Biological Membranes and Transport

What are the typical thickness and appearance of biological membranes when viewed in cross-section with an electron microscope?

According to the fluid mosaic model, what is the primary reason for the fluidity of the membrane?

In the human myelin sheath, what are the approximate percentages by weight of protein, phospholipid, and sterol?

Which type of lipid aggregate is favored in water when the cross-sectional area of the head group is greater than that of the acyl side chain, as seen in free fatty acids or detergents like SDS?

What is the approximate thickness of a lipid bilayer?

In the plasma membrane of a human erythrocyte, which lipids are predominantly found in the outer (exoplasmic) leaflet?

How are integral membrane proteins primarily anchored to the lipid bilayer?

What is the orientation of the glycoprotein glycophorin in the erythrocyte membrane?

What is the approximate number of amino acid residues required for an alpha-helical segment to span the 30 Å thickness of a lipid bilayer?

Which two amino acid residues are frequently found at the interface between the lipid and water phases of a membrane, where they are thought to act as interface anchors?

The 'positive-inside rule' for membrane proteins states that which three positively charged amino acid residues are found more commonly on the cytoplasmic face of membranes?

In the liquid-ordered (Lo) state of a lipid bilayer, what is the characteristic arrangement of the acyl chains?

What is the term for the movement of a lipid molecule from one leaflet of the bilayer to the other, a process that is generally very slow without enzymatic catalysis?

Which type of protein catalyzes the ATP-dependent movement of aminophospholipids like phosphatidylethanolamine and phosphatidylserine from the extracellular to the cytosolic leaflet of the plasma membrane?

The FRAP (fluorescence recovery after photobleaching) technique is used to measure what property of membrane components?

Membrane rafts are microdomains in the plasma membrane that are enriched in which two specific types of molecules?

Caveolin, an integral membrane protein that induces the formation of caveolae, is anchored to the membrane in part by what type of covalent modification?

A superfamily of proteins containing BAR domains is involved in what key cellular process related to membranes?

The proteins v-SNARE and t-SNARE are essential for initiating what cellular process?

What is the typical energy barrier that a polar solute must overcome to pass through a pure lipid bilayer via simple diffusion?