23 Questions
What is the main function of aquaporin?
Channel that mainly transports water
Which type of proteins contain membrane-spanning hydrophobic alpha helices and hydrophilic domains extending from the cytosolic and exoplasmic faces of the membrane?
Integral membrane/transmembrane proteins
Where is porin found as an example of integral proteins?
In the outer membrane of bacteria like E.coli
What is the structure of aquaporin like?
Closed barrel mainly containing beta sheets
Which membrane protein function involves joining cells together?
Intercellular joining
What is a common feature of integral proteins' membrane-spanning domain?
Hydrophilic amino acids forming alpha helices
How do cholesterol molecules enhance the permeability barrier properties of the lipid bilayer?
By orienting themselves with their hydroxyl groups close to the polar head groups
What is the role of glycolipids in cell recognition processes?
Acting as binding sites for lectins
How does cholesterol affect the fluidity of the lipid bilayer?
By making the layer less fluid
What is the positioning of cholesterol molecules in the lipid bilayer?
Close to the sugar groups of glycolipids
What does cholesterol prevent by making the lipid bilayer less fluid?
Preventing hydrocarbon chains from coming together and crystallizing
What is the main function of membrane lipids according to the text?
Allows cells to interact with the watery environment while remaining water-resistant
Which type of fatty acids are found in phospholipids according to the text?
Both saturated and unsaturated fatty acids
What is the role of phosphatidylcholines (PC) in cellular membranes?
Constitute the most abundant phospholipids in plasma membranes
What is the significance of asymmetry in the lipid bilayer according to the text?
Regulates programmed cell death (apoptosis)
Where are phosphatidylethanolamine and phosphatidylserine predominantly located within the membrane according to the text?
Inner monolayer
What is the main characteristic of sphingolipids according to the text?
Contain a long hydrocarbon chain
Which type of proteins are usually bound to the membrane indirectly by interactions with integral membrane proteins or directly by interactions with lipid head groups?
Peripheral proteins
What type of group is attached to the N-terminal glycine residue in acylation?
Fatty acyl group
Which protein can transform cells only when it has a myristylated N-terminus?
v-Src
In prenylation, what type of group is attached to a cysteine residue near the C-terminus?
Unsaturated fatty acyl group
What is the general term used for the Carbohydrate layer on the membrane described in the text?
Glycosylphosphatidylinositol (GPI)
Which type of proteins are associated with integral proteins or membrane lipids by specific noncovalent interactions?
Peripheral proteins
Test your knowledge on the structure and function of cell membranes, including how they maintain differences between organelles and cytosol, regulate molecule transport, and interact with the watery environment while remaining water resistant. Explore the significance of the lipid bilayer in cell signalling, impermeable barrier formation, stability, and cell adhesion.
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