charges outside the cell and lowers the charge inside.
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The side of a plasma membrane receptor will bind to the ligand and the side of the plasma membrane receptor will initiate a cell response.
The side of a plasma membrane receptor will bind to the ligand and the side of the plasma membrane receptor will initiate a cell response.
Tap to reveal answer
In signal transduction, a ligand binds to the extracellular side of the plasma membrane receptor. This initiates a cellular response that is facilitated by the intracellular side. The intracellular region can activate a G protein, bind to an effector, or initiate other cellular responses. These responses often result in a signal cascade that affects transcription factors and alters gene expression.
In signal transduction, a ligand binds to the extracellular side of the plasma membrane receptor. This initiates a cellular response that is facilitated by the intracellular side. The intracellular region can activate a G protein, bind to an effector, or initiate other cellular responses. These responses often result in a signal cascade that affects transcription factors and alters gene expression.
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Which of the following criteria does not help differentiate between prokaryotes and eukaryotes?
Which of the following criteria does not help differentiate between prokaryotes and eukaryotes?
Tap to reveal answer
Cell walls are present in virtually all prokaryotic cells, but are also found in certain eukayotic domains (such as plants and fungi). As such, the presence of a cell wall cannot be used to distinguish between prokaryotic and eukaryotic cells.
Cell walls are present in virtually all prokaryotic cells, but are also found in certain eukayotic domains (such as plants and fungi). As such, the presence of a cell wall cannot be used to distinguish between prokaryotic and eukaryotic cells.
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Prions are the suspected cause of a wide variety of neurodegenerative diseases in mammals. According to prevailing theory, prions are infectious particles made only of protein and found in high concentrations in the brains of infected animals. All mammals produce normal prion protein, PrPC, a transmembrane protein whose function remains unclear.
Infectious prions, PrPRes, induce conformational changes in the existing PrPC proteins according to the following reaction:
PrPC + PrPRes → PrPRes + PrPRes
The PrPRes is then suspected to accumulate in the nervous tissue of infected patients and cause disease. This model of transmission generates replicated proteins, but does so bypassing the standard model of the central dogma of molecular biology. Transcription and translation apparently do not play a role in this replication process.
This theory is a major departure from previously established biological dogma. A scientist decides to test the protein-only theory of prion propagation. He establishes his experiment as follows:
Homogenized brain matter of infected rabbits is injected into the brains of healthy rabbits, as per the following table:
Rabbit 1 and 2: injected with normal saline on days 1 and 2
The above trials serve as controls.
Rabbit 3 and 4: injected with homogenized brain matter on days 1 and 2
The above trials use unmodified brain matter.
Rabbit 5 and 6: injected with irradiated homogenized brain matter on days 1 and 2
The above trials use brain matter that has been irradiated to destroy nucleic acids in the homogenate.
Rabbit 7 and 8: injected with protein-free centrifuged homogenized brain matter on days 1 and 2
The above trials use brain matter that has been centrifuged to generate a protein-free homogenate and a protein-rich homogenate based on molecular weight.
Rabbit 9 and 10: injected with boiled homogenized brain matter on days 1 and 2
The above trials use brain matter that have been boiled to destroy any bacterial contaminants in the homogenate.
Another experiment shows that PrPC reacts with hormones that circulate among nervous tissue. As a transmembrane protein, what kinds of hormones are most likely to interact with PrPC?
I. Peptide hormones
II. Catecholamines
III. Steroid Hormones
Prions are the suspected cause of a wide variety of neurodegenerative diseases in mammals. According to prevailing theory, prions are infectious particles made only of protein and found in high concentrations in the brains of infected animals. All mammals produce normal prion protein, PrPC, a transmembrane protein whose function remains unclear.
Infectious prions, PrPRes, induce conformational changes in the existing PrPC proteins according to the following reaction:
PrPC + PrPRes → PrPRes + PrPRes
The PrPRes is then suspected to accumulate in the nervous tissue of infected patients and cause disease. This model of transmission generates replicated proteins, but does so bypassing the standard model of the central dogma of molecular biology. Transcription and translation apparently do not play a role in this replication process.
