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Questions and Answers
What distinguishes the plasma membrane from the internal membranes in a cell?
Which type of proteins use ATP energy to move molecules against their concentration gradient?
What do ligand-gated channels respond to?
How do carrier proteins function in moving molecules across the membrane?
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What do all membranes have in common regarding their composition?
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What factor directly impacts the fluidity of a membrane?
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Which type of transport refers specifically to the movement of water across a semi-permeable membrane?
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What type of solute concentration gradient leads to water moving out of a cell in a hypertonic solution?
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Which lipid component is enriched in rafts within a membrane?
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What type of transport does not require ATP?
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What role does cholesterol play in membrane fluidity?
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What is the main reason behind alterations in protein shape due to a single amino acid change?
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Which type of proteins make up 20-30% of all encoded proteins and have both hydrophobic and hydrophilic regions?
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Which lipid type is characterized by a glycerol backbone and a phosphate group, essential for membrane structure?
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What is the function of glycolipids, particularly prominent in the nervous system?
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Which type of biological molecules contain longer, highly saturated fatty acyl chains and are less common in cell membranes?
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What affects the fluidity of a biological membrane by interacting with both hydrophilic and hydrophobic regions?
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Study Notes
Cell Membranes
- The plasma membrane is distinct from internal membranes in a cell due to its selective permeability and ability to regulate the exchange of materials with the external environment.
Transport Mechanisms
- Carrier proteins use ATP energy to move molecules against their concentration gradient, a process known as active transport.
- Ligand-gated channels respond to specific molecules (ligands) to facilitate transport across the membrane.
Membrane Composition
- All biological membranes have a common composition featuring a phospholipid bilayer with hydrophilic heads and hydrophobic tails.
- The fluidity of a membrane is directly impacted by temperature, with increased temperature leading to increased fluidity.
Osmosis and Solutes
- Osmosis refers specifically to the movement of water across a semi-permeable membrane.
- A hypertonic solution has a higher solute concentration, leading to water moving out of a cell.
Lipid Components and Rafts
- Cholesterol is enriched in rafts within a membrane, contributing to membrane fluidity and structure.
- Cholesterol helps maintain membrane fluidity by interacting with both hydrophilic and hydrophobic regions.
Protein Structure and Function
- A single amino acid change can alter protein shape due to changes in hydrophobic and hydrophilic interactions.
- Integral proteins (20-30% of encoded proteins) have both hydrophobic and hydrophilic regions, allowing them to span the membrane.
Lipid Types and Functions
- Phospholipids, characterized by a glycerol backbone and phosphate group, are essential for membrane structure.
- Glycolipids, prominent in the nervous system, function as cell surface receptors and in cell-cell interactions.
- Sphingolipids, less common in cell membranes, contain longer, highly saturated fatty acyl chains.
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Description
Test your knowledge on the composition and fluidity of cell membranes, including the impact of different lipid types, saturation, fatty acid length, and cholesterol presence. Explore concepts like lipid rafts, cholesterol influence, protein movement within membranes, and signaling roles.
