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Questions and Answers
Which of the following cell structures exhibits selective permeability between a cell and its external environment?
Which of the following cell structures exhibits selective permeability between a cell and its external environment?
Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?
Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?
The plasma membrane is referred to as a fluid mosaic structure. Which of the following statements about that model is true?
The plasma membrane is referred to as a fluid mosaic structure. Which of the following statements about that model is true?
Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found?
Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found?
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Which of the following functional processes is not a consequence of the association of proteins with biological membranes?
Which of the following functional processes is not a consequence of the association of proteins with biological membranes?
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Which of the following statements concerning carbohydrates associated with the plasma membrane is correct?
Which of the following statements concerning carbohydrates associated with the plasma membrane is correct?
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Where in the membrane would carbohydrates most likely be found?
Where in the membrane would carbohydrates most likely be found?
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Which statements about the sidedness of the plasma membrane is/are correct?
Which statements about the sidedness of the plasma membrane is/are correct?
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Which of the following molecules is most likely to passively diffuse across the plasma membrane?
Which of the following molecules is most likely to passively diffuse across the plasma membrane?
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Which of the following would be LEAST likely to diffuse through a plasma membrane without the help of a transport protein?
Which of the following would be LEAST likely to diffuse through a plasma membrane without the help of a transport protein?
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Which of the following structural arrangements of the components in biological membranes is most consistent with the membrane's property of selective permeability?
Which of the following structural arrangements of the components in biological membranes is most consistent with the membrane's property of selective permeability?
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Which of the following statements about passive transport is correct?
Which of the following statements about passive transport is correct?
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Oxygen will diffuse more rapidly into cell __________ because __________.
Oxygen will diffuse more rapidly into cell __________ because __________.
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Diffusion is a passive process of a substance across a membrane with energy investment.
Diffusion is a passive process of a substance across a membrane with energy investment.
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To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?
To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?
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A single plant cell is placed in an isotonic solution. Salt is then added to the solution. Which of the following would occur as a result of the salt addition?
A single plant cell is placed in an isotonic solution. Salt is then added to the solution. Which of the following would occur as a result of the salt addition?
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Which of these statements describes some aspect of facilitated diffusion?
Which of these statements describes some aspect of facilitated diffusion?
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Facilitated diffusion requires the hydrolysis of ATP.
Facilitated diffusion requires the hydrolysis of ATP.
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Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions?
Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions?
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How does the preservation of green olives in brine, a 30% salt solution, prevent microorganisms from growing in the olives?
How does the preservation of green olives in brine, a 30% salt solution, prevent microorganisms from growing in the olives?
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Based on the information that active transport requires energy and can generate voltages across membranes, which of the following statements is true?
Based on the information that active transport requires energy and can generate voltages across membranes, which of the following statements is true?
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Which of the following is a correct difference between active transport and facilitated diffusion?
Which of the following is a correct difference between active transport and facilitated diffusion?
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Which of the following best describes a mechanism by which Ca2+ enters the cell?
Which of the following best describes a mechanism by which Ca2+ enters the cell?
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Which of the following correctly describes a general property of all electrogenic pumps?
Which of the following correctly describes a general property of all electrogenic pumps?
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Which of the following statements about cotransport of solutes across a membrane is correct?
Which of the following statements about cotransport of solutes across a membrane is correct?
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Consider the transport of protons and sucrose into a plant cell by the sucrose-proton cotransport protein. Why, in the absence of sucrose, don't protons move back into the cell through the sucrose-proton cotransport protein?
Consider the transport of protons and sucrose into a plant cell by the sucrose-proton cotransport protein. Why, in the absence of sucrose, don't protons move back into the cell through the sucrose-proton cotransport protein?
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Which of the following enables a cell to pick up and concentrate a specific kind of molecule?
Which of the following enables a cell to pick up and concentrate a specific kind of molecule?
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Which of the following processes and organelles account for the replacement of lipids and proteins lost from the plasma membrane?
Which of the following processes and organelles account for the replacement of lipids and proteins lost from the plasma membrane?
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How do large protein molecules, such as antibodies, enter the cells lining the baby's digestive tract?
How do large protein molecules, such as antibodies, enter the cells lining the baby's digestive tract?
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Which of the following pairs correctly matches a membrane transport process to its primary function?
Which of the following pairs correctly matches a membrane transport process to its primary function?
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When a platelet contacts a damaged blood vessel, it is stimulated to release thromboxane A2. Thromboxane A2 in turn stimulates vascular spasm and attracts additional platelets to the injured site. In this example thromboxane A2 is acting as a __________.
When a platelet contacts a damaged blood vessel, it is stimulated to release thromboxane A2. Thromboxane A2 in turn stimulates vascular spasm and attracts additional platelets to the injured site. In this example thromboxane A2 is acting as a __________.
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Early work on signal transduction and glycogen metabolism by Sutherland indicated that __________.
Early work on signal transduction and glycogen metabolism by Sutherland indicated that __________.
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Testosterone and estrogen are lipid-soluble signal molecules that cross the plasma membrane by simple diffusion. If these molecules can enter all cells, why do only specific cells respond to their presence? __________.
Testosterone and estrogen are lipid-soluble signal molecules that cross the plasma membrane by simple diffusion. If these molecules can enter all cells, why do only specific cells respond to their presence? __________.
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Steroid hormones can enter a cell by simple diffusion. Therefore, steroids __________.
Steroid hormones can enter a cell by simple diffusion. Therefore, steroids __________.
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Steroid hormones can enter a cell by simple diffusion. Therefore steroids __________.
Steroid hormones can enter a cell by simple diffusion. Therefore steroids __________.
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Receptors for signal molecules __________.