This theory is a major departure from previously established biological dogma. A scientist decides to test the protein-only theory of prion propagation. He establishes his experiment as follows:
Homogenized brain matter of infected rabbits is injected into the brains of healthy rabbits, as per the following table:
Rabbit 1 and 2: injected with normal saline on days 1 and 2
The above trials serve as controls.
Rabbit 3 and 4: injected with homogenized brain matter on days 1 and 2
The above trials use unmodified brain matter.
Rabbit 5 and 6: injected with irradiated homogenized brain matter on days 1 and 2
The above trials use brain matter that has been irradiated to destroy nucleic acids in the homogenate.
Rabbit 7 and 8: injected with protein-free centrifuged homogenized brain matter on days 1 and 2
The above trials use brain matter that has been centrifuged to generate a protein-free homogenate and a protein-rich homogenate based on molecular weight.
Rabbit 9 and 10: injected with boiled homogenized brain matter on days 1 and 2
The above trials use brain matter that have been boiled to destroy any bacterial contaminants in the homogenate.
Another experiment shows that PrPC reacts with hormones that circulate among nervous tissue. As a transmembrane protein, what kinds of hormones are most likely to interact with PrPC?
I. Peptide hormones
II. Catecholamines
III. Steroid Hormones
Tap to reveal answer
Students should know that peptide hormones (and catecholamines, but this is not required to answer the question correctly as written here) interact with surface receptors and do not freely go through a membrane. They must interact with the transmembrane surface receptors to initiate a signal transduction cascade. In contrast, steroid hormones can bypass the transmembrance protein receptors by freely diffusing across the memberane, due to their small, nonpolar nature. In this case, only peptide hormones and catecholamines will require the facilitated diffusion mechanism provided by a transmembrane protein.
Students should know that peptide hormones (and catecholamines, but this is not required to answer the question correctly as written here) interact with surface receptors and do not freely go through a membrane. They must interact with the transmembrane surface receptors to initiate a signal transduction cascade. In contrast, steroid hormones can bypass the transmembrance protein receptors by freely diffusing across the memberane, due to their small, nonpolar nature. In this case, only peptide hormones and catecholamines will require the facilitated diffusion mechanism provided by a transmembrane protein.
← Didn't Know|Knew It →
Scientists use a process called Flourescent In-Situ Hybridization, or FISH, to study genetic disorders in humans. FISH is a technique that uses spectrographic analysis to determine the presence or absence, as well as the relative abundance, of genetic material in human cells.
To use FISH, scientists apply fluorescently-labeled bits of DNA of a known color, called probes, to samples of test DNA. These probes anneal to the sample DNA, and scientists can read the colors that result using laboratory equipment. One common use of FISH is to determine the presence of extra DNA in conditions of aneuploidy, a state in which a human cell has an abnormal number of chromosomes. Chromosomes are collections of DNA, the totality of which makes up a cell’s genome. Another typical use is in the study of cancer cells, where scientists use FISH labels to ascertain if genes have moved inappropriately in a cell’s genome.
Using red fluorescent tags, scientists label probe DNA for a gene known to be expressed more heavily in cancer cells than normal cells. They then label a probe for an immediately adjacent DNA sequence with a green fluorescent tag. Both probes are then added to three dishes, shown below. In dish 1 human bladder cells are incubated with the probes, in dish 2 human epithelial cells are incubated, and in dish 3 known non-cancerous cells are used. The relative luminescence observed in regions of interest in all dishes is shown below.
The bladder cells in dish 1 begin to undergo programmed cell death, or apoptosis, when they initially become cancerous. If the cells form sodium-selective pores in their membranes to begin the process of cell death, sodium ions can begin to enter the cells without regulation. What will likely happen to a resting cell membrane potential when sodium enters?
Scientists use a process called Flourescent In-Situ Hybridization, or FISH, to study genetic disorders in humans. FISH is a technique that uses spectrographic analysis to determine the presence or absence, as well as the relative abundance, of genetic material in human cells.
