Exam 4: The Structure and Function of the Plasma Membrane

Why would the transmembrane portion of membrane proteins shown in the figure below be unlikely to be composed of an $\alpha$ -helix made of hydrophilic amino acids?

When membrane lipids are extracted from cells and used to prepare artificial lipid bilayers,cholesterol and sphingolipids tend to self-assemble into ________ that are more gelated and highly ordered than surrounding regions consisting primarily of _________.

How do Na+ ions enter a neuron when an action potential is initiated?

What technique allows an investigation of the microheterogeneity of a membrane so that one can see localized differences in different parts of the membrane?

What is thought to cause the sodium channels that initiate an action potential to be inactivated for a brief time after being open for about 1 msec?

What are some possible explanations for the tendency of CF patients to develop chronic lung infections?

You have fused a mouse cell and a human cell and then treated the cell with specific antibodies that are covalently linked to fluorescent dyes (antibodies to mouse proteins - green; antibodies to human proteins - red).What does the cell look like immediately after fusion?

What evidence convinced Overton that membranes were composed of lipids?

A membrane's transition temperature is determined and found to stretch over a wide range of temperatures.The membrane also exhibits high stability and a reduced permeability similar to that in most mammals.What membrane component is responsible for these traits and how does it do it?

Where in a myelinated axon are nearly all of the ion channels concentrated?

______ trigger fusion of synaptic vesicles with the synaptic membranes of the presynaptic cell.This same stimulus also triggers ________.

What did Davson and Danielli add to their model of enzyme structure to explain the passage of polar solutes and ions through the membrane and to account for their selective permeability?

Which part of a neuron conducts impulses away from the cell body toward the target cell(s)?

What property of membranes allows interactions to take place within the membrane,including the assembly of membrane protein clusters at particular sites and the formation of specialized structures?

Diffusion during which the substance to be transported binds selectively to a membrane-spanning protein,which helps the process along,is called ________.

What happens after a subthreshold depolarization?

If Gorter and Grendel,as described in the figure below,extracted lipids from the membranes of red blood cells and determined that they covered 96 mm² of water,what would you estimate as the surface area of the red blood cells from which the lipids were extracted?

What technique can clarify the dynamic events that occur as a protein functions by introducing into the protein chemical groups (called nitroxides)that contain an unpaired electron? The properties of these nitroxides are sensitive to the distance that separates them and the unpaired electron produces a characteristic spectrum that can be monitored by the technique in question.The technique yields information about the distance between selected protein residues.

Which protein in the Question above is likely to be buried within the membrane?

_________ can be used to trap integral proteins and drag them through the membrane with a known force,using forces generated by a focused laser beam.This yields information about the presence of membrane barriers.