Receptors for signal molecules __________.
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Testosterone does NOT affect all cells of the body because __________.
Testosterone does NOT affect all cells of the body because __________.
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Nitric oxide is unusual among animal signal molecules in that it __________.
Nitric oxide is unusual among animal signal molecules in that it __________.
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A G protein is active when __________.
A G protein is active when __________.
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What event would activate a G protein? __________.
What event would activate a G protein? __________.
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Ras, a small G protein located at the plasma membrane, is often mutated in different types of cancer. Ras normally signals to a cell that it should divide. Cancer cells divide uncontrollably. Which of the following changes to Ras would you expect to see in a cancer cell that has mutated Ras present?
Ras, a small G protein located at the plasma membrane, is often mutated in different types of cancer. Ras normally signals to a cell that it should divide. Cancer cells divide uncontrollably. Which of the following changes to Ras would you expect to see in a cancer cell that has mutated Ras present?
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The cellular response of a signal pathway that terminates at a transcription factor would be __________.
The cellular response of a signal pathway that terminates at a transcription factor would be __________.
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What did Sutherland discover about glycogen metabolism in liver cells? __________.
What did Sutherland discover about glycogen metabolism in liver cells? __________.
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The general name for an enzyme that transfers phosphate groups from ATP to a protein is __________.
The general name for an enzyme that transfers phosphate groups from ATP to a protein is __________.
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If ATPgammaS is a form of ATP that cannot be hydrolyzed by enzymes. If this compound was introduced to cells so that it replaced the normal ATP present in the cell, which of the following would you predict? __________.
If ATPgammaS is a form of ATP that cannot be hydrolyzed by enzymes. If this compound was introduced to cells so that it replaced the normal ATP present in the cell, which of the following would you predict? __________.
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What does the addition of a phosphate group do to a protein? __________.
What does the addition of a phosphate group do to a protein? __________.
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The source of phosphate for a phosphorylation cascade is __________.
The source of phosphate for a phosphorylation cascade is __________.
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Second messengers tend to be water-soluble and small. This accounts for their ability to __________.
Second messengers tend to be water-soluble and small. This accounts for their ability to __________.
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CAMP usually directly activates __________.
CAMP usually directly activates __________.
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A mutation in the active site of adenylyl cyclase that inactivates it would most likely lead to __________.
A mutation in the active site of adenylyl cyclase that inactivates it would most likely lead to __________.
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In eukaryotic cells, which of the following is a second messenger that is produced as a response to an external signal such as a hormone?
In eukaryotic cells, which of the following is a second messenger that is produced as a response to an external signal such as a hormone?
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Study Notes
Plasma Membrane and Selective Permeability
- The plasma membrane features selective permeability, regulating the passage of substances between the cell and its environment.
- Phospholipids create a selectively permeable layer, essential for membrane structure and function.
- The fluid mosaic model describes the plasma membrane's dynamic nature due to phospholipid movement and the embedded proteins that contribute to its mosaic appearance.
Membrane Composition and Structure
- Cholesterol is located between phospholipid molecules, aiding membrane fluidity.
- Membrane carbohydrates primarily serve for cell-cell recognition and are situated on the external surface of the membrane.
- The asymmetrical distribution of membrane components is established during membrane assembly, influencing the specific orientation of integral proteins.
Molecular Transport Mechanisms
- Small nonpolar molecules like carbon dioxide can easily passively diffuse across the plasma membrane.
- Large polar molecules require transport proteins to diffuse through the membrane effectively.
- The arrangement of proteins within two layers of phospholipids enhances selective permeability.
Passive and Active Transport
- Passive transport allows solutes to move down their concentration gradients without energy expenditure.
- Oxygen diffuses more rapidly into actively respiring cells, where the concentration gradient is steeper.
- Osmosis causes plant cells to lose water in hypertonic solutions, leading to potential plasmolysis.
Facilitated Diffusion and Ion Transport
- Facilitated diffusion utilizes channel or transport proteins to assist solute movement, not requiring ATP.
- Red blood cells shrink when placed in a hypertonic sucrose solution due to osmosis.
- The sodium/potassium pump hydrolyzes ATP, generating a charge difference across the membrane.
Signal Reception and Transduction
- Endocytosis mechanisms enable cells to concentrate specific molecules, while receptor-mediated endocytosis is one method to uptake large proteins like antibodies.
- Specific cells respond to steroid hormones because they possess the necessary intracellular receptors.
- Activated G proteins yield a cellular response upon binding GTP, which replaces GDP.
Cellular Responses and Enzyme Activity
- A phosphorylation cascade is critical in signaling pathways, utilizing ATP as the phosphate source.
- The addition of a phosphate group can modulate the activity of proteins, either activating or deactivating them.
- cAMP functions as a second messenger, typically activating protein kinase A.
Cancer Signaling and Enzymatic Functions
- Mutations in signaling proteins, like Ras, can lead to uncontrolled cell division, a hallmark of cancer.
- Protein kinases transfer phosphate groups from ATP to proteins, playing roles in various signaling pathways.
- Adenylyl cyclase activation facilitates increased kinase activity, which would be disrupted by mutations that inactivate it.
Summary of Key Functions
- Membrane transport processes include pinocytosis, active transport (against gradients), and facilitated diffusion, facilitating various cellular functions.
- The interplay of hormones, receptors, and intracellular signals orchestrates complex responses within cells, highlighting the intricate nature of cellular communication and metabolism.
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Description
Test your knowledge with this quiz focused on Chapter 5 of biology, covering cell structures and the plasma membrane. Determine your understanding of key concepts such as selective permeability and the role of phospholipids in biological membranes.