To use FISH, scientists apply fluorescently-labeled bits of DNA of a known color, called probes, to samples of test DNA. These probes anneal to the sample DNA, and scientists can read the colors that result using laboratory equipment. One common use of FISH is to determine the presence of extra DNA in conditions of aneuploidy, a state in which a human cell has an abnormal number of chromosomes. Chromosomes are collections of DNA, the totality of which makes up a cell’s genome. Another typical use is in the study of cancer cells, where scientists use FISH labels to ascertain if genes have moved inappropriately in a cell’s genome.
Using red fluorescent tags, scientists label probe DNA for a gene known to be expressed more heavily in cancer cells than normal cells. They then label a probe for an immediately adjacent DNA sequence with a green fluorescent tag. Both probes are then added to three dishes, shown below. In dish 1 human bladder cells are incubated with the probes, in dish 2 human epithelial cells are incubated, and in dish 3 known non-cancerous cells are used. The relative luminescence observed in regions of interest in all dishes is shown below.
The bladder cells in dish 1 begin to undergo programmed cell death, or apoptosis, when they initially become cancerous. If the cells form sodium-selective pores in their membranes to begin the process of cell death, sodium ions can begin to enter the cells without regulation. What will likely happen to a resting cell membrane potential when sodium enters?
Tap to reveal answer
The pores formed are, according to the question, sodium selective. So it is unlikely that potassium concentration changes will be a major contributor to membrane potential changes. Since sodium is postively charged, and the ions entering are sodium, the inside of the cell will become more positively charged as sodium permeability goes up. We know that sodium will enter and potassium will leave due to the established gradients determined by sodium-potassium ATPase.
The pores formed are, according to the question, sodium selective. So it is unlikely that potassium concentration changes will be a major contributor to membrane potential changes. Since sodium is postively charged, and the ions entering are sodium, the inside of the cell will become more positively charged as sodium permeability goes up. We know that sodium will enter and potassium will leave due to the established gradients determined by sodium-potassium ATPase.
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What is the average resting potential of a nerve cell membrane?
What is the average resting potential of a nerve cell membrane?
Tap to reveal answer
Membrane potential is the difference between the electric potential inside the cell and the electric potential outside the cell. At rest, the membrane potential of most cells (including nerve cells) is between -70mV and -80mV due to the concentration of intracellular and extracellular potassium and sodium ions. The expulsion of sodium ions, in particular, contributes to positive charges outside the cell and lowers the charge inside.
Membrane potential is the difference between the electric potential inside the cell and the electric potential outside the cell. At rest, the membrane potential of most cells (including nerve cells) is between -70mV and -80mV due to the concentration of intracellular and extracellular potassium and sodium ions. The expulsion of sodium ions, in particular, contributes to positive charges outside the cell and lowers the charge inside.
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Which of the following molecules would not require a transport protein to cross the cellular plasma membrane?
Which of the following molecules would not require a transport protein to cross the cellular plasma membrane?
Tap to reveal answer
Nonpolar molecules and very small polar molecules can freely pass through the lipid bilayer, while large, polar molecules and ions need to be aided by transport proteins. Sodium and potassium are both charged ions that would not be able to cross the membrane. Glucose and citrate are too large, and also contain polar regions.
Carbon dioxide is the only answer choice that is both small and nonpolar enough to simply diffuse across the membrane.
Nonpolar molecules and very small polar molecules can freely pass through the lipid bilayer, while large, polar molecules and ions need to be aided by transport proteins. Sodium and potassium are both charged ions that would not be able to cross the membrane. Glucose and citrate are too large, and also contain polar regions.
Carbon dioxide is the only answer choice that is both small and nonpolar enough to simply diffuse across the membrane.
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The side of a plasma membrane receptor will bind to the ligand and the side of the plasma membrane receptor will initiate a cell response.
The side of a plasma membrane receptor will bind to the ligand and the side of the plasma membrane receptor will initiate a cell response.
