Podcast
Questions and Answers
What is the main characteristic of the plasma membrane's selectivity?
What is the main characteristic of the plasma membrane's selectivity?
- It allows all substances to pass freely.
- It only allows water and small ions to enter the cell.
- It prevents any substances from crossing.
- It selectively permits some substances to cross more easily than others. (correct)
What is one of the primary functions of the plasma membrane?
What is one of the primary functions of the plasma membrane?
- To provide structural rigidity to the cell.
- To facilitate intracellular communication.
- To control what enters and exits the cell. (correct)
- To generate energy for the cell.
What is the approximate thickness of the plasma membrane?
What is the approximate thickness of the plasma membrane?
- 20 nm
- 5 nm
- 12 nm
- 8 nm (correct)
What role does the plasma membrane play in the protection of the cell?
What role does the plasma membrane play in the protection of the cell?
What internal balance does the plasma membrane help maintain?
What internal balance does the plasma membrane help maintain?
What is the primary component of cell membranes?
What is the primary component of cell membranes?
What characteristic do amphipathic molecules possess?
What characteristic do amphipathic molecules possess?
How does cholesterol affect membrane fluidity at warm temperatures?
How does cholesterol affect membrane fluidity at warm temperatures?
Which term describes the selective ability of the cell membrane?
Which term describes the selective ability of the cell membrane?
What structure of phospholipids faces the internal environment of the cell?
What structure of phospholipids faces the internal environment of the cell?
What is the overall shape of the cell membrane described as?
What is the overall shape of the cell membrane described as?
What is the primary role of the proteins in the cell membrane?
What is the primary role of the proteins in the cell membrane?
What is the polar characteristic of the phosphate head of phospholipids?
What is the polar characteristic of the phosphate head of phospholipids?
What role does cholesterol play in the cell membrane at lower temperatures?
What role does cholesterol play in the cell membrane at lower temperatures?
How do cells respond to changes in temperature regarding membrane lipid concentration?
How do cells respond to changes in temperature regarding membrane lipid concentration?
Which statement is true about integral proteins?
Which statement is true about integral proteins?
What characterizes peripheral proteins in the cell membrane?
What characterizes peripheral proteins in the cell membrane?
What is the fluidity of the membrane at higher temperatures?
What is the fluidity of the membrane at higher temperatures?
What is the primary function of membrane proteins?
What is the primary function of membrane proteins?
Which feature is NOT characteristic of integral proteins?
Which feature is NOT characteristic of integral proteins?
What is the overall structure of the cell membrane commonly described as?
What is the overall structure of the cell membrane commonly described as?
Flashcards
Plasma Membrane Function
Plasma Membrane Function
The plasma membrane controls the passage of substances into and out of the cell to maintain internal balance.
Plasma Membrane Structure
Plasma Membrane Structure
The plasma membrane is made up of lipids, proteins, and other components.
Cell Membrane Introduction
Cell Membrane Introduction
The cell membrane is a thin barrier separating the cell from its environment, controlling what passes through.
Selectively Permeable
Selectively Permeable
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Cell Membrane Thickness
Cell Membrane Thickness
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Phospholipid bilayer
Phospholipid bilayer
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Amphipathic molecule
Amphipathic molecule
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Hydrophilic heads
Hydrophilic heads
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Hydrophobic tails
Hydrophobic tails
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Fluid Mosaic Model
Fluid Mosaic Model
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Selectively permeable membrane
Selectively permeable membrane
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Cholesterol in membrane
Cholesterol in membrane
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Membrane proteins
Membrane proteins
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How does cholesterol affect membrane fluidity?
How does cholesterol affect membrane fluidity?
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Integral proteins
Integral proteins
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Peripheral proteins
Peripheral proteins
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Membrane's structural components
Membrane's structural components
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Membrane fluidity
Membrane fluidity
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Integral protein structure
Integral protein structure
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Peripheral protein location
Peripheral protein location
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Study Notes
Plasma Membrane
- The plasma membrane separates the living cell from its nonliving surroundings.
- It is a thin barrier, 8 nm thick, controlling traffic into and out of the cell.
- Like other membranes, the plasma membrane is selectively permeable, allowing some substances to cross more easily than others.
- All cells have a cell membrane.
Cell Membrane Functions
- Controls what enters and exits the cell to maintain internal balance, called homeostasis.
- Provides protection and support for the cell.
Membrane Structure
- Lipids and proteins are major components, with carbohydrates also playing a role.
- Phospholipids are the most abundant lipids in most membranes.
- Phospholipids and most membrane proteins are amphipathic molecules.
- A membrane is a fluid mosaic of lipids, proteins, and carbohydrate.
- The membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.
- The cell membrane only lets certain substances in and out of the cell.
Phospholipid Bilayer
- Polar heads are hydrophilic ("water-loving").
- Tails (fatty acids) are hydrophobic ("water-fearing") and face inward.
Cholesterol
- Found in plasma membranes of eukaryotes.
- Modulates membrane fluidity by making the membrane:
- Less fluid at warm temperatures (e.g., 37°C) by restraining phospholipid movement.
- More fluid at lower (cool) temperatures by preventing close packing of phospholipids.
- Cells may alter membrane lipid concentration in response to changes in temperature.
Membrane Proteins
- Integral proteins span both layers of the phospholipid bilayer.
- Peripheral proteins are on either the top or bottom half of the phospholipid bilayer.
- Proteins determine most of the membrane's specific functions.
- There are two populations of membrane proteins. Peripheral proteins are not embedded in the lipid bilayer. Instead, they are loosely bounded to the surface of the protein, often connected to the other population of membrane proteins.
Membrane Carbohydrates
- Important for cell-cell recognition.
- The ability of a cell to distinguish one type of neighboring cell from another.
- Crucial for organism function.
- The basis for sorting cells into tissues and organs in an animal embryo.
- The basis for rejection of foreign cells by the immune system, and many other processes.
- Usually branched oligosaccharides (<15 monomers).
- Some are covalently bonded to lipids, forming glycolipids.
- Most are covalently bonded to proteins, forming glycoproteins.
Membrane Functions
- Receives signals from outside the cell for internal cellular activities.
- Imports and exports molecules.
- Movement of the cell.
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Description
This quiz explores the plasma membrane's role in cellular structure and function. It covers the characteristics of the cell membrane, its selective permeability, and the components that make up this vital barrier. Test your understanding of how membranes maintain homeostasis and support cellular activities.
