Exam 4: The Structure and Function of the Plasma Membrane

What kind of membrane protein penetrates into the hydrophobic part of the lipid bilayer?

What disease is caused by the disruption of the structure depicted in the figure below?

The CF mutation is present at very high levels within the Caucasian population and is thought to have arisen more than 50,000 years ago to reach its present level.Since an individual homozygous for the recessive mutant allele has such poor health,what could explain this allele rising to such a high level in the population?

You treat some cells with a proteolytic enzyme that is too large to penetrate the cell membrane (Set 1).Another group of cells is made permeable before treatment with the enzyme (Set 2).A third set of cells was not treated with the enzyme at all (controls).Proteins are then extracted from the three different sets of cells and applied to an SDS-PAGE gel.Protein W migrates to the same distance on a gel of proteins from Set 1 and Set 2; Protein W migrates a shorter distance on gels of proteins extracted from the control group than on gels of proteins extracted from Set 1 and Set 2 treated cells.Protein X migrates to the same distance on a gel of proteins from control cells and the gels of the proteins from Set 1 and Set 2.Protein Y migrates a longer distance when extracted from Set 1 cells than does protein Y in the controls; Protein Y moves an even larger distance in the gel of the extracts from Set 2.Protein Z migrates the same distance on gels of proteins from the controls and the proteins extracted from Set 1,but it migrates a longer distance in extracts from Set 2 cells.Which protein is exposed only on the exterior of the cell?

What kind of membrane protein is found entirely outside the bilayer on either the extracellular or cytoplasmic surface? These proteins are covalently linked to a membrane lipid situated within the bilayer.

Impulse propagation by a myelinated axon is called ________ conduction.

The movement of water through a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration is called ________.

A channel that opens in response to changes in ionic charge across a membrane is called a ________.

In the middle of the winter,the membranes from a tissue sample from an organism dwelling in a pond are analyzed for their phospholipid content.In the middle of the summer,another tissue sample is taken from the same type of organism and the membrane lipid content determined.The lipid content has changed.How has it changed and why?

Which protein in the red blood cell membrane appears to be responsible for the exchange of bicarbonate ions and chloride ions across the red blood cell membrane?

You are investigating the transition temperature of a membrane,the origin of which you do not know.The temperature of transition for this membrane is very sharp,occurring over an extremely narrow range of temperatures.What can you say about the composition of the membrane?

The rate of nerve impulse conduction in two different nerve cell axons differs.The first cell exhibits a rate of conduction substantially higher (about 20 times faster)than the second cell.Both cells have axons of the same diameter.What is a possible explanation for the difference in nerve conduction rate?

What amino acid is made to replace another amino acid in membrane-spanning $\alpha$ -helices by site-directed mutagenesis of the gene coding for the protein? This is done in order to determine how close together two such $\alpha$ -helices are in the structure of an integral protein.The amino acid is added to facilitate the formation of crosslinks between $\alpha$ -helices that are in close proximity.

Which disease below is caused by the deterioration of the myelin sheath?