Tap to reveal answer
In signal transduction, a ligand binds to the extracellular side of the plasma membrane receptor. This initiates a cellular response that is facilitated by the intracellular side. The intracellular region can activate a G protein, bind to an effector, or initiate other cellular responses. These responses often result in a signal cascade that affects transcription factors and alters gene expression.
In signal transduction, a ligand binds to the extracellular side of the plasma membrane receptor. This initiates a cellular response that is facilitated by the intracellular side. The intracellular region can activate a G protein, bind to an effector, or initiate other cellular responses. These responses often result in a signal cascade that affects transcription factors and alters gene expression.
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Engulfment of a foreign pathogen is an example of and engulfment of extracellular fluid is an example of ; both are forms of .
Engulfment of a foreign pathogen is an example of and engulfment of extracellular fluid is an example of ; both are forms of .
Tap to reveal answer
Recall that endocytosis is the process by which solid particles and fluid and transported from the outside to the inside of the cell by the use of vesicles.
When a cell engulfs a foreign pathogen, it creates a vesicle known as a phagosome. The phagosome carries the pathogen within the cell and fuses with a lysosome, which allows hydrolytic enzymes to digest the pathogen. The process of engulfing the pathogen in a vesicle is known as phagocytosis.
A cell can also form a vesicle around fluids in the extracellular space, via the process of pinocytosis. This vesicle can also fuse with lysosomes, allowing the breakdown of small particulates in the vesicle, which can then be used for energy.
Both phagocytosis and pinocytosis are forms of endocytosis.
Recall that endocytosis is the process by which solid particles and fluid and transported from the outside to the inside of the cell by the use of vesicles.
When a cell engulfs a foreign pathogen, it creates a vesicle known as a phagosome. The phagosome carries the pathogen within the cell and fuses with a lysosome, which allows hydrolytic enzymes to digest the pathogen. The process of engulfing the pathogen in a vesicle is known as phagocytosis.
A cell can also form a vesicle around fluids in the extracellular space, via the process of pinocytosis. This vesicle can also fuse with lysosomes, allowing the breakdown of small particulates in the vesicle, which can then be used for energy.
Both phagocytosis and pinocytosis are forms of endocytosis.
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Carbonic anhydrase is a very important enzyme that is utilized by the body. The enzyme catalyzes the following reaction:
A class of drugs that inhibits this enzyme is carbonic anhydrase inhibitors (eg. acetazolamide, brinzolamide, dorzolamide). These drugs are commonly prescribed in patients with glaucoma, hypertension, heart failure, high altitude sickness and for the treatment of basic drugs overdose.
In patients with hypertension, carbonic anhydrase inhibitors will prevent the reabsorption of sodium chloride 
in the proximal tubule of the kidney. When sodium is reabsorbed back into the blood, the molecule creates an electrical force. This electrical force then pulls water along with it into the blood. As more water enters the blood, the blood volume increase. By preventing the reabsorption of sodium, water reabsorption is reduced and the blood pressure decreases.
When mountain climbing, the atmospheric pressure is lowered as the altitude increases. As a result of less oxygen into the lungs, ventilation increases. From the equation above, hyperventilation will result in more 
being expired. Based on Le Chatelier’s principle, the reaction will shift to the left. Since there is more bicarbonate than protons in the body, the blood will become more basic (respiratory alkalosis). To prevent such life threatening result, one would take a carbonic anhydrase inhibitor to prevent the reaction from shifting to the left.
Carbonic anhydrase inhibitors are useful in patients with a drug overdose that is acidic. The lumen of the collecting tubule is nonpolar. Due to the lumen's characteristic, molecules that are also nonpolar and uncharged are able to cross the membrane and re-enter the circulatory system. Since carbonic anhydrase inhibitors alkalize the urine, acidic molecules stay in a charged state.
How will excess intake of a carbonic anhydratase inhibitor affect the blood's osmolarity if not properly regulated by the body?
Carbonic anhydrase is a very important enzyme that is utilized by the body. The enzyme catalyzes the following reaction:
A class of drugs that inhibits this enzyme is carbonic anhydrase inhibitors (eg. acetazolamide, brinzolamide, dorzolamide). These drugs are commonly prescribed in patients with glaucoma, hypertension, heart failure, high altitude sickness and for the treatment of basic drugs overdose.
