Cell Membrane Structure and Lipid Bilayer Function Quiz

What is the main function of aquaporin?

Cell signaling
Channel that mainly transports water (correct)
Attachment to cytoskeleton
Cytoskeleton classification

Which type of proteins contain membrane-spanning hydrophobic alpha helices and hydrophilic domains extending from the cytosolic and exoplasmic faces of the membrane?

Fibers of extracellular matrix
Integral membrane/transmembrane proteins (correct)
Membrane protein functions
Extracellular matrix proteins

Where is porin found as an example of integral proteins?

In the cytoplasm
In the extracellular matrix
In the outer membrane of bacteria like E.coli (correct)
In the fibers of the extracellular matrix

What is the structure of aquaporin like?

Closed barrel mainly containing beta sheets (C) Signup and view all the answers

Which membrane protein function involves joining cells together?

Intercellular joining (A) Signup and view all the answers

What is a common feature of integral proteins' membrane-spanning domain?

Hydrophilic amino acids forming alpha helices (D) Signup and view all the answers

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 (D) Signup and view all the answers

What is the role of glycolipids in cell recognition processes?

Acting as binding sites for lectins (B) Signup and view all the answers

How does cholesterol affect the fluidity of the lipid bilayer?

By making the layer less fluid (B) Signup and view all the answers

What is the positioning of cholesterol molecules in the lipid bilayer?

Close to the sugar groups of glycolipids (D) Signup and view all the answers

What does cholesterol prevent by making the lipid bilayer less fluid?

Preventing hydrocarbon chains from coming together and crystallizing (D) Signup and view all the answers

What is the main function of membrane lipids according to the text?

Allows cells to interact with the watery environment while remaining water-resistant (B) Signup and view all the answers

Which type of fatty acids are found in phospholipids according to the text?

Both saturated and unsaturated fatty acids (A) Signup and view all the answers

What is the role of phosphatidylcholines (PC) in cellular membranes?

Constitute the most abundant phospholipids in plasma membranes (C) Signup and view all the answers

What is the significance of asymmetry in the lipid bilayer according to the text?

Regulates programmed cell death (apoptosis) (B) Signup and view all the answers

Where are phosphatidylethanolamine and phosphatidylserine predominantly located within the membrane according to the text?

Inner monolayer (C) Signup and view all the answers

What is the main characteristic of sphingolipids according to the text?

Contain a long hydrocarbon chain (B) Signup and view all the answers

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 (B) Signup and view all the answers

What type of group is attached to the N-terminal glycine residue in acylation?

Fatty acyl group (B) Signup and view all the answers

Which protein can transform cells only when it has a myristylated N-terminus?

v-Src (D) Signup and view all the answers

In prenylation, what type of group is attached to a cysteine residue near the C-terminus?

Unsaturated fatty acyl group (C) Signup and view all the answers

What is the general term used for the Carbohydrate layer on the membrane described in the text?

Glycosylphosphatidylinositol (GPI) (C) Signup and view all the answers

Which type of proteins are associated with integral proteins or membrane lipids by specific noncovalent interactions?