20 Questions
Why does a membrane containing unsaturated phospholipids stay fluid at lower temperatures?
The bent structure of the unsaturated fatty acid tails prevents tight packing.
How do fish adapt to cold environments with respect to their membrane fluidity?
By adjusting the proportion of unsaturated fatty acids in their membranes.
What role does cholesterol play in maintaining membrane fluidity?
Cholesterol expands the range of temperatures for optimal membrane function.
What observation led Larry Frye and Michael Edidin to conclude that membrane proteins move sideways within the plasma membrane?
The fusion of mouse and human cells.
What effect does a decrease in temperature have on a membrane rich in saturated fatty acids?
It increases fluidity by promoting tighter phospholipid packing.
What is the main function of the plasma membrane?
Maintaining an appropriate amount of molecules within the cell
According to the fluid mosaic model, what surrounds the cell?
Proteins and lipids
Why is the plasma membrane described as a fluid mosaic model?
Since it allows free lateral movement of proteins and other substances
What feature do phospholipids in the plasma membrane have?
Two fatty acids attached to glycerol and a phosphate group
How does the plasma membrane act as a selective barrier?
Regulating the flow of materials in and out of the cell
Which of the following statements best describes the role of the plasma membrane?
It is a selective barrier that regulates the flow of materials into and out of the cell.
What is the main structural component described in the fluid mosaic model of the plasma membrane?
Phospholipids
How do proteins contribute to the fluidity of the plasma membrane according to the fluid mosaic model?
By being embedded in the lipid bilayer and allowing lateral movement.
What is the significance of the phosphate group in a phospholipid molecule that makes up the plasma membrane?
It contributes to the fluidity of the membrane.
Why is it important for the plasma membrane to be described as a semipermeable membrane?
To highlight its role in allowing selective passage of materials.
What is the significance of the fatty acid tails of phospholipids in determining membrane fluidity?
Saturated fatty acids make the membrane dense and rigid at cooler temperatures.
How does the presence of unsaturated fatty acids impact membrane fluidity at lower temperatures?
It prevents tight packing, maintaining fluidity when saturated fatty acids would solidify.
What role does cholesterol play in maintaining membrane fluidity?
Cholesterol expands the range of temperatures for optimal membrane function.
How do organisms like fish adapt to cold environments by changing their membrane composition?
By adjusting the ratio of saturated to unsaturated fatty acids.
What experimental evidence supports the lateral movement of membrane proteins within the plasma membrane?
Fusing cells with labeled proteins demonstrated sideways movement.
Test your knowledge on the thin biological membrane found in all cells that regulates the flow of materials in and out, maintaining cell equilibrium. Learn about phospholipids and the role of the plasma membrane as a semipermeable barrier.
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