Exam 4: The Structure and Function of the Plasma Membrane

In the Na+/glucose cotransporter,_____ moving down its gradient drives the transport of _____ against its gradient.

A molecule normally enters a cell by simple diffusion through the lipid bilayer.What happens if you artificially reverse the molecule's concentration gradient?

You are exploring a rather inhospitable planet,which has seas that are somewhat hydrophobic in nature.Surprisingly,there are living organisms in the seas whose cytoplasm is hydrophobic to a similar degree.These organisms have membranes made primarily of phospholipids arranged in a bilayer.What is the most probable orientation of these phospholipids?

What enzyme was instrumental in the discovery of GPI-anchored proteins? It was found that this enzyme would release certain membrane proteins from a membrane.

What directly or indirectly determines the transition temperature?

In the figure below,why is the stealth liposome coated with polyethylene glycol? What directs the stealth liposome to its target body tissue? Where are lipid-soluble drugs and water-soluble drugs found in stealth liposomes?

A process in liver cells stops when they are exposed to the inhibitor ouabain,which is an inhibitor of the Na+-K+ pump.What do you conclude about the liver cell process?

Why did liposomes not work against diseases as hoped when they were first tried?

Which of the following is not a function of membranes?

Which protein(s)below is(are)thought to be involved in and influence the stability of red blood cell membranes and the cells themselves by imparting strength,elasticity,and pliability to the membrane?

The majority of alleles responsible for CF in the United States contain the same genetic alteration,designated DF508.What is the significance of this alteration and how does it lead to CF?

If you were able to study nerve conduction in vitro and you added ouabain,an inhibitor of the Na+-K+ ATPase,to the system,would you expect to see the conduction of nerve impulses cease immediately?

Where is the neuron cell nucleus located?

What is the distinguishing characteristic of a P-type pump?

Gorter and Grendel extracted lipids from human red blood cells.They calculated the total surface area for these red blood cells and found it to be 36 µ2.How much surface area would these lipids cover once they were spread across the surface of water?

You are studying a transport molecule.It appears to bind temporarily to the molecule to be transported.During normal transport,no energy is expended.The addition of a particular molecule that closely resembles the normally transported molecule inhibits transport.An increase in the concentration of the normally transported molecule in the presence of a constant concentration of the inhibitor increases the rate of transport.What kind of transport is described and what is the inhibiting molecule?

You are characterizing an isolated membrane protein.The protein is exposed on both sides of the membrane.Over much of the central part of its surface,there are hydrophobic amino acids,while the ends are hydrophilic.It crosses the membrane a number of times.There is an opening in the center of this protein lined by hydrophilic amino acids.What kind of protein is this and what is its probable function?

They are more gelated and highly ordered than the surrounding more fluid and disordered regions in artificial membranes that consist primarily of phosphoglycerides.They contain higher concentrations of sphingolipids and cholesterol and certain proteins become concentrated within them.What are they?

Once the structure of one member of a membrane protein family has been determined,researchers can usually apply a strategy called __________ to learn about the structure and activity of other members of the family.For example,solution of the structure of the bacterial potassium channel KcsA provided a lot of data that could be applied to the structure and mechanism of action of the much more complex eukaryotic potassium channels.

A transport system that moves one solute into the cell and another one out of the cell during a single cycle accompanied by the expenditure of energy through ATP hydrolysis could be called a(n)_______