Podcast
Questions and Answers
What property of phospholipids allows them to spontaneously form bilayers in aqueous solutions?
What property of phospholipids allows them to spontaneously form bilayers in aqueous solutions?
- Their high molecular weight.
- Their amphipathic nature. (correct)
- The presence of cholesterol within their structure.
- Their ability to form covalent bonds with water molecules.
How does cholesterol contribute to the fluidity of the cell membrane at low temperatures?
How does cholesterol contribute to the fluidity of the cell membrane at low temperatures?
- By forming crystalline structures that enhance fluidity.
- By increasing the van der Waals forces between phospholipid tails.
- By disrupting the packing of phospholipid molecules. (correct)
- By solidifying the membrane to prevent movement.
Which characteristic of cholesterol helps to maintain membrane stability at high temperatures?
Which characteristic of cholesterol helps to maintain membrane stability at high temperatures?
- Its polar head group readily interacts with water.
- Its ability to increase the space between phospholipid molecules.
- Its non-polar hydrocarbon tail enhances fluidity.
- Its planar steroid ring structure. (correct)
What is the primary reason for the high proportion of proteins in a typical cell membrane?
What is the primary reason for the high proportion of proteins in a typical cell membrane?
How does the specialization of the cell membrane in a nerve cell exemplify the relationship between structure and function?
How does the specialization of the cell membrane in a nerve cell exemplify the relationship between structure and function?
What is the primary consequence of spectrin deficiency in hereditary spherocytosis?
What is the primary consequence of spectrin deficiency in hereditary spherocytosis?
Which component of the cell membrane is often associated with carbohydrates to form the glycocalyx?
Which component of the cell membrane is often associated with carbohydrates to form the glycocalyx?
What type of bonds primarily maintain the interaction between cholesterol and neighboring phospholipid molecules in the cell membrane?
What type of bonds primarily maintain the interaction between cholesterol and neighboring phospholipid molecules in the cell membrane?
How does the presence of a high proportion of proteins in the mitochondrial membrane relate to its function?
How does the presence of a high proportion of proteins in the mitochondrial membrane relate to its function?
In hereditary spherocytosis, defects in which protein, other than spectrin, can lead to the same condition?
In hereditary spherocytosis, defects in which protein, other than spectrin, can lead to the same condition?
Which of the following is NOT a typical sign or symptom associated with hereditary spherocytosis?
Which of the following is NOT a typical sign or symptom associated with hereditary spherocytosis?
How does the fluidity of the cell membrane affect its function?
How does the fluidity of the cell membrane affect its function?
What role do van der Waals forces play in the structure of the cell membrane?
What role do van der Waals forces play in the structure of the cell membrane?
How do electrostatic and hydrogen bonds contribute to the stability of the cell membrane?
How do electrostatic and hydrogen bonds contribute to the stability of the cell membrane?
What distinguishes integral membrane proteins from peripheral membrane proteins?
What distinguishes integral membrane proteins from peripheral membrane proteins?
What is a key function of the cell membrane in maintaining cellular homeostasis?
What is a key function of the cell membrane in maintaining cellular homeostasis?
Which structural component is unique to cholesterol and contributes to its function in the cell membrane?
Which structural component is unique to cholesterol and contributes to its function in the cell membrane?
How would a decrease in membrane cholesterol affect a cell's response to changing temperatures?
How would a decrease in membrane cholesterol affect a cell's response to changing temperatures?
What is the significance of the amphipathic nature of phospholipids in the context of cell membrane formation?
What is the significance of the amphipathic nature of phospholipids in the context of cell membrane formation?
Which cellular process would be most directly affected by a mutation that disrupts the function of integral membrane proteins?
Which cellular process would be most directly affected by a mutation that disrupts the function of integral membrane proteins?
How does the glycocalyx contribute to cell function and identity?
How does the glycocalyx contribute to cell function and identity?
What adaptation would you expect to see in the cell membranes of organisms living in extremely cold environments?
What adaptation would you expect to see in the cell membranes of organisms living in extremely cold environments?
How does hereditary spherocytosis affect the lifespan of red blood cells?
