Questions and Answers
What does the plasma membrane do?
The plasma membrane is selectively permeable.
True
What is the composition of the phospholipid bilayer?
Phospholipid molecules with polar heads facing outwards and nonpolar tails facing inwards.
What is the role of transport proteins in the plasma membrane?
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What does amphipathic mean?
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What is a bilayer?
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How does a cell's plasma membrane function?
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What are the roles of proteins in the plasma membrane?
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What are the roles of carbohydrates in the plasma membrane?
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What role does cholesterol play in the plasma membrane?
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What repels water and is positioned among the phospholipids?
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What is attracted to water?
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How many tails does each phospholipid have?
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What does a phospholipid bilayer look like?
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What model describes the plasma membrane?
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How many layers does the plasma membrane consist of?
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What are the two components that help the function of the plasma membrane?
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Identify the molecules in the plasma membrane that provide basic structure and fluidity.
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Study Notes
Plasma Membrane Overview
- The plasma membrane serves as a protective barrier for the cell, regulating interaction with its environment.
- Composed of a phospholipid bilayer, it allows the passage of nutrients into the cell while facilitating waste removal.
Key Characteristics
- Selectively Permeable: The membrane allows certain substances to cross while blocking others, maintaining internal balance.
- Phospholipid Bilayer: Features two layers of phospholipid molecules, with hydrophilic heads facing outward and hydrophobic tails directed inward.
Membrane Proteins
- Transport Proteins: Facilitate movement of substances and waste across the membrane.
- Structural Proteins: Anchor the membrane to the cell's internal framework, maintaining its shape.
- Receptor Proteins: Located on the outer surface; they transmit signals and facilitate communication with the environment.
Role of Carbohydrates
- Carbohydrates attached to proteins help define cell identity and respond to chemical signals, enabling cellular communication.
Cholesterol Functions
- Maintains membrane fluidity by preventing the fatty-acid tails of phospholipids from adhering to one another.
- A balanced cholesterol intake is important for optimal cell function.
Phospholipid Structure
- Each phospholipid molecule consists of two tails.
- The polar head is hydrophilic (water-attracting), while the nonpolar tail is hydrophobic (water-repelling).
Membrane Fluidity
- The Fluid Mosaic Model describes the dynamic nature of the plasma membrane, with various components, including proteins and cholesterol, constantly in motion.
Key Membrane Components
- Transport Proteins: Essential for the transport of substances.
- Cholesterol: Contributes to membrane stability and fluidity.
- Carbohydrates: Play a critical role in cell recognition and signaling.
Visualization of the Membrane
- The phospholipid bilayer resembles a sandwich, with polar heads facing the exterior and tails clustered inward, ensuring structural integrity and functionality.
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Description
Test your knowledge on the plasma membrane with these flashcards. Learn key terms such as selectively permeable and understand the essential functions that the plasma membrane performs for the cell. Perfect for biology students wanting to reinforce their understanding of cell structure.