In patients with hypertension, carbonic anhydrase inhibitors will prevent the reabsorption of sodium chloride
When mountain climbing, the atmospheric pressure is lowered as the altitude increases. As a result of less oxygen into the lungs, ventilation increases. From the equation above, hyperventilation will result in more
Carbonic anhydrase inhibitors are useful in patients with a drug overdose that is acidic. The lumen of the collecting tubule is nonpolar. Due to the lumen's characteristic, molecules that are also nonpolar and uncharged are able to cross the membrane and re-enter the circulatory system. Since carbonic anhydrase inhibitors alkalize the urine, acidic molecules stay in a charged state.
How will excess intake of a carbonic anhydratase inhibitor affect the blood's osmolarity if not properly regulated by the body?
Tap to reveal answer
As mentioned from the passage, carbonic anhydrase inhibitors will prevent water reabsorption at the proximal tubule. As a result, there will be less water in the blood. Osmolarity is a measurement of the amount of solutes divided by the fluid volume. Since the fluid volume will decrease, the osmolarity will increase.
As mentioned from the passage, carbonic anhydrase inhibitors will prevent water reabsorption at the proximal tubule. As a result, there will be less water in the blood. Osmolarity is a measurement of the amount of solutes divided by the fluid volume. Since the fluid volume will decrease, the osmolarity will increase.
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In which of the following structures do actin microfilaments play a crucial role?
I. Contractile ring formed during cytokinesis
II. Sarcomeres
III. Adherens junctions
IV. Eukaryotic flagella
In which of the following structures do actin microfilaments play a crucial role?
I. Contractile ring formed during cytokinesis
II. Sarcomeres
III. Adherens junctions
IV. Eukaryotic flagella
Tap to reveal answer
Eukaryotic flagella are primarily made up of microtubule doublets and singlets organized in a "9+2" manner (two singlets surrounded by nine doublets). Actin microfilaments are not present in flagella.
The contractile ring formed during cytokinesis consists of actin and myosin, and helps separate the two daughter cells to conclude mitosis. Sarcomeres consist of actin and myosin overlaps that are crucial to muscle contraction. Adherens junctions are specialized cell junctions that use the actin cytoskeleton to anchor adjacent cells.
Eukaryotic flagella are primarily made up of microtubule doublets and singlets organized in a "9+2" manner (two singlets surrounded by nine doublets). Actin microfilaments are not present in flagella.
The contractile ring formed during cytokinesis consists of actin and myosin, and helps separate the two daughter cells to conclude mitosis. Sarcomeres consist of actin and myosin overlaps that are crucial to muscle contraction. Adherens junctions are specialized cell junctions that use the actin cytoskeleton to anchor adjacent cells.
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What is the difference between cytosolic ribosomes and ribosomes on the rough endoplasmic reticulum (RER)?
What is the difference between cytosolic ribosomes and ribosomes on the rough endoplasmic reticulum (RER)?
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While both types of ribosomes are used to make proteins, the difference between them has to do with the fate of the proteins. Cytosolic ribosomes make proteins for the cytosol, which rough endoplasmic reticulum ribosomes make them to be bound in membranes, or to be excreted from the cell in vesicles (exocytosis). Both types of ribosmes require a peptidyl transferase to elongate the peptide chain during protein synthesis.
While both types of ribosomes are used to make proteins, the difference between them has to do with the fate of the proteins. Cytosolic ribosomes make proteins for the cytosol, which rough endoplasmic reticulum ribosomes make them to be bound in membranes, or to be excreted from the cell in vesicles (exocytosis). Both types of ribosmes require a peptidyl transferase to elongate the peptide chain during protein synthesis.
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Scientists identify a mutation in an isolated community in central Africa that prevents individuals from detoxifying potentially harmful organic molecules, leading to a high percentage of people who become very ill after consuming alcohol. What cellular organelle does this mutation most likely affect the most?
