30 Questions
Which type of membrane protein serves as a structural link between the cytoskeleton and the extracellular matrix or an adjacent cell?
Transmembrane proteins
What is the estimated percentage of membrane proteins in an animal's genome?
30%
What provides the basic structure for all cell membranes?
Lipid bilayer
What is the most abundant type of membrane lipid?
Phosphoglycerides
What is the main phospholipid in most animal cell membranes?
Phosphatidylcholine
What is the major class of phospholipids built from sphingosine instead of glycerol?
Sphingolipids
What is the role of cholesterol in eukaryotic plasma membranes?
Regulates fluidity
Where are glycolipids primarily found in eukaryotic plasma membranes?
Outer monolayer
What is the main function of transmembrane proteins?
Transport molecules
What percentage of the mass of most animal cell membranes is constituted by lipid molecules?
50%
Which of the following is true about cell membranes?
They are composed of lipid and protein molecules
What is the main function of the plasma membrane?
To enclose the cell
Which organelles in eukaryotic cells have membranes?
Nucleus, endoplasmic reticulum, Golgi apparatus, and mitochondria
What can ion gradients across membranes be used for?
To synthesize ATP, transport solutes, and produce electrical signals
What do protein sensors in the plasma membrane do?
Transfer information across the membrane
How are the lipid molecules arranged in the cell membrane?
As a continuous double layer
What is the function of the lipid bilayer in the cell membrane?
To provide the basic fluid structure of the membrane
What is the thickness of the lipid bilayer in the cell membrane?
About 5 nm
What holds the lipid and protein molecules together in the cell membrane?
Noncovalent interactions
What is the role of cell membranes in the life of the cell?
They are crucial
Which type of bilayer can phospholipid molecules form depending on their shape?
Both spherical micelles and planar bilayers
What is the function of lipid asymmetry in the lipid bilayer?
To convert extracellular signals into intracellular ones
Which protein binds to the cytosolic face of the plasma membrane and requires phosphatidylserine for its activity?
Protein kinase C (PKC)
What is the translocation of phosphatidylserine in apoptotic cells thought to occur by?
Both inactivation of the phospholipid translocator and activation of a scramblase
How do phospholipid molecules arrange themselves in a bilayer?
With hydrophobic tails in the interior and hydrophilic heads exposed to water
What is the amphiphilic nature of phospholipid molecules?
Their ability to have both hydrophobic tails and hydrophilic heads
What did researchers first recognize about individual lipid molecules in the plane of a lipid bilayer?
They are able to diffuse freely
What are synthetic lipid bilayers often made in the form of?
Liposomes
What binds to specific lipid head groups found in the cytosolic monolayer of the lipid bilayer?
Cytosolic proteins
What is the enzyme protein kinase C (PKC) activated in response to?
Various extracellular signals
Test your knowledge about cell membranes and their crucial role in the life of a cell with this informative quiz. Learn about their structure, composition, and functions.
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