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Questions and Answers
What is the primary function of cholesterol in the cell membrane?
Which biomolecule is found only on the exterior of the cell membrane?
What is the percentage of proteins in the cell membrane?
What is the function of channel proteins in the cell membrane?
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What is the function of the glycocalyx on the cell membrane?
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What is the primary function of the cell membrane?
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What is the characteristic of phospholipids that allows them to form a bilayer?
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What is the function of integral proteins in the cell membrane?
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What is the result of cholesterol's presence in the cell membrane at high temperatures?
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Which of the following is a function of the cell membrane?
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What is the approximate percentage of phospholipids in the cell membrane?
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What is the role of carbohydrates in the cell membrane?
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Which of the following biomolecules is not embedded in the phospholipid bilayer?
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What is the significance of the cell membrane's role in organ transplants and blood transfusions?
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What is the main function of transport proteins in the cell membrane?
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What is the result of the presence of phospholipids in the cell membrane?
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Study Notes
History of the Cell Membrane
- Garde Nicholson and Jonathan Singer proposed the fluid mosaic model in 1932
Composition of the Cell Membrane
- Phospholipids (40%): found throughout the cell membrane
- Proteins (50%): embedded in the phospholipid bilayer, can be found in the peripheral or interior of the membrane
- Carbohydrates (10%): found only on the exterior of the cell membrane
- Cholesterol: attached to phospholipids
Functions of Each Biomolecule
- Phospholipids:
- Have a polar, hydrophilic head and a non-polar, hydrophobic tail
- Form a bilayer with hydrophilic heads facing outward and inward, and hydrophobic tails facing inward
- Allow water to pass through, but not other substances
- Cholesterol:
- Helps maintain fluidity of the membrane at different temperatures
- Increases fluidity at low temperatures, decreases fluidity at high temperatures
- Proteins:
- Integral proteins: span the entire membrane
- Peripheral proteins: found on the periphery of the membrane
- Two types of integral proteins:
- Channel proteins: form a channel for molecules to pass through
- Transport proteins: change conformation to transport molecules across the membrane
- Carbohydrates:
- Form a glycocalyx (glycoproteins and glycolipids) on the exterior of the cell membrane
- Help the cell recognize its surroundings and interact with other cells and molecules
Functions of the Cell Membrane
- Protects the cell and its organelles
- Regulates transport of substances into and out of the cell
- Helps the cell recognize and interact with its surroundings
- Important for compatibility in organ transplants and blood transfusions
History of the Cell Membrane
- Garde Nicholson and Jonathan Singer proposed the fluid mosaic model in 1972 (not 1932)
Composition of the Cell Membrane
- Phospholipids make up 40% of the cell membrane and are found throughout
- Proteins account for 50% of the cell membrane and are embedded in the phospholipid bilayer
- Carbohydrates make up 10% of the cell membrane and are only found on the exterior
- Cholesterol is attached to phospholipids
Phospholipids
- Have a polar, hydrophilic head and a non-polar, hydrophobic tail
- Form a bilayer with hydrophilic heads facing outward and inward, and hydrophobic tails facing inward
- Allow water to pass through, but not other substances
Cholesterol
- Helps maintain fluidity of the membrane at different temperatures
- Increases fluidity at low temperatures, decreases fluidity at high temperatures
Proteins
- Integral proteins span the entire membrane
- Peripheral proteins are found on the periphery of the membrane
- There are two types of integral proteins:
- Channel proteins form a channel for molecules to pass through
- Transport proteins change conformation to transport molecules across the membrane
Carbohydrates
- Form a glycocalyx (glycoproteins and glycolipids) on the exterior of the cell membrane
- Help the cell recognize its surroundings and interact with other cells and molecules
Functions of the Cell Membrane
- Protects the cell and its organelles
- Regulates transport of substances into and out of the cell
- Helps the cell recognize and interact with its surroundings
- Important for compatibility in organ transplants and blood transfusions
History of the Cell Membrane
- Garde Nicholson and Jonathan Singer proposed the fluid mosaic model in 1972 (not 1932)
Composition of the Cell Membrane
- Phospholipids make up 40% of the cell membrane and are found throughout
- Proteins account for 50% of the cell membrane and are embedded in the phospholipid bilayer
- Carbohydrates make up 10% of the cell membrane and are only found on the exterior
- Cholesterol is attached to phospholipids
Phospholipids
- Have a polar, hydrophilic head and a non-polar, hydrophobic tail
- Form a bilayer with hydrophilic heads facing outward and inward, and hydrophobic tails facing inward
- Allow water to pass through, but not other substances
Cholesterol
- Helps maintain fluidity of the membrane at different temperatures
- Increases fluidity at low temperatures, decreases fluidity at high temperatures
Proteins
- Integral proteins span the entire membrane
- Peripheral proteins are found on the periphery of the membrane
- There are two types of integral proteins:
- Channel proteins form a channel for molecules to pass through
- Transport proteins change conformation to transport molecules across the membrane
Carbohydrates
- Form a glycocalyx (glycoproteins and glycolipids) on the exterior of the cell membrane
- Help the cell recognize its surroundings and interact with other cells and molecules
Functions of the Cell Membrane
- Protects the cell and its organelles
- Regulates transport of substances into and out of the cell
- Helps the cell recognize and interact with its surroundings
- Important for compatibility in organ transplants and blood transfusions
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Description
Explore the composition and functions of the cell membrane, including phospholipids, proteins, carbohydrates, and cholesterol, and learn about the fluid mosaic model.