Scientists identify a mutation in an isolated community in central Africa that prevents individuals from detoxifying potentially harmful organic molecules, leading to a high percentage of people who become very ill after consuming alcohol. What cellular organelle does this mutation most likely affect the most?
Tap to reveal answer
The smooth endoplasmic reticulum functions in drug and alcohol detoxification. A common incorrect answer chosen here is the lysozome, which digests food, bacteria, viruses, and damaged organelles or cellular structures.
The smooth endoplasmic reticulum functions in drug and alcohol detoxification. A common incorrect answer chosen here is the lysozome, which digests food, bacteria, viruses, and damaged organelles or cellular structures.
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Scientists use a process called Flourescent In-Situ Hybridization, or FISH, to study genetic disorders in humans. FISH is a technique that uses spectrographic analysis to determine the presence or absence, as well as the relative abundance, of genetic material in human cells.
To use FISH, scientists apply fluorescently-labeled bits of DNA of a known color, called probes, to samples of test DNA. These probes anneal to the sample DNA, and scientists can read the colors that result using laboratory equipment. One common use of FISH is to determine the presence of extra DNA in conditions of aneuploidy, a state in which a human cell has an abnormal number of chromosomes. Chromosomes are collections of DNA, the totality of which makes up a cell’s genome. Another typical use is in the study of cancer cells, where scientists use FISH labels to ascertain if genes have moved inappropriately in a cell’s genome.
Using red fluorescent tags, scientists label probe DNA for a gene known to be expressed more heavily in cancer cells than normal cells. They then label a probe for an immediately adjacent DNA sequence with a green fluorescent tag. Both probes are then added to three dishes, shown below. In dish 1 human bladder cells are incubated with the probes, in dish 2 human epithelial cells are incubated, and in dish 3 known non-cancerous cells are used. The relative luminescence observed in regions of interest in all dishes is shown below.
A scientist discovers that there is a class of proteins called tumor suppressors. These proteins are present in the cytosol of almost all human cells, and serve to downregulate cell division by preventing entry into key parts of the cell cycle. Where are these proteins most likely synthesized?
Scientists use a process called Flourescent In-Situ Hybridization, or FISH, to study genetic disorders in humans. FISH is a technique that uses spectrographic analysis to determine the presence or absence, as well as the relative abundance, of genetic material in human cells.
To use FISH, scientists apply fluorescently-labeled bits of DNA of a known color, called probes, to samples of test DNA. These probes anneal to the sample DNA, and scientists can read the colors that result using laboratory equipment. One common use of FISH is to determine the presence of extra DNA in conditions of aneuploidy, a state in which a human cell has an abnormal number of chromosomes. Chromosomes are collections of DNA, the totality of which makes up a cell’s genome. Another typical use is in the study of cancer cells, where scientists use FISH labels to ascertain if genes have moved inappropriately in a cell’s genome.
Using red fluorescent tags, scientists label probe DNA for a gene known to be expressed more heavily in cancer cells than normal cells. They then label a probe for an immediately adjacent DNA sequence with a green fluorescent tag. Both probes are then added to three dishes, shown below. In dish 1 human bladder cells are incubated with the probes, in dish 2 human epithelial cells are incubated, and in dish 3 known non-cancerous cells are used. The relative luminescence observed in regions of interest in all dishes is shown below.
A scientist discovers that there is a class of proteins called tumor suppressors. These proteins are present in the cytosol of almost all human cells, and serve to downregulate cell division by preventing entry into key parts of the cell cycle. Where are these proteins most likely synthesized?
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Tumor suppressors, as defined in the question, are proteins. Proteins are synthesized by ribosomes. While the rough endoplasmic reticulum contains ribosomes, its function is related to the synthesis of transmembrane and extra-cellular proteins. Cytosolic ribosomes will be responsible for synthesis of proteins that remain in the cell.
Tumor suppressors, as defined in the question, are proteins. Proteins are synthesized by ribosomes. While the rough endoplasmic reticulum contains ribosomes, its function is related to the synthesis of transmembrane and extra-cellular proteins. Cytosolic ribosomes will be responsible for synthesis of proteins that remain in the cell.