How does hereditary spherocytosis affect the lifespan of red blood cells?
Which of the following is the most accurate description of the arrangement of phospholipids in a cell membrane?
Which of the following is the most accurate description of the arrangement of phospholipids in a cell membrane?
What would be the most likely effect on a cell if it were treated with a drug that inhibits cholesterol synthesis?
What would be the most likely effect on a cell if it were treated with a drug that inhibits cholesterol synthesis?
How do cells in different tissues or locations within an organism maintain specialized membrane functions?
How do cells in different tissues or locations within an organism maintain specialized membrane functions?
How does the presence of cholesterol affect the permeability of the cell membrane?
How does the presence of cholesterol affect the permeability of the cell membrane?
What is the most likely outcome of complete disruption of van der Waals forces between phospholipid tails in a cell membrane?
What is the most likely outcome of complete disruption of van der Waals forces between phospholipid tails in a cell membrane?
What is the primary function of proteins in the cell membrane?
What is the primary function of proteins in the cell membrane?
Flashcards
Glycocalyx
Glycocalyx
Outer carbohydrate coat surrounding a cell, formed by carbohydrates attached to proteins and lipids on the cell membrane's exterior.
Amphipathic molecules
Amphipathic molecules
Molecules with both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts.
Phospholipid bilayer
Phospholipid bilayer
Arrangement formed by phospholipids in water, with hydrophilic heads facing out and hydrophobic tails facing in.
Cholesterol in cell membrane
Cholesterol in cell membrane
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Integral membrane proteins
Integral membrane proteins
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Peripheral membrane proteins
Peripheral membrane proteins
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Function of cell membranes
Function of cell membranes
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Hereditary spherocytosis
Hereditary spherocytosis
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Study Notes
- Cell membranes separate the intracellular and extracellular environments of the cell.
- Lipids, proteins, and carbohydrates are the key components of cell membranes.
- A carbohydrate coat called the glycocalyx is often found attached to proteins or lipids on the outside of the cell membrane.
Phospholipids
- Consist of a head molecule, a phosphate molecule, a glycerol, and two fatty acid chains.
- Phospholipid molecules are amphipathic, with both hydrophilic and hydrophobic properties.
- They spontaneously form bilayers in water, with head groups facing out and tail groups facing in.
- Van der Waal forces act between the fatty acid tails, and electrostatic and hydrogen bonds form between hydrophilic groups and water.
Cholesterol
- Vital for cell function and a major constituent of the cell membrane.
- It has a polar head, a planar steroid ring, and a non-polar hydrocarbon tail.
- It helps maintain cell membrane stability and fluidity at varying temperatures.
- At low temperatures, it reduces phospholipid packing, maintaining a fluid phase.
- At high temperatures, it prevents crystalline structures, making the membrane less fluid.
Proteins
- Proteins typically constitute about 60% of a cell membrane.
- Membrane protein functions include:
- Acting as receptors, pores, or enzymes.
- Involvement in cell signalling.
- Transportation.
- More active cells or organelles like mitochondria tend to contain more proteins.
- Proteins can be deeply embedded within the bilayer (integral) or associated with the surface of the cell (peripheral).
Functions of Cell Membranes
- Vital for the normal functioning of all the cells.
- Their main functions include:
- Separation of the intracellular and extracellular environments.
- Regulation of transport.
- Communication.
- Different parts of the membrane have different functions and specialized structures.
- The cell membrane in the axon of a nerve is specialized for electrical conduction, while the end of the nerve is specialized for synapsing.
Hereditary Spherocytosis
- A condition in which spectrin, a peripheral cytoskeletal protein, is depleted by 40-80%.
- There are both autosomal dominant and recessive forms of the condition.
- Lack of spectrin impairs erythrocytes' ability to maintain their biconcave structure, causing them to assume a spherical shape.
- This decreases their ability to travel through the microvasculature, leading to increased erythrocyte lysis.
- Defects in ankyrin, band 3, and protein 4.2 can also cause spherocytosis, but spectrin deficiency is the most significant.
- Signs and symptoms include:
- Anemia.
- Jaundice.
- Splenomegaly.
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