18 Questions
What is the primary reason for phospholipids to spontaneously self-associate into a bilayer in an aqueous environment?
To minimize interactions with water
Which technique is commonly used to manipulate cell membranes without causing damage?
Laser tweezers
What is a primary function of liposomes, as mentioned in the text?
Drug delivery into cells
What type of movement do phospholipids within each leaflet of a membrane primarily exhibit?
Lateral movement
Which property of cell membranes is carefully regulated and important for their function?
Fluidity
In the context of membrane proteins, what is a common property that researchers study using liposomes?
Membrane protein properties
How does the addition of cholesterol affect the fluidity of animal cell membranes?
Decreases fluidity by stiffening the membrane
Which factor would increase membrane fluidity at lower temperatures?
Longer hydrocarbon tails in phospholipids
How do cis-double bonds in phospholipids affect membrane fluidity?
Increase fluidity by reducing tight packing
What is the main role of cholesterol in cell membranes?
Stiffens the membrane and decreases permeability to water
How does temperature impact membrane fluidity?
Lower temperatures decrease fluidity
In what way does phospholipid tail length influence membrane fluidity?
Shorter tails decrease fluidity at lower temperatures
Why do enzymes in the ER membrane flip lipids from one leaflet to the other?
To maintain the asymmetry of the lipid bilayer
What is the role of Scramblase (phospholipid translocator) in the lipid bilayer dynamics?
To catalyze the rapid flip-flop of phospholipids between leaflets
What contributes to the asymmetry of the lipid bilayer?
Glycoproteins retaining orientation
How are newly synthesized phospholipids initially added to the ER membrane?
Cytosolic side of the ER membrane
What is the main function of transporters that transfer phospholipids between lipid bilayer leaflets?
Ensure proper distribution of phospholipids
How do membranes retain their orientation during transfer between cell compartments?
Glycoproteins maintain their position
Test your knowledge on membrane proteins related to transport, enzyme activity, and signaling, as well as factors affecting membrane fluidity. This quiz covers topics such as phospholipid movement within the lipid bilayer, the impact of temperature and composition on membrane fluidity.
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