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Which of the following cellular components synthesizes lipids of the plasma membrane?
Which of the following cellular components synthesizes lipids of the plasma membrane?
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Lipids that are usually used for the cell membrane are created in the smooth endoplasmic reticulum. The rough endoplasmic reticulum and ribosomes are involved in protein production. The mitochondria are essential in producing ATP.
Lipids that are usually used for the cell membrane are created in the smooth endoplasmic reticulum. The rough endoplasmic reticulum and ribosomes are involved in protein production. The mitochondria are essential in producing ATP.
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In 2013, scientists linked a cellular response called the unfolded protein response (UPR) to a series of neurodegenerative diseases, including such major health issues as Parkinson’s and Alzheimer’s Disease. According to their work, the unfolded protein response is a reduction in translation as a result of a series of enzymes that modify a translation initiation factor, eIF2, as below:
In the above sequence, the unfolded protein sensor binds to unfolded protein, such as the pathogenic amyloid-beta found in the brains of Alzheimer’s Disease patients. This sensor then phosphorylates PERK, or protein kinase RNA-like endoplasmic reticulum kinase. This leads to downstream effects on eIF2, inhibition of which represses translation. It is thought that symptoms of neurodegenerative disease may be a result of this reduced translation.
Regarding unfolded proteins discussed in the passage, which organelle is likely to be the site of initial protein folding in normal cells?
In 2013, scientists linked a cellular response called the unfolded protein response (UPR) to a series of neurodegenerative diseases, including such major health issues as Parkinson’s and Alzheimer’s Disease. According to their work, the unfolded protein response is a reduction in translation as a result of a series of enzymes that modify a translation initiation factor, eIF2, as below:
In the above sequence, the unfolded protein sensor binds to unfolded protein, such as the pathogenic amyloid-beta found in the brains of Alzheimer’s Disease patients. This sensor then phosphorylates PERK, or protein kinase RNA-like endoplasmic reticulum kinase. This leads to downstream effects on eIF2, inhibition of which represses translation. It is thought that symptoms of neurodegenerative disease may be a result of this reduced translation.
Regarding unfolded proteins discussed in the passage, which organelle is likely to be the site of initial protein folding in normal cells?
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Protein folding takes place in the endoplasmic reticulum, typically coinciding with the translation by bound ribosomes of the rough endoplasmic reticulum. Further modification can take place in the Golgi. Note that ribosomes in the cytosol or on the rough endoplasmic reticulum may translate a protein, but the protein folding will occur in the endoplasmic reticulum.
Protein folding takes place in the endoplasmic reticulum, typically coinciding with the translation by bound ribosomes of the rough endoplasmic reticulum. Further modification can take place in the Golgi. Note that ribosomes in the cytosol or on the rough endoplasmic reticulum may translate a protein, but the protein folding will occur in the endoplasmic reticulum.
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The liver is one of the major sites for drug metabolism and detoxification. Which organelle would you expect to play an important role in this process?
The liver is one of the major sites for drug metabolism and detoxification. Which organelle would you expect to play an important role in this process?
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One of the major functions of the smooth endoplasmic reticulum is drug metabolism. In the liver, the cellular smooth endoplasmic reticulum serves as the primary site of drug and alcohol detoxifiction. This organelle is present (and active) in cells throughout the body, but plays the most impactful role in the cells of the liver. While lysosomes are responsible for clearing cellular debris, they commonly digest pathogens and microbes rather than chemical contaminants, like drugs or alcohol.
One of the major functions of the smooth endoplasmic reticulum is drug metabolism. In the liver, the cellular smooth endoplasmic reticulum serves as the primary site of drug and alcohol detoxifiction. This organelle is present (and active) in cells throughout the body, but plays the most impactful role in the cells of the liver. While lysosomes are responsible for clearing cellular debris, they commonly digest pathogens and microbes rather than chemical contaminants, like drugs or alcohol.
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